The Obesity Code: Unlocking the Secrets of Weight Loss (Why Intermittent Fasting Is the Key to Controlling Your Weight)

by Jason Fung

The standard prescription for weight loss is “Eat Less, Move More.” It sounds perfectly reasonable. But why doesn’t it work?

This leaves the possibility that the conventional advice is simply wrong. And if it is, then our entire understanding of obesity is fundamentally flawed. Given the current epidemic of obesity, I suspect that such is the most likely scenario.

Seventy percent of your tendency to gain weight is determined by your parentage. Obesity is overwhelmingly inherited.

The key assumption of the theory that reducing caloric intake leads to weight loss is false, since decreased caloric intake inevitably leads to decreased caloric expenditure.

CERTAINLY, EXERCISE HAS great health benefits.

Exercise is still healthy and important—just not equally important. It has many benefits, but weight loss is not among them. Exercise is like brushing your teeth. It is good for you and should be done every day. Just don’t expect to lose weight.

No wonder it is so hard to keep the weight off! Diets work well at the start, but as we lose weight, our metabolism slows. Compensatory mechanisms start almost immediately and persist almost indefinitely. We must then reduce our caloric intake further and further simply to maintain the weight loss. If we don’t, our weight plateaus and then starts to creep back up—just as every dieter already knows.

Insulin causes obesity—which means that insulin must be one of the major controllers of the body set weight. As insulin goes up, the body set weight goes up. The hypothalamus sends out hormonal signals to the body to gain weight. We become hungry and eat.

Obesity is a hormonal dysregulation of fat accumulation.

Does excess cortisol lead to weight gain? The ultimate test is this: Can I make somebody fat with prednisone? If so, that can prove a causal relationship, rather than a mere association. So does prednisone cause obesity? Absolutely! Weight gain is one of prednisone’s most common, well-known and dreaded side effects. This relationship is causal.

stress causes 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.

Reducing stress is difficult, but vitally important. Contrary to popular belief, sitting in front of the television or computer is a poor way to relieve stress. Instead, stress relief is an active process. There are many time-tested methods of stress relief, including mindfulness meditation, yoga, massage therapy and exercise. Studies on mindfulness intervention found that participants were able to use yoga, guided meditations and group discussion to successfully reduce cortisol and abdominal fat.

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.

Think about foods that people say they’re “addicted” to. Pasta, bread, cookies, chocolate, chips. Notice anything? All are highly refined carbohydrates. Does anybody ever say they are addicted to fish? Apples? Beef? Spinach? Not likely. Those are all delicious foods, but not addictive.

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.

Insulin resistance is Lex Luthor. It is the hidden force behind most of modern medicine’s archenemies, including obesity, diabetes, fatty liver, Alzheimer’s disease, heart disease, cancer, high blood pressure and high cholesterol.

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.

Should we eat candy or olive oil? This is the question of macronutrient composition, or “what to eat.” However, the persistence of insulin plays a key role in the development of insulin resistance, so there is also the question of meal timing, or “when to eat.” Both components are equally important.

The increase in eating opportunities has led to persistence of high levels of insulin. Snacks, which tend to be high in refined carbohydrates, also tend to cause high levels of insulin. Under these conditions, we should expect the development of insulin resistance.

Our own disastrous, misguided dietary changes since the 1970s have created the diabesity debacle. We have seen the enemy, and it is ourselves. Eat more carbohydrates. Eat more often. Eat breakfast. Eat more. Ironically, these dietary changes were prescribed to reduce heart disease, but instead, we’ve encouraged it since diabesity is one of the strongest risk factors for heart disease and stroke. We’ve been trying to put out a fire with gasoline.

IF YOU WANT to avoid weight gain, remove all added sugars from your diet. On this, at least, everybody can agree. Don’t replace them with artificial sweeteners—as we’ll see in the next chapter, those are equally bad.

instead of reducing the obesity, diet beverages substantially increased the risk of it by a mind-bending 47 percent.

