Optimum diet
This article by Dr Piotr Wozniak is part of SuperMemo Guru series on memory, learning, creativity, and problem solving.
Summer 2020 (see: Feedback)
Designing optimum diet
The secret to optimum nutrition is hiding in the brain. It is less about what we eat, or how much we eat. It is far more about how the brain can effectively employ its control systems to achieve its nutritional goals.
Scientists, businesspeople, amateurs, and charlatans designed thousands of diets in hope of staying slim, fit, and healthy. Some tinker with diets to get rich on other people's hopes. Most of those diets bring more harm than benefit. The harm often does not come from the diet itself, but from its inept application. Moreover, dieters often go on a whole string of different diets with different effects without trying to understand their implications. Others return to a diet that works but enter yo-yo oscillations that are often as harmful as obesity itself.
Here I would like to use my best knowledge of the brain and human physiology to deduce the optimum "design" of the diet for humans. To be precise, we can only figure out some central principles. Human variability, different health status, and our continual abysmal ignorance of human metabolism and physiology leaves us with little choice but to just grope in darkness with very general guidelines. I spent decades studying genes, hormones, metabolic pathways, etc. The incessant inflow of new research, and the complex interaction of the ingredients of the metabolic machinery makes it necessary to resort to the only true authority on optimum feeding: brain's own control systems.
The central premise of this texts is that obesity epidemic is not an effect of abundance, laziness, junk food, or poor self-control. Obesity is rooted in the injury to the control systems involved in optimization of nutritional intake. That injury inflicted by the modern lifestyle is preventable and, to a degree, reversible.
Principles of optimum diet
Healthy eating is extremely easy. If we look at an average child in a reasonably natural environment, his diet is likely to lead to excellent health, fitness, and well-being. This is the first essential hint. We are all born with all crucial control systems needed for healthy eating. A good place to study natural eating habits is hunter-gatherer tribes that still inhabit this planet. The first principle of healthy eating is to employ natural healthy appetite control systems.
We ruin those youthful control systems by incessant intervention. First we intervene in our lives with authoritarian parenting, "modern" parenting inventions, stressful lifestyles of the parent, complex family relationships, daycare, kindergarten, early academic education, school, etc. By the age of 10, in terms of control systems, most of kids are damaged goods. Their ability to control their appetite for healthy eating is largely lost. An average 10 years old will often be conditioned to love chips, chocolate, and/or coke. He may be conditioned to use food as comfort, and to eat more than necessary. Stress of schooling or authoritarian parenting will lead to reward deprivation, which is the first step towards unhealthy addictions, incl. food addictions. The best indicator of being in the safe zone is the pleasure of living. The second principle of healthy eating would then be to live a simple, happy, natural life in harmony with one's biological and psychological needs (see: Farmer's lifestyle).
An important clue comes from centenarians. They live a life of routine. Their entire life is a continual incremental experiment on well-being. Centenarians know what's good for them and they adapt accordingly. That "good thing" may be a cigar or a shot of vodka. As long as they stick to their routine, they are in a safe zone. They give their brains and their physiology enough time to adapt to adverse stimuli they meet on their way every single day. This is why they are centenarians. It is the centenarian who is likely to retain and continue his good eating habit till her last day. The next principle of my perfect diet is then a repetitive routine that allows of incremental progress and adaptation by sensing or observing the effects of change to the routine. In repetitive life, small change may have easily observable consequences. Most of all, the brain can employ its neural learning strategies to look for patterns and adapt accordingly. The third principle is to live a simple life based on an observable routine.
Nutritionists count calories, optimize the content of the meals, prescribe exercise, etc. However, the brain responds to all those inputs by running its own adaptation routine that is aimed at satisfying nutritional needs and maximizing the perception of well-being. The exact optimization criteria and their evolution in the process of network conceptualization are unknown (see: Brain's development optimization criteria). However, if the diet stands in disagreement with the criteria established by the brain, it will either fail, or the control systems may suffer injury (see: War of the networks). Any diet that quarrels with the brain plan will do some kind of damage. The type and degree of damage is hard to predict.
The principles of the optimum diet must ensure that (1) the brain control systems remain healthy and (2) the data input to the brain does not go beyond manageable complexity.
Weight gain hypothesis
We do not gain weight because we just eat too much. The weight is controlled by the appestat, which generates appetite for specific foods that meet specific nutritional needs. A healthy control system would make sure that we be unable to eat more than we can process. In healthy appetite control, you will eat as much as necessary and push off excess meals as unpalatable or even repulsive.
We deposit fat only (1) if the body wants to deposit fat, (2) if the brain control systems are injured, (3) if control systems are overwhelmed, (4) if control systems are not ready, or (5) if control errors lead to wrong physiological responses. We deposit certain optimum amount of fat in development due to the physiological function of fat. If the brain control systems get injured (e.g. in yo-yo dieting), the appestat will malfunction and may ask for more food intake or more fat deposits than the optimum that maximizes overall well-being in the long run. Control systems may get overwhelmed if complexity of data on input exceeds network's adaptation capacity (e.g. fast changes in meal timing, composition, and nutritional side effects). Control systems may fail if they tackle unknown data (e.g. new artificial foods) or if physiological sensors provide no input (e.g. tasteless and odorless toxins). Finally, network errors or recognition errors are a norm in many circumstances (e.g. in sleep deprivation, fake foods, food mimicry, etc.). Network errors of sleep deprivation or chronic stress will affect multiple control systems of which nutritional control is one. Additionally, in distress, the organism may pull resources from one goal to another goal. For example, in infection, nutritional needs may change to combat the infection, and may depart from the usual optimum. Similarly, during a fight-or-flight response, the appestat will be turned off. One control system will silence another control system. In distress, we may give up feeding entirely.
The main threat to a healthy control system is reward deprivation. If the brain is deprived of natural reward, e.g. pleasure of learning, or is systematically penalized (e.g. for bad performance at school), it may use food as a form of compensation, which leads to a chain reaction of errors in adaptability that will ultimately lead to some form of injury to control systems (e.g. responsible for the pleasure of learning, or the pleasure of optimum nutrition).
The brain is a perfectly adapting device. For al the above reasons, it needs to be provided with repeatable input with decodable patterns to provide optimum responses that will maximize well-being in the long run. It is easier for the brain to adapt to optimal feeding if the exercise is always hooked to the same circadian anchor (i.e. if it occurs at the same time of the day). It is even more important to deploy a repeatable and recognizable feeding routine. Similar meals, same times, similar nutritional parameters, known, safe and natural food types, etc.
Healthy feeding requires healthy appetite control that relies on recognizable feeding input patterns.
Associative adaptation
Nutritional adaptation has probably been best studied in animal poisoning. If nausea is induced in animals that have just consumed a specific meal, aversion for that meal can be induced (for more see: "Oliver Scott Curry is wrong about associationism"). This mechanism governs all appetites and aversions in feeding. Most people love chocolate, but it is possible to generate aversion for chocolate. All we need is to eat too much. If we eat enough chocolate to produce negative side effects such as nausea, vomiting or chocolate poisoning, we may need prolonged incremental therapy to restore the ability to enjoy chocolate again. If we want children to stay away from alcohol, prohibition and threats may be a wrong way. If a child consumes enough alcohol to induce vomiting, he might be protected for many years. I like to joke that I quit smoking in the first grade of primary school. In reality, when I tried my first smoke, I did it in secret and smoked too much. I experienced a nasty case of nicotine poisoning. I never had a smoke since. I love beer, but I was able to enjoy sweet low alcohol brown beer only at the age of 32. One of the reasons was the fact that my brother gave me a gulp of beer in childhood. The bitter taste stayed with me for decades.
The mechanism for food valuation is analogous to knowledge valuation. The memory of feeding and its context pattern live in the brain as a form of a concept map activation for a longer while. All rewards and penalties that occur in the period of activation have the ability to recompute the valuations of the active concepts. If food leads to reward, the positive valuation will be subject to spreading activation that will enhance the valuation of all input patterns that lead to the rewarding event. We may subconsciously register that a green bush on the left turn on the road leads to a hot dog stand that provides rewarding food. With repeated exposure, we may condition a preference for green bushes when choosing roads in the future. The opposite happens in case of a penalty. An identical wave of activation will spread in the brain, but it will look like a photo negative. Activating inputs will be suppressed, and inhibitory inputs will be enhanced. If the same green bush leads to vomiting behind a beer stand, we may learn to hate beer and acquire some fleeting dislike to green bush patterns. For an example of similar associations produced while learning, see: How school turns off memory.
