THE OBESITY CODE by Dr. Jason Fung

• THE ART OF medicine is quite peculiar. Once in a while, medical treatments become established that don’t really work. Through sheer inertia, these treatments get handed down from one generation of doctors to the next and survive for a surprisingly long time, despite their lack of effectiveness.
• Obesity is defined in terms of a person’s body mass index, calculated as a person’s weight in kilograms divided by the square of their height in meters. A body mass index greater than 30 is defined as obese.
• In the science of nutrition, there is rarely any consensus about anything:
• A calorie is a unit of food energy used by the body for various functions such as breathing, building new muscle and bone, pumping blood and other metabolic tasks.
• Calories In is the food energy that we eat. Calories Out is the energy expended for all of these various metabolic functions.
• Throughout most of human history, obesity has been rare.
• All foods can be divided into three different macronutrient groups: fat, protein and carbohydrates.
• IT IS FAIRLY obvious that obesity runs in families.
• Seventy percent of your tendency to gain weight is determined by your parentage. Obesity is overwhelmingly inherited.
• Hunger is one of the most powerful and basic of human instincts.
• There is no survival advantage to carrying a very high body-fat percentage.
• There is an important difference between being fat and being obese. Obesity is the state of being fat to the point of having detrimental health consequences.
• In humans, evolution did not favor obesity, but rather, leanness.
• TRADITIONALLY, OBESITY HAS been seen as a result of how people process calories, that is, that a person’s weight could be predicted by a simple equation: Calories In – Calories Out = Body Fat This key equation perpetrates what I call the calorie deception.
• Caloric intake and expenditure are intimately dependent variables. Decreasing Calories In triggers a decrease in Calories Out.
• “A calorie is a calorie” implies that the only important variable in weight gain is the total caloric intake, and thus, all foods can be reduced to their caloric energy.
• All calories are not equally likely to cause weight gain.
• A calorie is simply a unit of energy.
• Hormones tightly regulate every single system in the body.
• The problem of fat accumulation is really a problem of distribution of energy. Too much energy is diverted to fat production as opposed to, say, increasing, body-heat production.
• Calories In and Calories Out are highly dependent variables.
• Losing weight triggers two important responses. First, total energy expenditure is immediately and indefinitely reduced in order to conserve the available energy. Second, hormonal hunger signaling is immediately and indefinitely amplified in an effort to acquire more food.
• Weight loss results in increased hunger and decreased metabolism. This evolutionary survival strategy has a single purpose: to make us regain the lost weight.
• Let me state it as plainly as I can: “Eat Less” does not work. That’s a fact. Accept it.
• When it comes to weight loss, exercise is just not that effective.
• You can’t outrun a poor diet.
• Exercise represents a stress on the body. Small amounts are beneficial, but excessive amounts are detrimental.17
• The overfeeding paradox is that excess calories alone are not sufficient for weight gain—in contradiction to the caloric-reduction theory.
• Increased caloric intake is met with increased caloric expenditure. With the increase in total energy expenditure, we have more energy, more body heat and we feel great.
• Eating more does not make us fat. Getting fat makes us eat more.
• Our body is not a simple scale balancing Calories In and Calories Out. Rather, our body is a thermostat. The set point for weight—the body set weight—is vigorously defended against both increase and decrease.
• The vast majority of obese people are not deficient in leptin. Their leptin levels are high, not low. But these high levels did not produce the desired effect of lowering body fatness. Obesity is a state of leptin resistance.
• Obesity develops over decades.
• Obesity is a hormonal dysregulation of fat mass. The body maintains a body set weight, much like a thermostat in a house.
• OBESITY IS NOT caused by an excess of calories, but instead by a body set weight that is too high because of a hormonal imbalance in the body.
• Hormones are molecules that deliver messages to a target cell.
• Insulin is a key regulator of energy metabolism, and it is one of the fundamental hormones that promote fat accumulation and storage.
• Insulin is a storage hormone. Ample intake of food leads to insulin release. Insulin then turns on storage of sugar and fat. When there is no intake of food, insulin levels fall, and burning of sugar and fat is turned on.
