The same could be asked about metabolic or hormonal factors, which also contribute to excessive adiposity, as Jerome Knittle of Rockefeller University explained in 1976, when he testified before George McGovern’s Senate Select Committee on Nutrition and Human Needs. “Infants born to diabetic mothers are heavier at birth, are relatively fatter and have a higher rate of subsequent obesity than infants of non-diabetic mothers of equal gestational age,” Knittle said. But if these physiologic factors make for fatter babies and subsequently fatter adults, couldn’t the same be true for those of us without diabetic mothers, too?

Some of us simply seem predisposed, if not fated, to put on weight from infancy onward. Some of us lie further along what Friedman described as the distribution of adiposity than others. In the early 1940s, the Harvard psychologist William Sheldon was referring to what he called the “morphology” of body types when he commented, “It does not take a science to tell that no two human beings are identically alike.” According to Sheldon, every human body could be described by some combination of three basic physical types: ectomorphs, who tend to be long and lean; mesomorphs, who are broad and muscular; and endomorphs, who are round and fat. You could starve endomorphs, Sheldon said, and they might lose weight and even appear emaciated, “but they do not change into mesomorphs or ectomorphs any more than a starved mastiff will change into a spaniel or a collie. They become simply emaciated endormorphs.”

In 1977, when McGovern’s committee held a hearing on obesity, Oklahoma Senator Henry Bellmon captured this dilemma perfectly. The committee had spent the day listening to leading authorities discuss the cause and prevention of obesity, and the experience had left Bellmon confused. “I want to be sure we don’t oversimplify…,” Bellmon said. “We make it sound like there is no problem for those of us who are overweight except to push back from the table sooner. But I watched Senator [Robert] Dole in the Senate dining room, a double dip of ice cream, a piece of blueberry pie, meat and potatoes, yet he stays as lean as a west Kansas coyote. Some of the rest of us who live on lettuce, cottage cheese and Ry-Krisp don’t do nearly as well. Is there a difference in individuals as to how they utilize fuel?” The assembled experts acknowledged that they “constantly hear anecdotes of this type,” but said the research was ambiguous. In fact, the evidence was clear, but it was difficult to reconcile with the assembled experts’ preconceived notion—the dogma—that obesity is caused by gluttony and/or sloth.