An individual subjected to strict dieting will form many bloated valuations of all factors that favor cheating the diet. The entire feeding optimization will become skewed in favor of gaining weight along a trajectory similar to the one used in dieting, in reverse. For example, if the diet was painfully restrictive in the consumption of sweets, the value of sweets for the brain may become blown out of proportion. If dieting and weight gain enter yo-yo oscillation, it may gradually become more difficult to control selective high concept valuations. For the diet to succeed, the war of the networks will take place. The problem causing valuations will be taken out of the equation. Food will become less valuable. Dieting will become less painful. The control system will stop playing its role. The individual will be left with a lifelong need to micromanage her own feeding. This phenomenon is bound to shorten a human life.
From the point of view of optimum nutrition, we need to remember that the entire mechanism of conceptual association is fraught with error. We need repeated exposure in varying contexts before we can extract the value from associations. This is why a toddler might taste all objects on its way, and a centenarian will live a routine that hones her associations to perfection. The adaptation may be optimum, but it takes time and data before it becomes effective.
An immortal myth says that common cold is caused my low temperatures. It is a case when conceptual association fails. We get infected in various contexts, and the brain may form an association with crowded spaces, stuffy rooms, or sleep deprivation that undermines immunity. However, the response to the infection leads to ramping up the thermostat. This inevitably leads to shivers that are then associated with all bad effects of the infection. Most of associative learning occurs subconsciously, but the association of shivers and the infection is so powerful that it penetrates up to the level of consciousness. We learn to believe that cold causes colds.
The fact that we may form mistaken associations is one of the factors that contribute to obesity.
Spaced repetition in nutrition
Understanding of memory in society is poor. The whole school system is designed in a way that puts emphasis on one component of memory, retrievability, and neglects the other, more important component: stability. In the process, schools induce a buildup of toxic memories. This cripples societal adaptation powers. In a similar way, the way we try to control our nutrition works in favor of obesity. The epidemic of obesity and the epidemic of the hate of learning have a lot in common. At first, we attempt to control instinctive behaviors, then we condition undesirable side effects, and then seal pathological reflexes by means of the war of the networks. Understanding of the spacing effect is central in those processes.
The brain is a perfect adapting device. It will garner data from the environment and seek optimum response to data patterns. If we receive a visual food signal (e.g. a candy on a coffee table, or a piece of meat on a frying pan), we may experience instant cravings. Those cravings do not need to be associated with the current needs of the organism. You may experience cravings even if the body is in a state of perfect nutritional satisfaction. The response to the food signal today and in the future, will determine the level of cravings. If you refuse the candy, the cravings may disappear relatively fast. If you refuse it next time you see it, your cravings may get weakened. Your optimum exposure to candy, followed by a refusal, will be governed by the rules of spaced repetition. Gradually, you will condition the mind that the candy is of no nutritional benefit. The craving may disappear entirely. Similarly, if you eat the candy, the brain will compute its nutritional benefit using its best sensors. The resulting benefit will lead to the re-evaluation the original signal. If candy is important for your health, the value of the signal will be scaled up and your cravings may increase at next exposure. Analogously, if you are fully sated, and the candy only provides extra calories that your body will somehow have to get rid of, the value of the signal will drop. With regular exposure in a similar context, the value of a signal may stabilize anywhere on the spectrum from very low to very high.
The most interesting thing happens to a dieter. If he refuses the candy, the cravings may get suppressed. However, if he ever fails to refuse, and the period of refusal is long enough, he may evoke the spacing effect. As dieters are often under a permanent caloric deficit, the value of candy may turn out huge. In such a case, the memory effect of the candy will be astronomical. The brain will learn all the context in which the candy can be consumed and maximize all behaviors that leads to the satisfaction. The dieter will remember the color of the room, the street, the face of the coffee shop owner, the words that triggered the reward, etc. Next time the dieter will see the candy, his brain may expend extra energy in trying to obtain the satisfaction. This is how obsessions are born. If the dieter is strong willed, he may go back to his disciplined approach, and control the craving. However, if he survives for months or years, the next slip may only stabilize the reflex. This is how variable reward exerts is powerful effect on addictions. This is how reward deprivation generates addicted video gamers. This is how a dieter comes to the edge of "being ready to kill" just to satisfy a craving. Addictions to food and videogames have the same underlying mechanism. They are very difficult to break due to the high level of memory stability. The best formula is to avoid a "rational override" of the control systems. If some override is necessary, e.g. to break a prior addiction (e.g. to candy), it should not be intermittent to avoid variable reward. If the override is a miscalculation, it will either generate a craving that cannot be conditioned out, or it will result in a permanent injury to the control system responsible for the particular craving.
Conceptualization of the routine
In the course of nutritional adaptation, the appetite control systems will pass all natural conceptualization stages that characterize the overall brain's development in the course of a lifetime: from the uterus to the last breath.
A perfectly adapting toddler will taste all things around and imitate parents or older sibling in their nutritional habits. A child will gradually discover her routine preferences, e.g. gaming in the morning, playing outdoors during the day, main meal upon return, videos in the evening, etc.
If a child's preferences are respected, and the lifestyle is not interfered with by school or job requirements, the teen, and later the adult will quickly settle on a routine that may change little over decades. Sadly, many people get a good chance to settle on a routine only in retirement. Those who do it early and effectively, are most likely to survive to be a centenarian. This is the reason why there are so few centenarians without a routine.
In terms the of nutritional conceptualization, plasticity is the ability to learn and adapt to nutritional environments to satisfy nutritional needs. Stability is knowledge of the optimum routine, and knowledge needed for handling routine exceptions. The graph explains why children are more chaotic than centenarians. They are at the stage of data gathering and early conceptualization:
Figure: Hypothetical course of learning and conceptualization in a fixed-size concept network. The naïve network begins the learning process at high plasticity (in red). As individual concepts form, they are consolidated and stabilized. The overall stability of the network keeps increasing (dark blue). The speed of conceptualization (in orange) is a resultant of plasticity and stability. It reaches its theoretical maximum somewhere on the way from the random graph stage to a sparse representation stage. This is the time of a large supply of concepts that may be subject to generalization, and a good balance between stabilization and forgetting. The overall problem solving capacity of the network (light blue) is negligible at first, and tends to saturate with network stabilization. Large number of well-stabilized concepts makes it harder to find new plastic network nodes for further conceptualization. The maximum capacity of the network depends on its size. Speed of learning in spaced repetition at older ages seems to indicate that the size of the concept network of the human brain is high enough to provide for lifelong learning without noticeable saturation. See: Conceptualization theory of childhood amnesia and How much knowledge can human brain hold
Pleasure of eating
Eating is pleasurable. The way the brain responds to food determines our health and our weight.
Palatability
Dr Guyenet is an obesity expert with vast knowledge of neuroscience and nutrition. He states correctly that the key to obesity hides in the brain. However, he believes that the main culprit might be hyper-palatability: western foods are engineered to be irresistible. Guyenet even proposed a cook book of bland recipes that might remedy the problem of obesity. Bland Food Cookbook was an April Fools' Day joke.
In his excellent analysis, Guyenet presented a hypothesis on hyper-palatability: "The Case for the Food Reward Hypothesis of Obesity". He then meticulously collected all the necessary evidence to prove the thesis!
With this effort, Guyenet painted the science of obesity in the most coherent, concise, and evidence-rich detail I have seen thus far. In a most comprehensive review quoted by Guyenet, researchers found what intuition tells us must be true: "All reviewed studies have shown increased intake as palatability increased" (source).
However, as I come from a field of memory and learning, I see a major flaw in the entire line of reasoning that proves the dangers of hyper-palatability. We need to begin from the question about the optimization criterion used by the brain (compare: Brain's development optimization criteria). For evolutionary reasons, the optimization must ensure the provision of nutritional needs, and little else. The provision occurs with the help of all best evidence of which taste and aroma signals are an important subset.
