Over the course of four decades, as Donaldson told it, he treated seventeen thousand patients for their weight problems. Most of them lost two to three pounds a week on his diet, without experiencing hunger. Donaldson claimed that the only patients who didn’t lose weight on the diet were those who cheated, a common assumption that physicians also make about calorie-restricted diets. These patients had a “bread addiction,” Donaldson wrote, in that they could no more tolerate living without their starches, flour, and sugar than could a smoker without cigarettes. As a result, he spent considerable effort trying to persuade his patients to break their habit. “Remember that grapefruit and all other raw fruit is starch. You can’t have any,” he would tell them. “No breadstuff means any kind of bread…. They must go out of your life, now and forever.” (His advice to diabetics was equally frank: “You are out of your mind when you take insulin in order to eat Danish pastry.”)

Had Donaldson published details of his diet and its efficacy through the 1920s and 1930s, as Frank Evans did about his very low-calorie diet, he might have convinced mainstream investigators at least to consider the possibility that it is the quality of the nutrients in a diet and not the quantity of calories that causes obesity. As it is, he discussed his approach only at in-house conferences at New York Hospital. Among those who heard of his treatment, however, was Alfred Pennington, a local internist who tried the diet himself in 1944—and then began prescribing it to his patients.

After the war, Pennington worked for the industrial-medicine division of E. I. du Pont de Nemours & Company, and specifically for George Gehrmann, the company’s medical director and a pioneer in the field of occupational health.*97 Gehrmann founded and was the first president, from 1946 to 1949, of the American Academy of Occupational Medicine, an organization that has since merged and evolved into the American College of Occupational and Environmental Medicine. By 1948, according to Gehrmann, DuPont as a corporation had become anxious about the apparent epidemic of heart disease in America. Just as Ancel Keys said he was prompted to pursue dietary means to prevent heart disease after perusing the obituaries, Gehrmann said he was prompted by the heart attack of a DuPont executive. Gehrmann decided to attack overweight and obesity, hoping heart-disease risk would diminish as a result.

“We had urged our overweight employees to cut down on the size of the portions they ate,” Gehrmann said, “to count their calories, to limit the amounts of fats and carbohydrates in their meals, to get more exercise. None of those things had worked.” These failures led Gehrmann and Pennington to test Donaldson’s meat diet on overweight DuPont executives.