Banting’s diet plays a pivotal role in the science of obesity—and, in fact, chronic disease—for two reasons. First, if the diet worked, if it actually helped people lose weight safely and keep it off, then that is worth knowing. More important, knowing whether “the sugary and starchy elements of food” are “really the chief cause of undue corpulence” is as vital to the public health as knowing, for example, that cigarettes cause lung cancer, or that HIV causes AIDS. If we choose to quit smoking to avoid the former, or to use condoms or abstinence to avoid the latter, that is our choice. The scientific obligation is first to establish the cause of the disease beyond reasonable doubt. It is easy to insist, as public-health authorities inevitably have, that calories count and obesity must be caused by overeating or sedentary behavior, but it tells us remarkably little about the underlying process of weight regulation and obesity. “To attribute obesity to ‘overeating,’” as the Harvard nutritionist Jean Mayer suggested back in 1968, “is as meaningful as to account for alcoholism by ascribing it to ‘overdrinking.’”
After the publication of Banting’s “Letter on Corpulence,” his diet spawned a century’s worth of variations. By the turn of the twentieth century, when the renowned physician Sir William Osler discussed the treatment of obesity in his textbook
The two constants over the years were the ideas that starches and sugars—i.e., carbohydrates—must be minimized to reduce weight, and that meat, fish, or fowl would constitute the bulk of the diet. When seven prominent British clinicians, led by Raymond Greene (brother of the novelist Graham Greene), published a textbook entitled
1. Bread, and everything else made with flour…
2. Cereals, including breakfast cereals and milk puddings
3. Potatoes and all other white root vegetables
4. Foods containing much sugar
5. All sweets…
1. Meat, fish, birds
2. All green vegetables
3. Eggs, dried or fresh
4. Cheese
5. Fruit, if unsweetened or sweetened with saccharin, except bananas and grapes
“The great progress in dietary control of obesity,” wrote Hilde Bruch, considered the foremost authority on childhood obesity, in 1957, “was the recognition that meat…was not fat producing; but that it was the innocent foodstuffs, such as bread and sweets, which lead to obesity.”