Palatability is only a set of cues for the brain to recognize foods that help meet nutritional needs that maximize well-being. If we remove those cues, it is a matter of time before the brain re-calibrates and re-learns the art of feeding optimally. In optimum diet, the trick is not to change how we perceive foods, but how to make sure that the set point of the appestat is unbiased. Equally well we can increase palatability, temporarily increase food intake, and let the brain adapt to the new conditions of exquisite cuisine.
In other words, instead of suffering bland diets, we can provide the same nutrition and higher reward, which requires less compensation. This is in line with my overall formula for a fulfilling life: provide healthy rewards where available. This has a protective effect against all forms of unhealthy and compensatory reward-seeking, incl. addictions.
Guyenet says that for his hypothesis to be true: "Increasing the reward/palatability value of the diet should cause fat gain in animals and humans". This is not enough. We should rather say: "Increasing the reward/palatability value of the diet should cause LONG-TERM fat gain in animals and humans". It is absolutely necessary to give the appestat a chance to re-learn the new nutritional context. The best known verification of my reasoning came from Dr Tordoff research (Monell Center, 2017). I need to stress that it is very risky to compare humans to rodents with respect to adaptability due to vastly different timelines of conceptualization and stabilization!
Tordoff himself noticed (source):
Even though we gave mice delicious diets over a prolonged period, they did not gain excess weight. People say that "if a food is good-tasting it must be bad for you", but our findings suggest this is not the case. It should be possible to create foods that are both healthy and good-tasting
Metaphorically speaking, we cannot suppress the sex drive by making one's sexual partner unattractive. The brain's natural response is to seek a new mate.
The problem with research on obesity is more general. Researchers are overly focused on how foods affect weight gain, instead of paying more attention to why we choose particular foods to eat. Provocatively, I would frame it as follows:
We do not get fat because we eat too many calories, but because we want to eat too many calories.
In simple words, when the appestat is set correctly, you can overfeed a healthy individual and he would compensate by expending more energy (within feasible limits). These are the appestat errors that make us want to eat more to satisfy falsely perceived needs. We need to target appestat errors and appestat's compensatory actions in reward deficits.
Exquisite cuisine
My personal story inspires a claim that palatability should not be an issue in weight gain.
Capsaicin is the central ingredient for the power of chilly. It directly affects sensory neurons causing pain. However, all chiliheads can testify that a well-dosed chilly brings nothing but pleasure. This can only be explained by the release of natural painkillers. Every marathoner knows the pleasure of pain. I love to come from a football match with aches and bruises. They provide a pleasurable sense of having had a good game. They also lead to a pleasure of healing. The afterglow of painful experiences is registered in the brain. If it is pleasurable, the brain will learn to associate a particular food with its reward. Healthy addiction to chilly is born. A healthy meal on fire makes one feel like a lion after a bruising fight with an antelope: the highest degree of culinary satisfaction.
Could this pleasure make one seek more food. In my case, it can easily be proven false. I do meet Guyenet's criterion. Given a choice between bland and spiced food, I would eat more of the spiced variety. However, this criterion does not hold in real life. I dose portions for my main meal deliberately. They are relatively modest. I like to compare them to Minnesota Starvation Experiment. I could even risk a claim that adding extra spices makes me feel more reassured I will not be seeking a correction after the meal. My way of "cheating" is to make the meal very tasty and very big. I drown it in a pile of veggies that might double the caloric intake. I conditioned an undying love for veggies in the same way as I conditioned a dislike for cakes (described here).
My main meal feels huge and satisfactory. Once I step off the table, food and dieting are all gone from my mind. Palatability does not increase my portions, but it definitely increases the sense of well-being. I am not a dietary role model, but I vote for exquisite cuisine. Solutions to obesity should leave palatability aloneWorking on her PhD dissertation, Sofie Lemmens found that (source):
Eating a highly liked food item induces a more distinct decrease in 'wanting' for food items in general and category-specific 'liking', than eating a sufficiently liked neutral food item
Dr Guyenet insists that "Individual sensitivity to food reward should predict future fat gain". I agree. Good sensitivity is a source of information for the appestat. It is those with weak sensitivity to food reward who may fall victim to imbalance.
Wanting and liking
When studying reward in nutritional habits, it is helpful to know the difference between wanting and liking.
In the science of pleasure, wanting and liking have been defined pretty precisely in animals (e.g. in rats feeding on sucrose). While wanting is primarily dopamine based, liking is more opioid in nature. Wanting determines motivation that initiates behaviors that lead to liking, which is the ultimate experience of the reward. For example, wanting can be expressed by circling around the kitchen table, while liking by the pleasure of consuming foods snatched from the table.
As wanting and liking often live in mutual feedback loops, they can be hard to separate. For example, an individual busy with his daily activities may suddenly be triggered into wanting by a meeting with a potential sexual mate. As of that point, a spiral of tactile, psychological or hormonal signals may begin wanting, followed by behaviors that cause liking, that intensify wanting, that spiral into the acme of liking, i.e. orgasm. After an intercourse, wanting may be suppressed by the fact that liking may be turned off or replaced with aversive reactions. The mind turns to different sources of reward (e.g. a smoke, reading a paper) or just goes to sleep.
The distinction between wanting and liking may become very important in addictive behaviors (see: Pleasure systems in the brain by Berridge and Kringelbach). For example, in drug abuse, downregulation may effectively suppress liking, while leaving behind a set of habits expressed as wanting that may become magnified by an elusive quest for liking. Wanting without liking is central to the pathology of addiction. Dopamine stimulation may lead to compulsive behaviors such as gambling, gaming, pornography, compulsive shopping, etc. Compulsive eating is also on that list.
I posit that in healthy eating, wanting must be a pure expression of nutritional needs, and liking should provide powerful reward. In modern life, we often condition wanting in irrelevant contexts (e.g. when food is used as comfort). In addition, we undermine liking by unhealthy eating habits.
In a life based on a routine, e.g. farmer's lifestyle it is possible that wanting may be routinized, and liking becomes the only dominant component of food reward. This seems to minimize wanting dissociated from nutritional needs.
For contrast, we can condition wanting in situation when food becomes substitute reward in conditions of distress. By using food as comfort, we risk a form of desensitization that will reduce liking, and increasing wanting in the same context. As a result, an unhappy individual will obsessively look for food comforts orchestrating a series of feeding behaviors aimed at remedying all kinds of ailments and anxieties. This can become reminiscent of drug addition: a great deal of wanting despite very little liking.
Meal timing
Secretion of hormones associated with optimum feeding is circadian. Expression of genes affected by the hormones needs to be synchronized to separate catabolic and anabolic phases of the circadian cycle. The clock genes that regulate the levels of glucose, insulin, and other factors essential for the function of the appestat need to work in synchrony, and their clock phase in the liver, the pancreas, and the adipose tissue may all be in a set of feedback loops requiring well-established and well-pronounced circadian periodicity (see: details).
There is a great deal of evidence showing that the peak circadian release of ghrelin or leptin can be modified by meal timing. Restricted feeding can magnify circadian effects (see: Food anticipatory activity can be conditioned into a circadian phase). On the other hand, research shows that optimum timing of the release of glucocorticoids, or insulin has a powerful impact on the amplitude of the circadian gene expression. This implies that the timing of meals may have a monumental impact on health and longevity.
Meal timing can, to a degree, result in anchoring of physiological variables involved in feeding in the circadian cycle. In other words, feeding schedule may be somewhat adaptable. Most importantly, the rhythms of cortisol and leptin can be decoupled. Research on circadian gene expression may indicate that this kind of decoupling may reduce the efficiency of food processing, anabolic functions, and the amplitude of the circadian rhythm. Moreover, while circadian rhythms are robust, adaptations to meal timing tend to fade in days. This implies the involvement of low-stability memories. Thus meal timing adaptations must be considered secondary to the circadian optima.
