Ohlson began her research by testing Pennington’s diet on members of her own laboratory. “The edibility of the food mixture, the feeling of well-being of the subjects and the ease with which meal pattern could be fitted into a daily schedule involving business and social engagements, suggested a further trial with patients,” Ohlson reported. She then prepared a version of Pennington’s diet that restricted both carbohydrates and calories, on the mistaken assumption that the diet must work by restricting calories. This was the diet that Young would also use at Cornell. It allowed only fourteen to fifteen hundred calories a day, out of which 24 percent was protein, 54 percent was fat, and 22 percent was carbohydrates.*100 Because the diet was also calorie-restricted, it did not actually test Pennington’s observation that weight would be lost even without such a calorie limitation. Nor did Ohlson or Young address the question of why their subjects never reported feeling hungry even though it provided no more calories than a typical semi-starvation diet. Still, their observations are relevant, particularly because they came in an era when high-fat diets were not yet widely considered deadly, so that researchers were not biased by this perception.

Ohlson initially tested a twelve-hundred-calorie low-fat diet on four overweight young women. This was eight hundred to a thousand calories less than these women normally ate to maintain their weight, Ohlson reported, so they should have lost at least twenty-two pounds each over the fifteen weeks of the trial. Rather, the four women lost zero, six, seven, and seventeen pounds. The “subjects reported lack of ‘pep’ throughout…[and] they were discouraged because they were always conscious of being hungry.”

Ohlson then tested her calorie-restricted version of Pennington’s diet on seven women who ranged from mildly overweight to obese. These women followed the diet for sixteen weeks and lost between nineteen and thirty-seven pounds. In a comparison of the low-fat diet of twelve hundred calories with the carbohydrate-restricted diet of fourteen to fifteen hundred calories, the former resulted in an average weight loss of a half-pound a week, whereas the latter diet, higher in calories, induced an average weight loss of almost three pounds weekly. “Without exception, the low-carbohydrate reducing diet resulted in satisfactory weight losses,” Ohlson wrote. “The subjects reported a feeling of well-being and satisfaction. Hunger between meals was not a problem.”

Over a ten-year period, Ohlson’s laboratory tested a range of dietary compositions on nearly 150 women, including between 50 and 60 women on her version of Pennington’s diet. She also tested low-protein diets and diets low in fat (only 180 calories, or less than 15 percent fat) but high in carbohydrates. Her subjects considered these low-fat diets to be “dry, uninteresting, [and] hard to eat,” no more satisfying than those regimens of turnips, bread, and cabbage that Ancel Keys had fed his conscientious objectors. Diets with 360 calories of fat proved “sufficient to provide acceptability,” she added, but her subjects “uniformly” preferred the high-fat diets, with seven to eight hundred calories of fat. At that level, the women “did not appear to give as much thought to forbidden foods,” and “they also appeared to be more successful in controlling appetite during college vacations.” Simply put, Ohlson’s subjects were not as hungry on the high-fat, low-carbohydrate diet as they were on the low-fat, high-carbohydrate regimens.