• Under normal conditions, high insulin levels encourage sugar and fat storage. Low insulin levels encourage glycogen and fat burning. Sustained levels of excessive insulin will tend to increase fat storage. An imbalance between the feeding and fasting will lead to increased insulin, which causes increased fat, and voilà—obesity.
• OBESITY DEVELOPS WHEN the hypothalamus orders the body to increase fat mass to reach the desired body set weight.
• The key to understanding obesity is to understand what regulates body set weight, why body set weight is set so high, and how to reset it lower.
• Insulin causes obesity.
• In type 1 diabetes, there is destruction of the insulin-producing cells of the pancreas, resulting in very low levels of insulin. Patients require insulin injections to survive.
• In type 2 diabetes, cells are resistant to insulin and insulin levels are high.
• Insulin causes weight gain.
• Type 1 diabetes is an autoimmune disease that destroys the insulin-producing beta cells of the pancreas. Insulin falls to extremely low levels. Blood sugar increases, but the hallmark of this condition is severe weight loss.
• THE RESULTS ARE very consistent. Drugs that raise insulin levels cause weight gain. Drugs that have no effect on insulin levels are weight neutral. Drugs that lower insulin levels cause weight loss.
• Hormones are central to understanding obesity.
• Obesity is a hormonal, not a caloric imbalance.
• The crucial point to understand, however, is not how insulin causes obesity, but that insulin does, in fact, cause obesity.
• Long-term use of prednisone leads to an insulin-resistant state in a patient or even to full-blown diabetes.
• abdominal fat deposits are more dangerous to health than all-over weight gain.)
• Stress contains neither calories nor carbohydrates, but can still lead to obesity. Long-term stress leads to long-term elevated cortisol levels, which leads to extra pounds.
• SLEEP DEPRIVATION IS a major cause of chronic stress today.
• Getting enough good sleep is essential to any weight loss plan.
• Highly refined carbohydrates are the most notorious foods for raising blood sugars. High blood sugars lead to high insulin levels. High insulin levels lead to weight gain and obesity. This chain of causes and effects has become known as the carbohydrate-insulin hypothesis.
• Refined carbohydrates are easy to become addicted to and overeat precisely because there are no natural satiety hormones for refined carbs. The reason, of course, is that refined carbohydrates are not natural foods but are instead highly processed. Their toxicity lies in that processing.
• Insulin and obesity are still causally linked. However, it is not at all clear that high carbohydrate intake is always the primary cause of high insulin levels.
• The notion that carbohydrates are the only driver of insulin is incorrect. A critical piece of the puzzle had been neglected.
• Usually, obesity is a gradual process of gaining 1 to 2 pounds (0.5 to 1 kilogram) per year.
• THE HUMAN BODY is characterized by the fundamental biological principle of homeostasis. If things change in one direction, the body reacts by changing in the opposite direction to return closer to its original state.
• Insulin causes insulin resistance.
• The longer you are obese, the harder it is to eradicate.
• The longer you are obese, the more insulin resistance you have. Gradually, that insulin resistance will cause even your fasting insulin levels to rise.
• Persistent high insulin levels lead gradually and eventually to insulin resistance.
• The brain is not resistant to insulin. When high insulin levels reach the brain, the insulin retains its full effect to raise body set weight.
• Normally, insulin is released in bursts, which prevents the development of insulin resistance.
• Over time, insulin resistance induces the body to produce even more insulin to “overcome” the resistance.
• Insulin resistance requires persistently high levels.
• Eating more frequent meals does not aid in weight loss.
• The human body has evolved mechanisms to deal with prolonged periods without food. The body instead burns fat for energy, and blood sugar levels remain in the normal range, even during prolonged fasting, due to gluconeogenesis.
• The increase in eating opportunities has led to persistence of high levels of insulin.
• Increasing meal frequency does not result in weight loss.
• It is simply not necessary to eat the minute we wake up.
• There is simply no need to refuel with sugary cereals and bagels. Morning hunger is often a behavior learned over decades, starting in childhood.