While cortisol is a circadian marker, leptin is not. Shifts in meal timing may result in shifts in ghrelin and leptin secretion without a significant effect on the circadian cycle. Gastric circadian clock can shift in phase in reference to the hypothalamic oscillator. Food anticipatory activity cannot be blocked or induced by ghrelin alone, which indicates a complex mechanism, which is hard to control extrinsically. In a similar fashion, adipocyte oscillator can be inverted by rest-phase feeding. Food intake is a powerful determinant of leptin levels that may be entirely flattened in times of prolonged fasting. Like ghrelin, leptin alone does not determine food anticipatory activity. Whether the decoupling of the oscillators is harmful or part of a natural adaptation is hard to say. It seems safer to have all variables synchronized naturally on a schedule that emerges in prolonged ad libitum feeding.
If we feed rats during their rest phase, the cortisol rhythm becomes biphasic. Could this fact be used to enhance human biphasic nature with benefits for brainwork?
I suspect that finding the right formula for meal timing may be essential for the optimum diet, body weight control, and a healthy circadian cycle. However, most of research have been done on mice, while humans are biphasic, diurnal, and their adaptation processes proceed along a different trajectory on a different timeline (see: Brain conceptualization in development). There is no doubt though that circadian disruption can lead to obesity, and working in the night is sure not a hunter-gatherer habit (see Table 1).
As of Nov 9, 2020, I believe that time-restricted feeding (TRF) based on an approximation of one-meal-per-day schedule without caloric restriction is the right way to go. Circadian synchrony, intermittent fasting, and ad libitum feeding seem to be the key to healthy nutrition. I date this claim because the inflow of new data, and ideas seems to be accelerating. I may be wrong. For the evolution of my reasoning and eating habits see: Circadian diet
Calorie restriction
There is a great buzz about how calorie restriction (CR) might increase longevity. However, how do we define restriction? Any meaningful definition of "restriction" must involve a combat against one's own appetite system. As the main premise of my reasoning, and the origin of that entire text is that we should never engage in a combat against our own biological needs (as perceived by the brain), the concept of calorie restriction seems very unappealing. In addition, one of the side effects might be a depressed mood, which is a mortal enemy of productivity (see Minnesota Starvation Experiment). However, there is a possibility that calorie restriction involves the same mechanisms as intermittent metabolic switching (IMS). In mice, there is a great deal of evidence to show that fasting recapitulates the benefits of calorie restriction, while fasting might be a natural expression of lifestyle (for example, we naturally fast during sleep). In sum, I would never engage in calorie restriction unless there was good evidence that humans (or mice) live longer in CR, and the effects cannot be substituted with a healthy natural IMS schedule (intermittent fasting).
Even if I could get a few years of life but had to live that life with my mind distracted by the need to restrict my appetites, I would rather take high productivity option. The length of life seems secondary to one's actual ability to accomplish things of value. Minnesota volunteers had an awful attention span due to fantasizing about food. Similarly, too many of my past notes on my work speak of meals, reducing meals, substituting meals, the effects of meals, etc. The purpose of compiling all my knowledge into an overarching philosophy is to eliminate one big source of distraction in life. Paradoxically, one of the key problems in appetite control is reward deprivation. Dieting and worrying about dieting are counterproductive for weight management, and the ultimate goal: healthy living.
Jack Lalanne insisted that his death would ruin his reputation. By my standards, dying at "only" 96, LaLanne certified his lifestyle pretty good. In contrast, Roy Walford, who sparked my own interest in calorie restriction, did a lot of damage to his aura by dying at the young age of 79.
As some researchers would disagree with me on metabolic grounds (example), Lalanne's physique seem so much more appealing than that of emaciated Walford. Perhaps that's one bad habit I got from school, but I cannot help but admire good muscle. Yesterday's Mike Tyson at 54 (against Roy Jones on Nov 28, 2020), did more to my determination to exercise than a hundred articles on the science of physical effort. You can be 50+, 100kg, and still look good!Ego depletion
Ego depletion is the gradual and progressive exhaustion of mental resources needed to exert willpower. It is a popular concept in the science of addictions. In "food addiction", combating one's appetites leads to ego depletion as well. All forms of dieting undermine our will power and our creative resources. In this text, I insist that micromanaging diets is a wrong strategy, but if my argument is unconvincing, one should also realize that dieting undermines creativity. It is not that the brain functions less efficiency as a result of missing nutrients. Ego depletion is of more tangible significance.
The concept of ego depletion is considered unproven and controversial. If you question it, you are more likely to be a slow "depleter". This biased study makes a different claim. Be your own judge.
The idea of ego depletion comes from a genius mind of Roy Baumeister who came up with dozens of other fantastic ideas in psychology.
Ego depletion is easily proven on the grounds of neuroscience. Mental fatigue is a fact. It is proportional to the expense of creative and computational energy. Self-control is a result of mental computation. Combatting one's urges with will power is costly. Any combat that is not part of creative work is interfering with productivity. This is why creative slots should be free from self-discipline, and be dominated by the quest for creative pleasure. Creative pleasure provides the best criterion for maximizing creative productivity.
As I write these words, I am in a creative slot around midnight. Well rested, well fed (past my last meal) and entirely focused on the idea. There is no distraction caused by the thoughts of the last meal. There is no inflow of new information from social media. The only factor of self-discipline that will step in later on is the alarm in Plan that will tell me there are a few other things to do today. This approach provides full focus, maximum creativity, and the only form of depletion is the gradual waning of mental energy that is a natural effect of mental fatigue before sleep.
Interestingly, Baumeister proposed that self-control is like a muscle. He is right. This is why the marshmallow test is great fun to watch, but its predictive powers are limited by the trainability of self-discipline.
Intermittent fasting
Intermittent fasting is a newly popular approach to weight loss, and improved health. It is said to provide advantages of improved body composition, cognitive benefits (incl. neurogenesis), improved lipid and carbohydrate metabolism, and improved response to stress and exercise. According to Mark Mattson, the quintessential benefits of intermitted fasting rely on the concept of intermittent metabolic switching (G-to-K metabolic switch, i.e. from glucose to ketone fuel)(review).
Time-restricted feeding (TRF) is a form of fasting in which a longer daily abstinence of food is employed. It has been part of human life for millennia.
When the timing of food restriction is chosen optimally, TRF can increase the amplitude of the circadian cycle, and assist in the synchronization of the master clock, the liver clock, and other peripheral oscillators, esp. in conditions of low light such as winters (see more: review, and Food as zeitgeber).
Fasting that lasts more than 24 hours may also be highly beneficial, but it involves the risk of bad conditioning.
There are many alternative explanations for why fasting is superior to eating less, but one of the central reasons may lurk in the brain. The entire nutritional conditioning must be free from anxiety. The brain must be reassured on a regular basis that each fasting period is followed by times of plenty. Otherwise, bad conditioning may follow. The brain may look for ways to cheat the diet imposed by the rules of self-discipline.
Intermittent fasting and cancer
Encouraging news from research on intermittent fasting suggests that it may have some good effects in preventing cancer:
Chronic caloric restriction (CR) has powerful anticarcinogenic actions in both preclinical and clinical studies but may be difficult to sustain. As an alternative to CR, there has been growing interest in intermittent fasting (IF) in both the scientific and lay community as a result of promising study results, mainly in experimental animal models
For more see:
- Effect of fasting on cancer
- Intermittent Fasting in the Prevention and Treatment of Cancer
- Fasting and cancer
- Cancer Intermittent Fasting May Supercharge ‘Natural Killer’ Cell To Destroy Cancer
Weight loss factors
Exercise
Exercise is vital for good health, however, its role in weight control is largely misunderstood. Exercise is not sufficient to burn enough energy to significantly affect energy balance. Moreover, exercise is orexigenic and energy spent is likely to be compensated by energy consumed. However, exercise exerts multiple influences, incl. a positive hormonal impact on body composition and a potential to affect the appestat through the overall sense of well-being.
Junk food
Junk food is food that is poor in nutrients. As a result, junk food tends to smuggle excess calories while the brain attempts to meet all nutritional needs of the body.
Dr Guyenet observed that nothing makes rats as fat as human junk food. By analogy to Alexander's research, we should better check if the same would be true in the wild or at least in a rat park. Analogously, daycare is a great place to induce kids to consume junk food. If reward deprivation would be the source of the imbalance, junk food, narcotics or computer games are falsely blamed for what we do to our children. It would be interesting to ask true hunter-gatherers if they instantly love pizza. I would rather guess they would need to learn to love it. Would they not get instantly scared by the burn of the spices, or suspect smells they never experienced?
