Weight loss is a big business, and, since it’s rarely successful in the long term, it comes with a built-in supply of repeat customers. And doctors have been involved in the business one way or another for a long time. Some 2,000 years ago, the Greek physician and philosopher Galen diagnosed “bad humors” as the cause of obesity, and prescribed massage, baths, and “slimming foods” like greens, garlic, and wild game for his overweight patients. More recently, in the early 20th century, as scales became more accurate and affordable, doctors began routinely recording patients’ height and weight at every visit. Weight-loss drugs hit the mainstream in the 1920s, when doctors started prescribing thyroid medications to healthy people to make them slimmer. In the 1930s, the weight-loss chemical 2,4-dinitrophenol (DNP) came along, followed by amphetamines, diuretics, laxatives, and diet pills like fen-phen, all of which worked only in the short term and caused side effects ranging from the annoying to the fatal.
The national obsession with weight got a big boost in 1942, when a life-insurance company created a set of tables that became the most widely referenced standard for weight in North America. The Metropolitan Life Insurance Company crunched age, weight, and mortality numbers from nearly 5 million policies in the United States and Canada to create “desirable” height and weight charts. For the first time, people (and their doctors) could compare themselves to a standardized notion of what they “should” weigh.