Some people think that obesity largely stems from a lack of willpower - either eating too much food, or eating the wrong kind of food. While this perspective may be valid in some cases, it's simply not true much of the time. I have seen many morbidly obese patients who, when questioned about their diet, claim to eat only modest portions of what most people would call "healthy" food. Many of them have tried every diet under the sun, and yet to their utter frustration, they remain obese. Seen within a traditional medical perspective, this appears to make no sense, and so either all of these people are lying about what they eat, or the traditional medical perspective is broken, or at least incomplete. I am for the latter option.
There is an obesity epidemic in the western world, and it is on the rise. Obesity is associated with a swarm of diseases such as diabetes, heart disease, stroke, and several kinds of cancer including colon and breast cancer, and it costs health systems a lot of money (1). Measurements based on body-mass index (BMI) show that as of 2013 about 75% of the US population was overweight (BMI 25 or greater) and 33% of the population was obese (BMI 30 or greater) (1,2). These numbers are more than double what they were twenty years earlier (3). The South Pacific Islands top the list for the most obese countries in the world, followed by the Middle East and the US (4,5).
Given these facts, it is fair to say that obesity generally signifies poor health, but before we proceed, let's carefully define health.
Most standard definitions of health focus on the absence of disease (6). Although this is indeed a necessary condition for health, it is not sufficient. Since a thing cannot be defined by the absence of something else, health can no more be defined by the absence of disease than the sun can be defined by the absence of darkness. A more specific definition is required.
Life is not static; it is a dynamic, perpetual balancing act between catabolism (breaking down the organism) and anabolism (building up the organism). There are many examples of this - in the blood, where the clotting system perpetually breaks down clots so that blood flows in vessels, yet builds up clots when one of those vessels is damaged; in the bones, where osteoclasts perpetually break down bone to release calcium into the blood when it is needed, yet osteoblasts build up bone when increased bone strength is required; and in the muscles, where the muscles are broken down to provide energy when needed, yet built up when more muscle strength is demanded. If the balance between catabolism and anabolism is lost, disease prevails - using the clotting system to illustrate this point, if there is excess catabolism (clot breakdown), bleeding disorders such as hemophilia occur, and if there is excess anabolism (clot building), clotting disorders such as coronary thrombosis occur (followed by heart attacks). It is this balance between catabolic and anabolic states that keeps life going, that keeps the organism "healthy."
Thus, we ought to define health as a physiological state in which there is absence of disease as well as a biological balance between catabolism and anabolism (7). If too much time is spent in catabolism then muscle atrophy occurs, and if too much time is spent in anabolism then obesity occurs. Seen this way, muscle atrophy and obesity are not actually diseases themselves, they are only symptoms of excess catabolism and anabolism, respectively. In the developing world, health is often compromised by too much time spent in catabolism, leading to the symptoms of muscle atrophy, susceptibility to infections, poor wound healing...the list goes on. In the western world, health is often compromised by too much time spent in anabolism, followed by the symptoms of obesity, insulin resistance, high blood pressure...again, the list goes on.
Health is often confused with fitness, which is the ability to withstand, recover from, and adapt to environmental situations and threats (7). Healthy people may not necessarily be fit, and vice versa. Consider long-distance runners, who may be extremely fit, but are not healthy; the scientific literature is littered with studies showing that long-distance runners are more likely to develop cardiovascular disease (8,9,10), long-term muscle damage (11), kidney dysfunction (12), and brain damage (13) compared to their less active counterparts (this is but a small sample of the harmful effects of long-distance running). Long-distance runners spend too much time in catabolism, and as a result suffer from reduced health despite their high fitness.
Remembering that health is a biological balance between catabolism and anabolism allows us to more accurately examine the problem that is driving the obesity epidemic in the western world today - chronic nutrient intake.
Chronic Nutrient Intake
There have been many attempts to solve the obesity problem through changes in diet. Traditionally, a diet refers to either restriction (reducing how much is eaten) or special kinds of food (changing what is eaten), or both, usually in order to lose weight (14). The familiar, dogmatic medical advice regarding how much is eaten - "eat regular meals but limit portion size" - is difficult to sustain and is rarely successful, with perhaps the most notable exception seen in Okinawa Island, Japan where people traditionally adhered to the Confucian practice of Hara Hachi Bu which advises eating to 80% full (15). The usual medical advice regarding what is eaten is also familiar to most people - usually something along the lines of "eat regular meals but less sugar and more vegetables and fiber" - and many have taken this further to advocate one of the many different commercial diets available, with some of the popular ones listed below (16).