I doubt junk food is of major significance in designing optimum diet. Junk food is most likely to be consumed as form of reward compensation or out of habit. It is most dangerous when it is introduced early in little children without providing alternatives. A simple solution is not to eat it, and if cravings make it hard, junk food should be conditioned out incrementally. To solve the problem of junk food in society, we should look for the causes of reward deprivation and chronic stress. Abstinence from junk food is of little help in cases when the appestat asks for a higher level of fat deposits. The brain will just find a way around.
Stress
Chronic stress and sleep deprivation belong to leading causes of the malfunction of the appestat. Those elements of the modern unhealthy lifestyle should be prime targets in the epidemic of obesity. Unhealthy lifestyle is often an effect of limited freedom, which begins in childhood (see: compulsory schooling). Margriet Westerterp‐Plantenga noticed (source):
We conclude that acute psychological stress is associated with eating in the absence of hunger, especially in vulnerable individuals characterized by disinhibited eating behavior and sensitivity to chronic stress
Nutritional conditioning
Conditioning is essential for healthy eating. For many people, including children, eating sweets is a comfort, a vice, and a problem. I do not eat sweets. I believe, I conditioned a dislike for cakes and sugar. My story serves as an important inspiration for the entire model of optimum diet. The response to food can be changed by the power of habit.
Giving up sweets and cakes
As of 1994, I noticed an increase in my weight. I did not like it. It was probably around that time I tried to eat less sweets. Over the years, this process made me give up all sweets and cakes and treat them as unhealthy food. I am not sure if it took 25 years to develop that form of conditioning. Perhaps it can be developed in a year? The process was probably gradual and subconscious. Thinking about a creamy cake brings a hint of nauseous thoughts. I never overate. I never felt nauseous while eating. This must then be a figment of mind. Each time I see people eating cake, I think "they are doing harm to themselves". My conditioned dislike must have been brought by negative thinking and abstinence. What would happen if I tried some cake today? I am not sure. I think I tried and I liked it, but I forgot the event. I am still well conditioned to dislike cakes.
Giving up sugar and sweeteners
However, when my weight started creeping up again upon return, I decided to retain my tea drinking tradition, but to replace sugar with sweetener. This made it easy to quit sugar for life. However, for a longer while, I needed a prop of aspartame to tolerate the taste of tea, and later coffee.
Only around 2009-2010, was I able to wean myself from the sweetener. Aspartame got too much bad press, the evidence was unclear, and I decided to err on the safe side, and give it up entirely. It did not take long to start enjoying coffee without sweetener. I drink it as a mix of black and green coffee with a bit of milk and love it. My departure from sweetened coffee was complete around 2010. In 2020, I started adding yerba mate to my coffee mix purely for its aromatic qualities.
Giving up morning snack
In 2020, my mind is conditioned to dislike cakes, sweets and sweetened coffee. However, I still like halva. If I combine the smell of coffee with the image of the packaging of my favorite brand, I experience cravings. This is why I do not keep halva at home. Instead of breakfast, I drink coffee in the morning. I adapted to the new situation and enjoy it. Despite short night sleep, I enjoy nice creative time in the morning. My breakfast is made of coffee.
Bad conditioning
We can condition in new healthy habits by minor incremental changes in the diet. If we gradually replace a not-so-healthy food with a substitute that is provably superior, we allow the brain to re-adapt, optimize the processing of the new food constellation, and learn to reward the new behavior. The brain may not be able to distinguish between good food and bad food. The army of receptors is imperfect. However, it can re-adapt to eating the new healthier option and then reinforce it by generating new the baseline reward, which is an equivalent of saying "good enough".
However, conditioning may also go in the opposite direction. We can gradually get to enjoy eating junk food. After a while, nothing but junk food may provide baseline reward. Even worse, we can condition the brain to panic and strike back when the nutritional input is inadequate. In case of dieting, that panic may produce preventive deposits of fat. This is a brain's way of saying: "It seems I may occasionally be deprived of sufficient energy input. This is why I better deposit more fat as soon as energy input grows back to normal". This is one of the key reasons why dieting may backfire.
A false claim says that we have evolved to always aim at storing fat for times of scarcity. If that was true, all kids would tend to get fat, and so would octogenarians. A substantial proportion of the population seems to be well regulated and maintain the same good weight level for life without ever limiting food intakes. That preventive fat storage however may be a conditioned response of the brain adapting to intermittent scarcity. This is why I like the idea of time restricted feeding as opposed to more disruptive forms of intermittent fasting (e.g. 5:2 fasting with two fasting days per week). While intermittent metabolic switching in a set circadian frame is definitely a welcome phenomenon, extending the fast beyond a natural effortless period may lead to bad conditioning.
I agree with Dr Fung that fasting is much easier than diet restrictions. I tried 9 days fast in 2014, and it was remarkably easy. However, I doubt regular fasting imposed by self-discipline can always be that effortless. Moreover, I believe my creative productivity might have been lowered during the fast. It was not strikingly observable, but observability might have been masked by the enthusiasm for the experiment. My 3 days long fast in November 1982 (74h) was far less successful and ended with no-so-nice digestive consequences (primarily due to errors in re-feeding).
There are more similar misconceptions that need to be considered when aiming for optimum weight. The number of weight loss myths in circulation is actually staggering, and most of them seem to be based on the misunderstanding of the role of the appestat. I was actually unwitting circulating one of those myths: "being cold is good for weight loss" (see the anecdote below). I realized my error only a few days ago while working on this text, which temporarily switched my mode of thinking from automatically reproducing repetitive stories to a bit of self-reflection.
Harm of dieting
Any form of dieting that requires will power and self-discipline may be harmful. Due to the possible war of the networks, controls systems overridden by "rational" decisions may be subject to injury, malfunction, and dysregulation. The only healthy way to maintain a healthy weight is a natural way, in which things come by instinct and appetite.
My own history of an effort to maintain a healthy weight is a good illustration of what we do wrong about dieting. It also explains the origins of this texts. When my weight hit 100kg during the Covid lockdown, I decided to use the best of my knowledge about the brain and control theory to solve the puzzle of healthy nutrition.
Age of unconcern
In youth, with minimum intervention, in conditions of scarcity, it is often easy to keep a healthy weight, and healthy control systems responsible for appetites.
Age of plenty
Healthy eating is not enough to keep a healthy body. Irregular sleep and stress can affect the appestat. As a result, the control systems will be affected by compensatory actions (e.g. to respond to reward deprivation, sleep deprivation, stress, circadian disturbances, etc.)
Perfect vacation
Farmer's lifestyle can be combined with a lifestyle demanded by a sedentary creative job. It seems possible to ensure good sleep, low stress, high productivity, and a healthy weight with no dieting.
- getting up late made it impossible to participate in the hotel breakfast
- morning creative work would be short (roughly 10 am to 2 pm)
- long jogging up the mountain, combined with a wooden-log workout, and diving in an icy self-made brook pool
- sizeable dinner served by the hotel
- 500 ml of brown beer (probably 2% alcohol)
- shower and nap
- 1000 ml of strong tea with sugar for "supper"
- long night of creative work (roughly 8 pm to 3 am) with only 1 liter of milk drunk around 22-23, and no food around
Note the habit of drinking beer after dinner, which would slow down its absorption. I later changed that to rehydration during exercise. In addition, I also soon permanently replaced tea with coffee as a form of kidney stone prevention.
I did not monitor my weight but it dropped to 82.5 kg after just two months (Jul 9, 1995)(probably 3-5 kg loss). This unusual lifestyle felt great. Good health, good creativity, and high productivity. It was probably my best lifestyle that would combine high productivity with good fitness without dieting.
Figure: Gorska Perla resort was a place where the outline of SuperMemo 8 was created (1995). Algorithm SM-8 was conceived in a small room with the opened window in the picture. Krzysztof Biedalak stayed in a different room for a short sub-period too (Google Maps)
Age of neglect
Age of dieting
Farmer's lifestyle
Farmer's lifestyle is probably the best bet for healthy nutrition and a healthy control of appetite with little or no effort. Regular sleep combined with moderate exercise, and a simple "one meal per day" formula can bring significant changes in weeks. We often hear that the appestat will always aim at healthy weight and a healthy level of fat deposits. However, my simple lifestyle experiment below makes it possible to make a bold claim: The appestat will aim at equilibrium that is lifestyle-dependent.
