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.

In June 1949, Pennington published an account of the DuPont experience in the journal Industrial Medicine. He had prescribed Donaldson’s regimen to twenty executives, and they lost between nine and fifty-four pounds, averaging nearly two pounds a week. “Notable was a lack of hunger between meals,” Pennington wrote, “increased physical energy and sense of well being.” All of this seemed paradoxical: the DuPont executives lost weight on a diet that did not restrict calories. The subjects ate a minimum of twenty-four hundred calories every day, according to Pennington: eighteen ounces of lean meat and six ounces of fat divided over three meals. They averaged over three thousand calories. Carbohydrates were restricted in their diet—no more than eighty calories at each meal. “In a few cases,” Pennington reported, “even this much carbohydrate prevented weight loss, though an ad-libitum [unrestricted] intake of protein and fat, more exclusively, was successful.”*98