The study found a 30 percent increase risk of cardiovascular events (heart attacks and strokes) in those drinking two or more diet drinks daily.

Artificial sweeteners are not good. They are bad. Very bad.

Despite having a minimal effect on blood sugars, both aspartame and stevia raised insulin levels higher even than table sugar.14 Artificial sweeteners that raise insulin should be expected to be harmful, not beneficial. Artificial sweeteners may decrease calories and sugar, but not insulin. Yet it is insulin that drives weight gain and diabetes.

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. Eating chemicals that are not foods (such as aspartame, sucralose or acesulfame potassium) is not a good idea. They are synthesized in large chemical vats and added to foods because they happen to be sweet and not kill you.

Yes, drinking diet soda will reduce sugar intake. But no, it will not help reduce your weight. This, of course, you probably already knew. Consider all the people you see drinking diet sodas. Do you know anybody at all who said that drinking diet soda made him or her lose a lot of weight?

Carbohydrates are not inherently fattening. Their toxicity lies in the way they are processed.

refining encourages overconsumption. For example, making a glass of orange juice may require four or five oranges. It is very easy to drink a glass of juice, but eating five oranges is not so easy. By removing everything other than the carbohydrate, we tend to overconsume what is left.

Our bodies have adapted to the balance of nutrients in natural food. By refining foods and only consuming a certain component, the balance is entirely destroyed. People have been eating unrefined carbohydrates for thousands of years without obesity or diabetes.

The key to understanding fiber’s effect is to realize that it is not as a nutrient, but as an anti-nutrient—where its benefit lies. Fiber has the ability to reduce absorption and digestion. Fiber subtracts rather than adds. In the case of sugars and insulin, this is good. Soluble fiber reduces carbohydrate absorption, which in turn reduces blood glucose and insulin levels.

short-term human studies suggest that vinegar may help reduce insulin resistance.27 Two teaspoons of vinegar taken with a high-carbohydrate meal lowers blood sugar and insulin by as much as 34 percent, and taking it just before the meal was more effective than taking it five hours before meals.

Potatoes, served cold and dressed with vinegar as a salad, showed considerably lower glycemic index than regular potatoes.

Type 2 diabetics drinking two tablespoons of apple cider vinegar diluted in water at bedtime reduced their fasting morning blood sugars.

researchers noted that consuming trans fats increased LDL (low-density lipoprotein or “bad” cholesterol) and lowered HDL (high-density lipoprotein or “good” cholesterol) in subjects.

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.

sucrose and high fructose corn syrup are exceptionally fattening, far in excess of other foods. Sugar is uniquely fattening because it directly produces insulin resistance. With no redeeming nutritional qualities, added sugars are usually one of the first foods to be eliminated in any diet.

Many natural, unprocessed whole foods contain sugar. For example, fruit contains fructose, and milk contains lactose. Naturally occurring and added sugars are distinct from one another. The two key differences between them are amount and concentration.

Dark chocolate with more than 70 percent cacao, in moderation, is a surprisingly healthy treat.

Studies on dark-chocolate consumption indicate that it may help reduce blood pressure,5 insulin resistance6 and heart disease.

Don’t replace sugar with artificial sweeteners, as they also raise insulin as much as sugar and are equally prone to causing obesity.

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 thinking about what to eat for breakfast, consider this: If you are not hungry, don’t eat anything at all. It’s perfectly acceptable to break your fast at noon with grilled salmon and a side salad. But there’s nothing inherently wrong with eating breakfast in the morning either. It is just like any other meal.

Eat whole, unprocessed foods at all meals, including breakfast.

moderate consumption of red wine does not raise insulin or impair insulin sensitivity, and therefore may be enjoyed.

The best drink is really just plain or sparkling water. Slices of lemon, orange or cucumber are a refreshing addition.

Due to its high caffeine content, coffee is sometimes considered unhealthy. However, recent research has come to the opposite conclusion,19 perhaps due to the fact that coffee is a major source of antioxidants,20 magnesium, lignans21 and chlorogenic acid.