The set point or settling point models will apply for all environmental, behavioral, and physiological variables unchanged. However, changing any of those variables will affect multiple equilibria in biochemical, hormonal and neural control systems. This is why the "general intake model" would apply. For a discussion see: How genes and environments combine to regulate body adiposity.
In simpler words:
- waking up naturally after sunrise (usually around 5-6 am)
- mini-breakfast, mini-coffee and some reading (usually newspapers purchased on the way)
- walking out early and slowly towards the next destination
- swimming a lot on the way, talking to people, diversions
- solid major meal of the day at the destination (occasionally a smaller meal if there was a village near the coast on the way)
- tired evening reading until falling asleep naturally at an early hour with minimum use of artificial light (usually at around 21-23)
- my sleep is never regular, but it would average 7.4 hours per night during the trip
The biggest difference as compared with my perfect vacation of 1995 was the fact that I would not use a computer and not work over night with artificial light. My sleep rhythm was very close to "waking with a sunrise" model.
Depending on distances traversed, weather, and intensity of exercise, I would lose 200-300g in weight per day during the trip. I reached 83.7 kg on Sep 13, 2003, and never saw that number of the scales since. The intensity of exercise was less than my usual regime.
Upon return, I would quickly gain back 100g per day until reaching a new equilibrium. In the end, between April 2003 and April 2004, I started from and returned to a weight at the same level of around 92kg.
A striking observation is than that my lifestyle and the farmer's lifestyle had their own equilibria that made a roughly 8 kg difference. My 83-85kg equilibrium in a farmer's lifestyle required no dieting and no self-denial. As for 92kg norm, I am less sureAutomatic portion control
Using mathematical optimization, we can easily maintain stable weight or fat levels for life. All we need is (1) realistic targets, and (2) a bit of self-discipline. My own story, however, seems to indicate that a priori determinations of "optimum weight" or "optimum fat level" have very little to do with optimum health.
My program assumed we stick to a reasonably designed dream "eat what you like" diet that would be comparable in caloric intake and composition from day to day. In my diet application, you could input your target weight, or better yet, the total fat mass target. The output would be the portions expressed as percent. If fat levels exceeded the target, the portions would be cut. The bigger the deviation, the smaller the portions. It can be proven that this diet program will always work as long as significant departures from targets are penalized by starvation, i.e. for large deviations the portions need to drop to zero.
The equilibrium portions would oscillate above the target, and would express the difference between (1) body's needs for a specific lifestyle, and (2) the actual fat level goal. For example, if my lifestyle favored the weight of 91kg, and my target was 88kg, the portions might oscillate between 50-60%, and the weight might oscillate between 88.0 and 88.6 kg. All the oscillation would be a result of poor adherence to the rules, lifestyle changes, random chance, measurement error, etc. Some of my friends tried the application, but no one survived the regime of precise portion cuts.
With all the mathematical soundness, my diet program had a biological flaw. The application would generate a feedback loop: the more one cuts the portions, the more the body adapts to lower intakes. Those adaptations may not always be welcome. For example, the resistance to infections may drop when the immune system gets stingy for nutrients and energy. In my case, energy for marathons might sag, the propensity for injury might increase, thermoregulation might get worse, etc. If the body does not get what it wants, it will adapt to lower supplies, but the operation would be sub-optimum.
As a result of using my diet program, in 2007, portions would swing wildly from 40% to 100%, but would most often land between 70-80%. Each time I had a good success streak, I would tighten the targets slightly. In winter, I started hitting 20% portions more often. I also suffered a few exercise injuries that would not heal as well as expected. In 2008, I kept tightening my fat targets with excellent results, but my portions would rarely go above 50%. When they hit 15% on Dec 7, 2008, I could see that I am just pushing my body into areas it does not want to be.
The application was pretty efficient in keeping my weight in check. However, I suspected it was not as beneficial for health as I would want it to be. In the end, I gave it up using it for very prosaic reasons. My dream diet design would usually include: breakfast, lunch, dinner, evening coffee, and supper. If my breakfast included 50g halva, the application might give me a green light to eat only 93% portion: 46.5g. I do not have issues with estimations, however, how do I manage the remnants? What do I do with 3.5g of halva? Toss away? Keep it in the fridge? It is pretty unwieldy to eat 93% of your usual meals because meals are often measured by packaging (e.g. 1 liter of milk, would leave 70g of milk exposed for deterioration).
Automatic meal control
We can simplify automatic portion control by introducing a meal control. Instead of cutting portions, we can skip meals. This approach makes it possible to stick to realistic weight targets, and is much easier to execute than portion control. Meal control may have similar adaptation side effects are portion control. However, my own story explains how meal control lead me to a conviction that morning fast might be a good thing.
My prime concern in 2008 was the complexity of portion control. A daily battle with eating 23% or 68% portions was too cumbersome to be sustainable. I decided to simplify the system by splitting my meals into 9-10 subcomponents such as halva, potatoes, veggies, beer, etc. Instead of reducing portions, I would skip components. For example, halva might be first to go, dinner veggies would be the only meal left in most extreme departures from the goals. At the very worst, I would be a boring veggie eater, even if I could not get to my target weight.
My system proved simple, and efficient. However, it did not solve the problem of feedback loops of adaptation (see above). For 7-8 years I used the system with various modifications, inconsistent adherence, and with varying level of success. However, my research on neural aspects of brain control lead me to a conviction that all forms of executive control over the appestat may be harmful. I gave up dieting in 2017. My thinking was reaffirmed in that my weight stabilized at levels 6-8 kg higher than the "desired optimum", but my overall health, esp. propensity for injury have improved a great deal. Some of the improvement might have come from better strategies (e.g. I entirely gave up running in shoes in favor of running barefoot, I play football with younger players, I rarely run after winter swimming, etc.). However, taking correction for age, I am sure that giving up dieting improved my overall well-being.
Most importantly, my meal control approach helped me understand that the idea of one meal per day is not entirely insane. I used to live by the mantra: eat often, eat little (as recommended many dieticians). My meal control system helped me evolve to a point when I consider all morning meals as unnecessary or even harmful on days of heavy exercise. This might then be a case where executive control requires some self-discipline at first, but quickly leads to an adaptation and the epiphany: morning fast is a natural and possibly a desirable state. It does not need to be optimum for everyone, or even optimum for me. However, it is clear that the body can adapt and accept morning fast routine as sustainable, seemingly healthy and even enjoyable.
Natural feeding
While studying the problem of schooling, I drew an analogy between the harm of schooling and the harm of dieting. While I left schooling far behind and enjoyed an unprecedented freedom of learning, I was still a prisoner of "healthy diet". In 2017, I decided to quit all forms of dieting. Unfortunately, my weight started creeping up. At first I wondered what I do wrong. Then I wondered how can I figure out that I am doing anything wrong. Perhaps a bit of padding is a natural physiological thing for a guy who spends long hours on the computer, often working till the early morning. In the end, I decided to solve the puzzle of the brain's development optimization criteria, and the optimization of nutrition. This is how this article was born.
Circadian diet
I mentioned earlier than meal timing may be the key to healthy eating. Below I speculate on my own case. I look for pros and cons of specific habits. These are not recommendations. My notes can only serve as further inspiration with a few points of data that may be highly specific to my own lifestyle. My "circadian diet" will never be perfect unless I return to farmer's lifestyle. For that however, I love my work too much. As it involves computers, it may be hard to solve the problem of working late in the night. Secondly, my current 97 kg weight (November 2020) should be highly suspect. I can run ultra-marathons, which is reassuring, but I cannot stop thinking that being 85-87 kg would be more beneficial for longevity.
Over the decades, my own meal timing evolved into fasting in the first half of the day. From a normal breakfast eater, I moved towards morning fast. At first, due to midday exercise, I avoided bigger meals in the morning to make long-distance running easier. In the early 2000s, I would still consume a small high-calorie snack (e.g. 50g halva) for breakfast. However, over the last 4 years, I gave up that habit too. My impression is that the adaptation is pretty complete. My morning coffee is the only major caloric injection in the first five hours of the day. It is hard to say if such an adaptation can occur fast or it takes as long as it was the case with my own routine. However, I cannot point to any negative side effect of such an unusual habit. My mornings are the best part of the day in terms of learning, creativity and problem solving (this text is being written 80 min. after waking).
