The Obesity Code. Jason Fung

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СКАЧАТЬ We choose to eat chips instead of broccoli. We choose to watch TV instead of exercise. Through this reasoning, obesity is transformed from a disease that needs to be investigated and understood into a personal failing, a character defect. Instead of searching for the ultimate cause of obesity, we transform the problem into

      •eating too much (gluttony) and/or

      •exercising too little (sloth).

      Gluttony and sloth are two of the seven deadly sins. So we say of the obese that they “brought it on themselves.” They “let themselves go.” It gives us the comforting illusion that we understand ultimate cause of the problem. In a 2012 online poll,¹ 61 percent of U.S. adults believed that “personal choices about eating and exercise” were responsible for the obesity epidemic. So we discriminate against people who are obese. We both pity and loathe them.

      However, on simple reflection, this idea simply cannot be true. Prior to puberty, boys and girls average the same body-fat percentage. After puberty, women on average carry close to 50 percent more body fat than men. This change occurs despite the fact that men consume more calories on average than women. But why is this true?

      What is the ultimate cause? It has nothing to do with personal choices. It is not a character defect. Women are not more gluttonous or lazier than men. The hormonal cocktail that differentiates men and women must make it more likely that women will accumulate excess calories as fat as opposed to burning them off.

      Pregnancy also induces significant weight gain. What is the ultimate cause? Again, it is obviously the hormonal changes resulting from the pregnancy—not personal choice—that encourages weight gain.

      Having erred in understanding the proximate and ultimate causes, we believe the solution to obesity is to eat fewer calories.

      The “authorities” all agree. The U.S. Department of Agriculture’s Dietary Guidelines for Americans, updated in 2010, forcefully proclaims its key recommendation: “Control total calorie intake to manage body weight.” The Centers for Disease Control² exhort patients to balance their calories. The advice from the National Institutes of Health’s pamphlet “Aim for a Healthy Weight” is “to cut down on the number of calories . . . they get from food and beverages and increase their physical activity.”³

      All this advice forms the famous “Eat Less, Move More” strategy so beloved by obesity “experts.” But here’s a peculiar thought: If we already understand what causes obesity, how to treat it, and we’ve spent millions of dollars on education and obesity programs, why are we getting fatter?

       ANATOMY OF AN EPIDEMIC

      WE WEREN’T ALWAYS so obsessed with calories. Throughout most of human history, obesity has been rare. Individuals in traditional societies eating traditional diets seldom became obese, even in times of abundant food. As civilizations developed, obesity followed. Speculating on the cause, many identified the refined carbohydrates of sugar and starches. Sometimes considered the father of the low-carbohydrate diet, Jean Anthelme Brillat-Savarin (1755–1826) wrote the influential textbook The Physiology of Taste in 1825. There he wrote: “The second of the chief causes of obesity is the floury and starchy substances which man makes the prime ingredients of his daily nourishment. As we have said already, all animals that live on farinaceous food grow fat willy-nilly; and man is no exception to the universal law.”⁴

      All foods can be divided into three different macronutrient groups: fat, protein and carbohydrates. The “macro” in “macronutrients” refers to the fact that the bulk of the food we eat is made up of these three groups. Micronutrients, which make up a very small proportion of the food, include vitamins and minerals such as vitamins A, B, C, D, E and K, as well as minerals such as iron and calcium. Starchy foods and sugars are all carbohydrates.

      Several decades later, William Banting (1796–1878), an English undertaker, rediscovered the fattening properties of the refined carbohydrate. In 1863, he published the pamphlet Letter on Corpulence, Addressed to the Public, which is often considered the world’s first diet book. His story is rather unremarkable. He was not an obese child, nor did he have a family history of obesity. In his mid-thirties, however, he started to gain weight. Not much; perhaps a pound or two per year. By age sixty-two, he stood five foot five and weighed 202 pounds (92 kilograms). Perhaps unremarkable by modern standards, he was considered quite portly at the time. Distressed, he sought advice on weight loss from his physicians.

      First, he tried to eat less, but that only left him hungry. Worse, he failed to lose weight. Next, he increased his exercise by rowing along the River Thames, near his home in London. While his physical fitness improved, he developed a “prodigious appetite, which I was compelled to indulge.”⁵ Still, he failed to lose weight.

      Finally, on the advice of his surgeon, Banting tried a new approach. With the idea that sugary and starchy foods were fattening, he strenuously avoided all breads, milk, beer, sweets and potatoes that had previously made up a large portion of his diet. (Today we would call this diet low in refined carbohydrates.) William Banting not only lost the weight and kept it off, but he also felt so well that he was compelled to write his famous pamphlet. Weight gain, he believed, resulted from eating too many “fattening carbohydrates.”

      For most of the next century, diets low in refined carbohydrates were accepted as the standard treatment for obesity. By the 1950s, it was fairly standard advice. If you were to ask your grandparents what caused obesity, they would not talk about calories. Instead, they would tell you to stop eating sugary and starchy foods. Common sense and empiric observation served to confirm the truth. Nutritional “experts” and government opinion were not needed.

      Calorie counting had begun in the early 1900s with the book Eat Your Way to Health, written by Dr. Robert Hugh Rose as a “scientific system of weight control.” That book was followed up in 1918 with the bestseller Diet and Health, with Key to the Calories, written by Dr. Lulu Hunt Peters, an American doctor and newspaper columnist. Herbert Hoover, then the head of the U.S. Food Administration, converted to calorie counting. Dr. Peters advised patients to start with a fast, one to two days abstaining from all foods, and then stick strictly to 1200 calories per day. While the advice to fast was quickly forgotten, modern calorie-counting schedules are not very different.

      By the 1950s, a perceived “great epidemic” of heart disease was becoming an increasing public concern. Seemingly healthy Americans were developing heart attacks with growing regularity. In hindsight, it should have been obvious that there was really no such epidemic.

      The discovery of vaccines and antibiotics, combined with increased public sanitation, had reshaped the medical landscape. Formerly lethal infections, such as pneumonia, tuberculosis and gastrointestinal infections, became curable. Heart disease and cancer now caused a relatively greater percentage of deaths, giving rise to some of the public misperception of an epidemic. (See Figure 1.1.⁶)

      Figure 1.1. Causes of death in the United States 1900 vs. 1960.

      The increase in life expectancy from 1900 to 1950 reinforced the perception of a coronary-disease epidemic. For a white male, the life expectancy in 1900 was fifty years.⁷ By 1950, it had reached sixty-six years, and by 1970, almost sixty-eight years. If people were not dying of tuberculosis, then they would live long enough to develop their heart attack. Currently, the average age at first heart attack is sixty-six years.⁸ The risk of a heart attack in a fifty-year-old man is substantially lower than in a sixty-eight-year-old man. So the natural consequence of a longer life expectancy is an increased rate of coronary disease.

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