• The word breakfast literally means the meal that breaks our fast, which is the period when we are sleeping and therefore not eating.
• The main problem in the morning is that we are always in a rush. Therefore, we want the convenience, affordability and shelf life of processed foods.
• The vast majority (73 percent) of children regularly eat sugary cereals. By contrast, only 12 percent regularly eat eggs at breakfast.
• Breakfast is the most important meal of the day—for Big Food.
• Are you hungry at breakfast? If not, listen to your body and don’t eat.
• To put it simply, you cannot eat more to weigh less, even if the food you’re eating more of is as healthy as vegetables.
• EXCESSIVELY HIGH INSULIN resistance is the disease known as type 2 diabetes. High insulin resistance leads to elevated blood sugars, which are a symptom of this disease. In practical terms, this means that not only does insulin causes obesity, but also that insulin causes type 2 diabetes. The common root cause of both diseases is high, persistent insulin levels.
• Despite the similarity in culture and genetics between populations in Canada and the United States, U.S rates of obesity are much higher.
• States with the most poverty tend to also have the most obesity.
• The increased palatability of food is not accidental.
• The majority of exercise is free, often requiring no more than a basic shoe.
• The government is subsidizing, with our own tax dollars, the very foods that are making us obese. Obesity is effectively the result of government policy. Federal subsidies encourage the cultivation of large amounts of corn and wheat, which are processed into many foods.
• The driving factor in obesity is insulin, and in many cases, the wide availability of refined carbohydrates.
• Childhood obesity also leads to adult obesity and future health problems, particularly cardiovascular issues.
• miserably as a remedy for adult obesity. Did the children learn how to eat a low-fat diet? Sure did. Dietary fat started at 34 percent of calories and over the course of the study, fell to 27 percent. Did they eat fewer calories? Sure did. The intervention group averaged 1892 calories per day compared to 2157 calories per day in the control group. Fantastic! The children were eating 265 fewer calories per day. They learned their lessons extremely well, eating fewer calories and less fat overall. Over the course of three years, calorie counters expected a loss of approximately 83 pounds! But did the children’s weight actually change? Not even by a little bit. Physical activity was no different between the two groups. Despite the increased physical education done in the schools, the total physical activity measured by accelerometer was not different—which should have been expected, given the known effect of compensation. Those children who were very active in school reduced their activity at home. Children relatively sedentary at school increased their activity once out of school. This study was vitally important. The failure of the low-fat, low-calorie strategy should have prompted a search for more effective methods of controlling the scourge of childhood obesity. It should have prompted soul searching for the underlying cause of obesity and how to rationally treat it.
• Thereafter, sugar-sweetened drink relentlessly declined in popularity. From 2003 to 2013, soft-drink consumption
• Sugar, more than any other refined carbohydrate, seems to be particularly fattening and leads to type 2 diabetes.
• Glucose is the main sugar found in the blood and circulates throughout the body.
• Whereas almost every cell in the body can use glucose for energy, no cell has the ability to use fructose.
• The bottom line is that excess fructose is changed into fat in the liver. High levels of fructose will cause fatty liver. Fatty liver is absolutely crucial to the development of insulin resistance in the liver.
• Fructose overconsumption leads directly to insulin resistance.
• INSULIN IS NORMALLY released when we eat.
• Balancing feeding and fasting periods over a day ensures that no net fat is gained or lost.
• Fructose overconsumption causes fatty liver, which directly produces insulin resistance.
• Sugar’s effects, as well as obesity, develop over decades, not days.
• IF YOU WANT to avoid weight gain, remove all added sugars from your diet.
• Despite reducing sugar, diet sodas do not reduce the risk of obesity, metabolic syndrome, strokes or heart attacks. But why? Because it is insulin, not calories, that ultimately drives obesity and metabolic syndrome.
• Despite having a minimal effect on blood sugars, both aspartame and stevia raised insulin levels higher even than table sugar.