In my youth, my main meal would usually take place in the late afternoon. My breakfast would often be hurried due to schooling (e.g. only cocoa). My second breakfast would often be stolen (at school), or never purchased (to save money). Those were the days of scarcity and a slim body.
Late dinners were also my main meals during my best-documented best-health lifestyles in 1995 and 2003 described [here]. As of 2004, I am pretty consistent. I eat my main meal after the exercise slot and before siesta. However, I am puzzled by the fact that around midnight, I experience my circadian peak of appetite that makes it hard to survive without a meal. I suspect that my increased weight in recent years is associated with either (1) aging, (2) injury to control systems (due to dieting), or (3) sub-optimum meal timing, esp. snacking at midnight.
Each time I try to skip midnight snacking, I can clearly perceive a drop in productivity. My mind is clearly distracted by hunger. At the same time, snacking increases sleepiness, which does not seem to be associated with the circadian cycle. That sleepiness often goes away when I take on some exciting jobs late in the night. Those jobs may have little to do with my mainstream pursuits. As a rule, after midnight, I scale down all things related to my professional endeavors except some lazy education (e.g. walking associated with incremental video).
If my weight is too high, and I am still capable of finding a better balance, the keys to the puzzle can be found after midnight. What is the optimum intake of food in the evening, if any, and what is the optimum timing?Skipping breakfast
My breakfast is coffee. I naturally evolved towards skipping breakfast. It is an effortless habit that fosters better exercise performance. It stands in some contradiction to recommendations spawned by research. However, I do not plan to change that habit. My evolution and reasoning is presented as a personal anecdote below. I recommend texts by Dr Jason Fung (e.g. The Tyranny of Breakfast). Longevity expert Dr David Sinclair is a fervent proponent of a schedule with a single major meal and 16-18 hour fasting window (see: interview).
Once I started living life in closer agreement with my physiology, I noticed that I am rarely hungry enough in the morning to eat breakfast. Nighttime fast does not dissipate quickly enough. As I always exercise as soon as in the 4th to 6th hour of waking, eating before a jogging or a football match does not make much sense. It always negatively affects performance. When I started skipping breakfast for the sake of calorie restriction, I discovered that life without breakfast seems superior. Neither my weight nor my lifestyle are good enough to model, and nobody should take my claims as a recommendation (perhaps Martin Berkhan would be more convincing, esp. that he can post his well-chiseled pictures along his posts).
For me, skipping breakfast is an outcome of natural nutritional evolution. These days, I avoid dieting. I stick with habits that are largely natural and pretty comfortable. My breakfast is coffee, and it feels great. For those who have doubts about skipping breakfast, I recommend lectures by Dr Jason Fung who observed that despite an overnight fast, we are least hungry at the time of breakfast (e.g. see: Circadian fasting). This is the easiest way to extend the fasting period into a nice healthy stretch (without the need for disruptive fasting days). Among important Fung claims is that breakfast does not seem to help reset the circadian cycle, which may be an important argument for those who tend to work late (like myself). In addition, if children do not like breakfast, we have a strong indication it is not as natural as your average mom would claim.
In search for research arguing for the importance of the breakfast, I noticed it always seems to draw conclusions based on assumptions divorced from ancestral lifestyle. For example: two groups of weight loss patients eat isocaloric meals. Those who eat more in the morning lose weight faster (source). Does it mean that breakfast is superior? Perhaps dinner is the time of better processing? If we mix breakfast with sand, we can get the exact same effect, and yet nobody would recommend sand in the diet. As for the levels of hormones in response to meals, there is always a risk of confusion. Are sharp spikes an effect of systemic overshot (poor response), or a good match with the circadian cycle (perfect response)? A higher dropout rate for diets with later meals might be a good indicator, but it may be correlated with well-conditioned habits the participants bring in into the experiment: the bigger the departure from their usual routine, the bigger the risk of a drop out. Instead of focusing on weight loss, we need to study ad libitum feeding to get good answers about the physiology of meal timing. In a more natural setting, the breakfast group might compensate at dinner time and actually gain weight. When I read about obesogenic factors, I always look for the possibility of good adaptation and efficient processing. Last but not least, for me, the most painful is the absence of data on the impact of siesta on optimum feeding. This explains why so much of my reasoning is based on modeling and self-experimentation.
Any research that correlates skipping breakfast with obesity needs to take into account the lifestyle. We all know people with stressful mornings that have no time for meals (I was one). This includes most of the teen student population. We all know people who skip breakfast to lose weight (I was one). In such cases, the root of the correlation stems from a deeper problem that may have nothing to do with meal timing. Healthy people do not need to diet.
My whole reasoning may be biased by the fact that I never miss exercise before dinner. This is why I do not want to bother my digestive system before an effort. I am also not too troubled with an increase in ghrelin or hunger. Hunger is never an issue during exercise. Extra cortisol or adrenaline in the morning I take in good part for better alertness and creative productivity.
I have no doubt that skipping breakfast has a great impact on my morning creativity and on my exercise performance. I do not plan to change that habit due to occasional research showing benefits of breakfast. If it is effortless, it cannot be that bad, I believe. I would need a strong physiologic argument against my habit. Jason Fung got it all figured out and that part of my diet will remain unchanged until significantly new data arrives. However, if you are young and slim, and your creativity is great, change nothing. Stay natural. The biggest mistake we all make is to micromanage health, micromanage routines and habits, etc. Once we condition the mind to do bad things, it is hard to undo it. If I am looking for optimal solutions, it is because I have a long history of errors that may affect my productivity in the long runMeal of the day
A well-timed major meal preceded by a period of fasting and exercise has a tremendous power of increasing the circadian amplitude and all associated adaptation benefits (source). A dominant major meal is well ingrained in most cultures incl. ancestral tribes. For a typical sun-synchronized lifestyle, recommendations vary from 1 pm to 10 pm.
I never bothered to record my meals like I record my sleep episodes. Today, I wish I had the data. I could swear that turkey makes you sleep better indeed (just a few highly convincing points in my memory). Despite lack of hard data, my practice of good napping is more than 20 years long and my concept network stores a generalized stable trace of many data points. My trust in the combination of a major meal and a siesta is so deep that I started looking for asymmetries between the first half and the second half of the day. Perhaps night should also be preceded with a meal. A bit of self-experimentation quickly disabused me from that idea. Most physiologists agree that the gut needs to rest in the night, but I was too curious and had to try. As late meals are a bad idea, I might have finally found the real reason for human biphasic nature. Perhaps a mid-day slump is supposed to discourage moving around while digesting? The fact that siesta helps survive mid-day heat is often mentioned by those who seek an explanation, but in my case, the slump seems to be even deeper in the midst of winter (possibly due to the impact of low light on alertness). For me, the meal of the day is a no brainer. My dinners are relatively small, but combined with a great deal of veggies of all sorts. I like to say that the meal is too small to reduce, and too big to size it up. It is because it is relatively low on calories and high on volume. Just perfect! My mix instinctively chosen set of macronutrients indicates that I go against Guyenet's principle of reduced palatability. By combining veggies with carbs, proteins, and fat, I make the main meal delicious and satisfying. I never plan to change that practice. It has been ingrained as a rock-solid habit. I know of no side effects. I can show that I can easily skip the main meal without much change for the appetite in the evening, however, the ultimate anabolic benefits are so clear that skipping is not the type of intermitted fasting I would ever want to adopt.
By all my best calculations, the circadian puzzle can easily be solved. The optimum timing should be right before the siesta. For me, brushing teeth or a shower make for a break long enough before the rest, and never found it digestively problematic to move away from the table directly to bed. If optimum nap comes at 7-8th hour of waking, the major meal should take place 6.5-7.5 hours from natural waking (Phase 7). In that puzzle of optimum circadian timing, I see no room for much change, but if you disagree, drop me a line.