- The Atkins diet (low carbohydrate intake, particularly refined carbohydrates). - The Zone diet (maintains a ratio of 40% carbohydrate, 30% fat, and 30% protein). - The Vegetarian diet (plant-based foods, but can be further subdivided based on whether honey, eggs, or dairy are consumed). - The Vegan diet (purely plant-based, often for philosophical or environmental reasons). - The Weight Watchers diet (has a social aspect, with regular meetings, group support, and a points system). - The Paleolithic diet (focuses on what the "caveman" would have eaten, such as meat, nuts, and berries, but no dairy, grains, or processed food). - The Mediterranean diet (the traditional diet of south Italy and Greece, mainly plant-based foods, cheese, yoghurt, fish, and red wine).
While most of the above diets certainly hold some merit and are supported to various degrees by the scientific literature, all remain controversial for one reason or another. More to the point, it is clear that limiting how much is eaten, or changing what is eaten, hasn't solved the obesity epidemic in the western world.
What is missing from the idea that health can be improved by changing either how much or what food is eaten is that neither of these strategies addresses the peculiar practice of regularly eating three meals a day, a ritual that is taken for granted and deeply entrenched throughout the western world. This regular meal eating leads to an abnormal situation of chronic nutrient intake, ensuring that the body remains in a chronic state of anabolism, with anabolic hormones such as insulin chronically elevated. The reason insulin remains chronically elevated with three meals a day is that assuming there is at least some carbohydrate or protein, which is usually a safe bet, insulin is produced with every meal, and stays elevated for up to six hours after each meal, so that even during the intervals between meals and for much of the night, the body remains in a state of anabolism. There's just not enough time spent in the catabolic state, not enough opportunities to break down molecules and cells that ought to be broken down. In other words, three or more meals a day is bad for health. It is chronic nutrient intake that is the health scourge of the western world, chronic nutrient intake that leads to an endless state of anabolism and the eventual symptoms of obesity, insulin resistance, and high blood pressure.
This is not to say that how much and what one eats are totally irrelevant to health - they're still relevant, sometimes very much so. The practice of Hara Hachi Bu, certain vegetarian diets, and diets extremely high in fat and low in carbohydrates (in which the whole idea is to keep insulin levels down) also allow for sufficient catabolism. However, since none of these strategies addresses the real problem of a lack of balance between catabolism and anabolism, they run the risk of solving the problem of insufficient catabolism by creating the opposite problem, that of insufficient anabolism. It's about balance, alternating states of catabolism and anabolism; they're both critical, and both need enough time to express themselves. Without addressing this lack of balance, changing how much or what one eats are not the ideal strategies for improving health.
If health is the goal, there must be a sufficient amount of time dedicated to both catabolic and anabolic states. Willpower, how much one eats, and what one eats are not the major factors driving obesity in the western world. It's about regular meal eating which translates to chronic nutrient intake, and insufficient time spent in the catabolic state!
Fortunately, there is a simple approach to addressing chronic nutrient intake and restoring the balance between catabolism and anabolism, called intermittent fasting, a way of eating that cycles between periods of fasting (catabolism) and eating (anabolism). There's more evidence in support of intermittent fasting than any of the other strategies mentioned above, and it's easier to implement too.
From an evolutionary perspective, humans evolved as hunter-gatherers for millions of years, and since food was not always freely available, hunter-gatherers were forced to evolve as intermittent fasters; regular meals throughout the day are an evolutionary abnormality, a blip in evolutionary history that only appeared over the last 10,000 years of agriculture. Despite the popular conception that their diet is largely plant-based, the majority of modern hunter-gatherer societies actually consume a meat-based diet, with 65% of their energy derived from animal sources (17). This is interesting, for even though most of their diet consists of animal protein and fat, which many of the popular diets above would deem to be unhealthy, multiple scientific studies show that modern hunter-gatherers are relatively free from obesity, diabetes, and heart disease (17). It is intermittent fasting that allows them to maintain a reasonable balance between catabolism and anabolism.
