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

by Jason Fung

We are not mice. We are not rats. We are not chimpanzees or spider monkeys. We are human beings, and therefore we should consider only human studies.

This is the cruel hoax. Eating less does not result in lasting weight loss. It. Just. Does. Not. Work.

But here’s the dismal truth: whether physical activity increases or decreases, it has virtually no relationship to the prevalence of obesity.

The overwhelming majority of total energy expenditure is not exercise but the basal metabolic rate: metabolic housekeeping tasks such as breathing, maintaining body temperature, keeping the heart pumping, maintaining the vital organs, brain function, liver function, kidney function, etc.

Diet does 95 percent of the work and deserves all the attention; so, logically, it would be sensible to focus on diet. Exercise is still healthy and important—just not equally important. It has many benefits, but weight loss is not among them.

Exercise represents a stress on the body. Small amounts are beneficial, but excessive amounts are detrimental.17

We eat, insulin goes up, and we store energy as glycogen and fat. We fast, insulin goes down and we use our stored energy. As long as our feeding and fasting periods are balanced, this system also remains balanced. If we eat breakfast at 7 a.m. and finish eating dinner at 7 p.m., the twelve hours of feeding balances the twelve hours of fasting.

Although we think it’s a universal truth, it’s really only a North American custom. Many people in France (a famously skinny nation) drink coffee in the morning and skip breakfast. The French term for breakfast, petit déjeuner (little lunch) implicitly acknowledges that this meal should be kept small.

It is simply not necessary to eat the minute we wake up.

The same thing drives obesity in the Pima Indians as in everyone else: highly refined carbohydrates. When the Pima replaced traditional, unrefined foods with highly refined sugar and flour, they became obese.

THE WORST OFFENDER, by far, is the sugar-sweetened drink—soft drinks, sodas and, more recently, sweetened teas and juices.

Natural fruit consumption contributed only small amounts of fructose to our diet, in the range of 15 to 20 grams per day. Things began to change with the development of high-fructose corn syrup.

Excessive fructose puts significant pressure on the liver since other organs cannot help.

IF YOU WANT to avoid weight gain, remove all added sugars from your diet.

Both agave nectar and sweeteners derived from Stevia are highly processed. In that regard, they are not any better than sugar itself—a natural compound derived from sugar beets.

Despite having a minimal effect on blood sugars, both aspartame and stevia raised insulin levels higher even than table sugar.

Artificial sweeteners may also cause harm by increasing cravings. The brain may perceive an incomplete sense of reward by sensing sweetness without calories, which may then cause overcompensation and increased appetite and cravings.

Conflicting reports such as these often generate confusion within nutritional science. One study will show a benefit and another study will show the exact opposite. Generally, the deciding factor is who paid for the study.

Insulin and insulin resistance drive obesity. Refined carbohydrates, such as white sugar and white flour, cause the greatest increase in insulin levels.

“Good” carbohydrates (whole fruits and vegetables) are substantially different from “bad” (sugar and flour).

After five years of follow-up, findings showed that total meat, red meat, poultry and processed meats were all significantly associated with weight gain,

Here’s a small tip for weight loss, one that should be obvious, but is not. If you are not hungry, don’t eat.

The toxicity lies not in the food, but in the processing.

The liver manufactures the overwhelming majority—80 percent—of the blood cholesterol, with only 20 percent coming from diet.

Cholesterol is a key building block in the membranes that surround all the cells in our body. In fact, it’s so vital that every cell in the body except the brain has the ability to make it. If you reduce cholesterol in your diet, your body will simply make more.