By perceiving obesity as an eating disorder, a defect of behavior rather than physiology, and by perceiving excessive hunger as the cause of obesity, rather than a symptom that accompanies the drive to gain weight, those investigators concerned with human obesity had managed to dissociate the perception of hunger and satiety from any underlying metabolic conditions. They rarely considered the possibility that hunger, satiety, and level of physical activity might be symptomatic of underlying physiological conditions. Imagine if diabetologists had perceived the ravenous hunger that accompanies uncontrolled diabetes as a behavioral disorder, to be treated by years of psychotherapy or behavioral modification rather than injections of insulin. These researchers simply never confronted the possibility that the nutrient composition of the diet might have a fundamental effect on eating behavior and energy expenditure, and thus on the long-term regulation of weight.

There is one way to test this latter notion, and, in fact, such tests were done from the 1930s onward. Alter the proportion of fats and carbohydrates in experimental diets and see what happens. Test low-fat diets versus low-carbohydrate diets, keeping in mind that a diet low in fat must be high in carbohydrates and vice versa. This would test the notion that these nutrients have unique metabolic and hormonal effects that influence weight, hunger or satiety, and energy expenditure. Such trials provide the means of answering these fundamental questions: What happens when we eat a diet restricted in carbohydrates, but not calories? Do we lose or gain weight? Are we as hungry as we are when calories are restricted? Do we eat more or less? Do we expend more or less energy? And what about when fat is restricted, but carbohydrates or calories are not? What are the effects on hunger, energy expenditure, and weight?

Chapter 19

Chapter Nineteen

REDUCING DIETS

Concentrated carbohydrates, such as sugars and breadstuffs, and fats must be restricted. Diets, therefore, should exclude or minimize the use of rice, bread, potato, macaroni, pies, cakes, sweet desserts, free sugar, candy, cream, etc. They should consist of moderate amounts of meat, fish, fowl, eggs, cheese, coarse grains and skimmed milk.

ROBERT MELCHIONNA of Cornell University, describing the reducing diet prescribed at New York Hospital in the early 1950s