From a physiological perspective, there are innumerable scientific studies supporting the beneficial effects of intermittent fasting even for fasting periods as little as sixteen hours in laboratory animals and humans (18). Some of these effects are shown below.
(1) Body fat reduction.
Intermittent fasting promotes fat burning and weight loss in humans, with greater reductions in body fat compared to daily energy restriction in obese individuals (18,19,20,21).
(2) Disease prevention.
Intermittent fasting improves insulin sensitivity and reduces chronic inflammation in animals and humans, thus probably protecting against diabetes, heart disease, and stroke. In mice, intermittent fasting is superior to caloric restriction alone in terms of increased insulin sensitivity and increased neuron resistance to cytotoxic stress (22). Humans that switch from three meals a day to an intermittent fasting regime dispay reduced insulin levels, increased insulin sensitivity, increased metabolism of fatty acids, and elevated ketone levels (ketones are a derivative of fatty acids that are beneficial to and preferentially utilized by neurons in the brain) (18,19,21). Most major diseases such as heart disease and stroke involve chronic inflammation in affected tissues, and numerous studies show that intermittent fasting reduces this chronic inflammation (18).
(3) Longevity enhancement.
Animals maintained on intermittent fasting live considerably longer than those allowed to eat at will with conditions such as diabetes, cardiovascular disease, neurodegenerative disease, and cancer forestalled and in some cases reversed (18,23,24). Regarding cancer, intermittent fasting forces cells in the body to use fats and ketones for fuel; normal cells are metabolically flexible and can do this, but cancer cells are not metabolically flexible and must have glucose, or they die (18,25,26). In animals and humans, intermittent fasting induces mitochondrial biogenesis and prevents age-related declines in mitochondrial oxidative capacity in skeletal muscle, and it enhances the mechanisms for removal of damaged molecules and organelles, thus "cleansing" cells (18,25,26).
If it still sounds too good to be true, that's what Dr Michael Mosley thought before he got involved in this short BBC documentary about intermittent fasting, which can be seen on http://www.dailymotion.com/video/xvdbtt_eat-fast-live-longer-hd_shortfilms. He personally puts intermittent fasting to the test, with surprising results. It's worth watching.
Intrigued? Try it yourself. The easiest way to start is with daily intermittent fasting - fasting for sixteen hours or more every day. This can be achieved by skipping breakfast and eating normally between noon and 8 pm. Since most people don't eat at night they have already inadvertently fasted for twelve hours upon waking anyhow, so holding off eating for four more hours until noon is not that hard. During the sixteen hour fasting period, one can and should still drink water as well as other things like tea or coffee (no milk or sugar though). During the eight hour eating period, one can eat whatever they like - I find that eating two big meals is best, and I like to make one of them low in carbohydrate unless I have exercised beforehand. All in all it's an easy strategy.
If one is so inclined, they can also incorporate multiday fasting - fasting for two or more days in a row. These can be done once a month, or once every several months depending on the level of personal dedication. Four days of fasting seems to be a sweet spot - short enough to be practically achievable, yet long enough to switch to a full catabolic profile involving every organ in the body, from the intestines to the brain (27). One word of warning - make sure you maintain salt intake during these more extended fasts to prevent hypotension and fainting. Before trying multiday fasting, read up on it first and seek guidance from a professional if you have any doubts about if and how to proceed.
For most people, a healthy diet does not require a religious adherence to restricting calorie intake, nor does it require scrupulous attention to the foods that are eaten. Health is simpler than that - it's about timing meals appropriately so as to maintain the balance between catabolism and anabolism such that rather than worrying about how much you eat and what you eat, all you really have to pay attention to is when you eat. Your body will do the rest. In the considered analysis, intermittent fasting is the single best strategy for addressing chronic nutrient intake and obesity in the western world today, hands down.
It might sound hard, but it's really not - during the eating period, you can more or less eat what you want, and the fasting gets easier the more you do it. I encourage anyone to try daily intermittent fasting for a couple of weeks, and if you do, please tell me how it went.
Solace (inspired by Mike Hewitt).
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