together. It would seem there is something about carbohydrates that allows the consumption of such enormous quantities of food and yet still induces hunger as the night approaches.
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?
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
THE AMERICAN HEART ASSOCIATION TODAY insists that severe carbohydrate restriction in a weight-loss diet constitutes a “fad diet,” to be taken no more seriously than the grapefruit diet or the ice-cream diet. But this isn’t the case. After the publication of Banting’s
Those early weight-loss diets were meant to eliminate fat tissue while preserving muscle or lean-tissue mass. The protein content of the diet would be maximized and calories reduced. Only a minimal amount of carbohydrates and added fats—butter and oils—would be allowed in the diet, because these were considered the nonessential, i.e., nonprotein, elements. When physicians from the Stanford University School of Medicine described the diet they prescribed for obesity in 1943, it was effectively identical to the diet prescribed at Harvard Medical School and described in 1948, at Children’s Memorial Hospital in Chicago in 1950, and at Cornell Medical School and New York Hospital in 1952. According to the Chicago clinicians, the “general rules” of a successful reducing diet were as follows:
1. Do not use sugar, honey, syrup, jam, jelly or candy.
2. Do not use fruits canned with sugar.
3. Do not use cake, cookies, pie, puddings, ice cream or ices.
4. Do not use foods which have cornstarch or flour added such as gravy or cream sauce.
5. Do not use potatoes (sweet or Irish), macaroni, spaghetti, noodles, dried beans or peas.
6. Do not use fried foods prepared with butter, lard, oil or butter substitutes.
7. Do not use drinks such as Coca-Cola, ginger ale, pop or root beer.
8. Do not use any foods not allowed on the diet and [for other foods use] only as much as the diet allows.
With the carbohydrates and added fats minimized in these diets, meat was inevitably the primary constituent. This would provide the protein necessary to ensure that weight loss came mostly from the patient’s fat and not the muscle. The idea was to keep the body in what is called nitrogen equilibrium, with the nitrogen consumed from the protein in the diet balancing out the nitrogen being excreted in the urine from the breakdown of muscle protein.
When these clinicians discussed what plant foods they would allow in their diets, they typically did so on the basis of the carbohydrate content: potatoes are nearly 20 percent carbohydrate by weight (the rest is mostly water), so they were known as 20-percent vegetables. Green peas and artichokes are 15-percent vegetables. Onions, carrots, beets, and okra are 10-percent vegetables. Most of the green vegetables—including lettuce, cucumbers, spinach, asparagus, broccoli, and kale—are 5-percent, which means carbohydrates constitute at most 5 percent of their weight. These weight-loss diets allowed only 5-percent vegetables, which ruled out all starchy vegetables, like potatoes. Because a one-cup serving of a 5-percent vegetable will yield only twenty to thirty calories, as the University of Toronto physician Walter Campbell wrote in 1936, “the inclusion of an extra portion or omission of an undesired portion is of little moment in the [dietary] scheme as a whole.” Some of these diets did allow an ounce or two of bread—usually whole-grain, because white bread had too few vitamins to make it worth including. But most did not. “All forms of bread contain a large proportion of carbohydrate, varying from 45–65 percent,” noted H. Gardiner-Hill of London’s St Thomas’s Hospital Medical School in 1925, “and the percentage in toast may be as high as 60. It should thus be condemned.”
When these physicians talked about lean meat as the basis of a weight-reducing diet, they did not mean a chicken breast without the skin, as has been the iconic example for the past twenty years. They meant any meat, fish, or poultry (bacon, salt pork, sausage, and duck occasionally excepted) in which the visible fat had been trimmed away.
Once weight was satisfactorily lost, weight-maintenance diets were also restricted in carbohydrates, although not so drastically. For maintaining a reduced weight, as described by the Pittsburgh physician Frank Evans in the 1947 edition of the textbook