• Caloric reduction is the main advantage of artificial sweeteners. But it is not calories that drives obesity; it’s insulin. Since artificial sweeteners also raise insulin levels, there is no benefit to using them.
• Insulin and insulin resistance drive obesity. Refined carbohydrates, such as white sugar and white flour, cause the greatest increase in insulin levels.
• Refining significantly increases the glycemic index by purifying and concentrating the carbohydrate. Removal of fat, fiber and protein means that the carbohydrate can be digested and absorbed very quickly.
• Today’s wheat is simply not as nutritious as in previous generations.
• FIBER IS THE non-digestible part of food, usually of a carbohydrate.
• Fiber has the ability to reduce absorption and digestion. Fiber subtracts rather than adds.
• Soluble fiber reduces carbohydrate absorption, which in turn reduces blood glucose and insulin levels.
• Western diets are characterized by one defining feature—and it’s not the amount of fat, salt, carbohydrate or protein. It’s the high amount of processing of foods.
• BOTH OBESITY AND type 2 diabetes are diseases caused by excessive insulin. Insulin resistance develops over time as a result of persistently high insulin levels.
• Blood glucose does not drive weight gain. But hormones—particularly insulin and cortisol—do.
• Carbohydrates are just long chains of sugars. There is nothing intrinsically nutritious about them.
• All foods, not just carbohydrates, stimulate insulin. Thus, all foods can cause weight gain.
• PROTEINS DIFFER GREATLY in their capacity to stimulate insulin,8 with dairy products in particular being potent stimuli.
• Animal proteins tend to cause you to feel fuller for longer, with whey having the greatest effect.
• Eating three extra servings of meat per day is associated with an extra pound in weight gain over one year, even after controlling for calories.
• It is difficult to significantly increase dairy proteins without resorting to whey protein shakes and other such artificial foods.
• Here’s a small tip for weight loss, one that should be obvious, but is not. If you are not hungry, don’t eat. Your body is telling you that you should not be eating.
• Heart attacks and strokes are predominantly inflammatory diseases, rather than simply diseases of high cholesterol levels.
• THE EVIDENCE ON a link between dietary fat and obesity is consistent: there is no association whatsoever. The main concern about dietary fats had always been heart disease. Obesity concerns were just “thrown in” as well.
• THERE ARE TWO prominent findings from all the dietary studies done over the years. First: all diets work. Second: all diets fail.
• There is no one single cause of obesity.
• Virtually all diseases of the human body are multifactorial.
• All diets work because they all address a different aspect of the disease. But none of them work for very long, because none of them address the totality of the disease.
• The long-recognized truth is that certain foods must be severely restricted, including sugar-sweetened beverages and candy. Other foods do not need to be restricted: kale or broccoli, for instance.
• Calories are only a single factor in the multifactorial disease that is obesity.
• SUGAR STIMULATES INSULIN secretion, but it is far more sinister than that. Sugar is particularly fattening because it increases insulin both immediately and over the long term.
• Candy is often little more than flavored sugar.
• Be aware, though, that if your goal is weight loss, your first major step must be to severely restrict sugar. Don’t replace sugar with artificial sweeteners, as they also raise insulin as much as sugar and are equally prone to causing obesity.
• Grazing is the direct opposite of virtually all food traditions.
• Simply ask yourself this question. Are you really hungry or just bored?
• There’s a simple answer to the question of what to eat at snack time. Nothing. Don’t eat snacks. Period. Simplify your life.
• In the diets of children under age eight, breakfast cereals rank behind only candy, cookies, ice cream and sugared drinks as a source of dietary sugar.
• A simple rule to follow is this: Don’t eat sugared breakfast cereal.
• Remember: the toxicity in much Western food lies in the processing, rather than in the food itself.
• GLUCOSE AND FAT are the body’s main sources of energy. When glucose is not available, then the body adjusts by using fat, without any health detriment.
• Fat is simply the body’s stored food energy.
• Regular fasting, by routinely lowering insulin levels, has been shown to significantly improve insulin sensitivity.
• FASTING IS DEFINED as the voluntary act of withholding food for a specific period of time.