I always call my major meal "a dinner", but in Mediterranean habits it may also be called "lunch", while snack-sized "dinner" is reserved for the evening meal. My musings on the optimum diet have many points of doubt, but the main meal before siesta is one of the sturdiest claims about optimizing meals I can makeEvening meal
Most people consume an evening meal. However, lots of research seems to point to late meals as one of the contributing causes of obesity. Some reassurance may come from the fact that centenarians often eat modest meals in the evening, and the practice of a late dinner is pretty common in some cultures well-known for healthy eating habits (e.g. in the Mediterranean). In my deliberations below, I looked back into my own habits and concluded that an evening meal may simply be hard to avoid in a lifestyle aimed at high productivity. It seems to be an expression of physiological needs that may not be easily changed with deliberate conditioning. Late meals may make it hard to reduce one's waistline, however, I am not sure how I might avoid them without violating my principles of life in compliance with human biology. Update 2024: I start leaning towards a belief that it is better to consume a bigger evening meal earlier than a smaller meal later. Extending the fasting window seems to be a priority, while later meals might lead to a greater appetite and a greater disparity between intents and outcomes. I am currently experimenting with Phase 12 evening meal (while previously adhering rather to Phase 16). That provides for a four-hour feeding window. See Dr Panda interview for the rationale
I seem to reach my peak level of appetite for food between 23:00-1:00 am, i.e. 2-5 hours ahead of the bedtime. It is clear that it is very hard to fast in that period without a detriment to productivity. On the other hand, a single meal would suffice to run the second half of the day without being hungry.
During my best periods in 1995 and in 2003, I did not fast in the evening either. In 1995, I would "snack" on one liter of milk. In 2003, my dinners came relatively late in reference to the waking hour.
I have decades of detailed notes on my evening snacking, but no coherent system and no clear conclusions emerge. A single evening meal is a habit well ingrained in the Mediterranean cultures. A single evening meal would definitely solve my hunger and productivity issues.
What would the optimum timing be? My main meal is easily determined by the optimum timing of the siesta, but the evening meal is much harder to position. Here are the prime option:
- Early: Meal that accompanies or follows my evening coffee slot. That would nicely provide a very long fasting window of 19-22 hours
- Middle: Meal that hits my peak hunger slot. That would seem most natural
- Late: Late meal that would match the first half of my day. Perhaps it would require some night-time exercise for symmetry?
It took just a few days of experimentation to show that early and late meals in the evening slot are a bad idea. In short, I can immediately sense digestive issues. For example, 500 ml coffee combined with a meal seems to linger in a bloated stomach. That's a clear distraction and a hit against productivity. (update 2024: this conclusion might be premature because just an hour later the outcomes might be very different while still qualifying for an early evening meal and a long fasting window)
Very late meals are generally considered harmful, and I could immediately see some negative side effects, incl. lowered quality of sleep. I experimented with late meals in the past when writing Curing DSPS and insomnia and concluded that they result in shortened sleep. My experiments were short-lived due to negative side effects, and I was not able to see if late meals produce the expected phase shift. For relevant research, I recommend all works by Satchidananda Panda (e.g. When you eat matters, not just what you eat).
As for late meals at peak appetite, I have many indications that they improve the timing and the quality of sleep in my own case. My chaotic snacking usually reflects the appetite. As such, I have a lot of points of data dispersed here and there.
My cursory experimentation seems to have then solved the last puzzle for me. Evening meal should come at peak appetite. It is then absorbed easily. It is well anticipated and quickly forgotten. It takes minimum time and minimum planning (just a tiny slot in Plan). My fasting window will then span 14-18 hours, which I gather is still pretty impressive by the standards set by the practitioners of intermittent fasting. Note that this fasting stretch is marred slightly by milk in coffee (protein), and beer during exercise (carbs/alcohol).
By monitoring my appetite ideation, and the efficiency of absorption, I timed my peak of appetite at Phase 13-14. Interestingly, in Argentina, dinner comes at 21:00-00:00, which is roughly the same phase! It is not much different in Italy, Spain or Greece. If you come from those places, send me the pros and cons and other details of that practice. Similarly, dr Fung recommends a small meal in the evening, and he also refers to the traditional Mediterranean meal timing (with a room for siesta).
At this moment, fasting throughout the evening seems impossible without a detriment to productivity, but as habits are adaptable, I plan to see if I can gradually reduce the size of the evening meals without producing a new source of distraction.
As I write these words on Nov 27, 2020, I plan to consistently stay observant with my new schedule for a longer while. I will have a major meal after exercise (as always), and a minor snack at around midnight in a set dedicated slot with minimum "improvisation". It may take months to be able to report on the effects, however, staying consistent will be essential for getting good answers. My average weight was consistently hovering around 97.4 kg over the last 69 days (i.e. the period since the last pre-covid competitive 15 km race). I also keep my fat levels and muscle mass records. I do not quote those due to inaccurate measurement methodology that might be misleading. However, it will be important to see the trends. For example, if my mass keeps increasing due to an increase in muscle mass, I will rather not worry. I presume it should not be hard to stay below 97kg, and any number below 95kg will probably deserve to be called a success. I hope this is to be my way of losing some weight without dieting.
My updated optimum brainwork graph with optimum meal timing is not set in stone. If I turned out very hungry ahead of the evening meal, it would come earlier and provide the benefit of a longer fasting period:
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Figure: Example of optimized meal timing inspired by Mediterranean habits. One major meal comes in Phase 8, and directly precedes the siesta. Evening snack comes in Phase 16 (or earlier). In terms of intermittent fasting, in the presented example, the period without meals spans 16.5 hours. Important: each person's circadian cycle may differ in terms of phase, period and amplitude. The timing in the graph is exemplary and cannot be followed without a study of individual sleep data, health, metabolic profile, lifestyle, latitude, climate, exercise regimen, and many more. For example, for people who need more hours for night sleep, circadian phase may be lower. It is more important to make sure that last meal precedes sleep by no less than 2-4 hours. Sleep data derived from SleepChart. The chart is based on: Optimizing the timing of brainwork
Summary
Here are some key principles of the optimum diet:
- weight loss is not a good criterion in researching diets. Healthy eating may lead to better absorption and better anabolic processes
- the optimum diet must be sustainable for life. It cannot be like cramming at school, or speedy short-term preps for a marathon (see: Principles of optimum diet)
- there must be no struggles as these all indicate a potential war of the networks, which may endanger the health of the control systems involved in the appestat
- re-conditioning is possible an acceptable, and if it is to be used, it needs to be cautious and incremental (see: Nutritional conditioning)
- diet struggles and rapid re-conditioning may enhance pathological appetites (see: Spaced repetition in appetite control)
- occasional scarcity may be more obesogenic than unlimited access to food (see: Bad conditioning)
- obesity is primarily born from the compensatory responses of the appestat
- perfect harmony in the circadian cycle is necessary. So is the harmony of meal times and meal content in reference to the cycle (see: Circadian diet, and Natural creativity cycle)
- adherence to reasonable nutritional guidelines is important, but any major scientifically-based nutritional philosophy will do as long as all other points are met
- problems with stress or sleep must be resolved as these are the main obesogenic culprits in society (see: Science of sleep and Stress resilience)
- time-restricted feeding is superior to the oft-recommended "multiple meals per day" (see: Intermittent fasting)
- time-restricted feeding may be a superior variant of calorie restriction and intermittent fasting
- exercise is important as part of a lifestyle, not just as a way to burn calories (see: explanation)
- farmer's lifestyle is a great model for the ideal lifestyle that ensures optimum natural appestat control
- meal timing must be synchronized with sleep and exercise. See an exemplary schedule below:
Figure: Example of optimized meal timing inspired by Mediterranean habits. One major meal comes in Phase 8, and directly precedes the siesta. Evening snack comes in Phase 16 (or earlier). In terms of intermittent fasting, in the presented example, the period without meals spans 16.5 hours. Important: each person's circadian cycle may differ in terms of phase, period and amplitude. The timing in the graph is exemplary and cannot be followed without a study of individual sleep data, health, metabolic profile, lifestyle, latitude, climate, exercise regimen, and many more. For example, for people who need more hours for night sleep, circadian phase may be lower. It is more important to make sure that last meal precedes sleep by no less than 2-4 hours. Sleep data derived from SleepChart. The chart is based on: Optimizing the timing of brainwork