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.
On these high-fat, high-protein diets, according to Ohlson, her subjects appeared to add muscle or lean-tissue mass, rather than losing it, which she believed to happen inevitably with both balanced semi-starvation diets and low-protein diets. On Ohlson’s version of Pennington’s diet, her subjects stored nitrogen while losing one to three pounds of weight a week. This “can only mean that replenishment of the lean muscle mass is taking place,” Ohlson said, an observation reinforced in some of her subjects by “a reduction in dress size [that] appeared to be greater than seemed reasonable on the basis of pounds lost.”
Meanwhile, Charlotte Young at Cornell first tested Ohlson’s version of Pennington’s diet on sixteen overweight women, who lost between nine and twenty-six pounds in ten weeks, averaging nearly two pounds per week. They were “unanimous in saying that they had not been hungry,” Young wrote. She reported that her subjects seemed unexpectedly healthy while on the diets, “despite an unusually heavy siege of colds and ‘flu’ on the campus,” and that several “reported that their skins had never looked better than during the reducing regimen.” “No excessive fatigue was evident; there was a sense of well-being unusual during weight reduction.” In 1957, Young published the results of a second trial with eight overweight male students, and the results were comparable. Young fed these men an eighteen-hundred-calorie version of Ohlson’s diet. After nine weeks, the men had lost between thirteen and twenty-eight pounds, averaging almost three pounds each week. Their weight loss, Young said, “in every case” actually exceeded that expected purely from the reduction in calories. Ohlson’s and Young’s journal articles were ignored.
As with virtually all weight-loss diet studies until the last decade, these were not the kind of randomized, well- controlled trials necessary to establish whether a particular diet actually extends life or prevents chronic disease. Subjects were not randomly selected to follow a low-carbohydrate diet, or a low-calorie diet, or no diet at all, and then followed for months or years to compare the treatments and their respective risks and benefits. Rather, the logic behind them was that obese patients were themselves the controls because they had tried calorie-restricted diets and they hadn’t been successful.
For an obese person, it’s a reasonable assumption that they have tried to weigh less by eating less—i.e., calorie restriction. If that approach had worked, as Hilde Bruch noted, that person would not be obese. When Bruch described a fifty-pound weight loss in a young patient eating Pennington’s diet, she also reported that the woman had described her life, as Bruch’s obese patients often did, as a constant, ongoing failure to control her appetite and restrict her calories to a level that would maintain or reduce her weight.
In 1961, William Leith of McGill University reported his clinical experience with forty-eight patients on Pennington’s diet all of whom had previously tried low-calorie diets “without measurable success.” Half had used appetite-suppressant drugs (“anorectic agents,” as Leith called them), seven had taken “bulk substitutes,” and “eight had participated in group psychotherapy for a period of eight months,” and yet “none of them showed a sustained loss of weight.” Twenty-eight, by contrast, lost a significant portion of their excess weight on Pennington’s diet—between ten and forty pounds, averaging one and a half pounds each week. “Our results do show that satisfactory weight loss may be accomplished by a full caloric, low carbohydrate diet,” Leith concluded. “The patients ingested protein and fat as desired.” For the successful dieters, a significant success had followed a lifetime of failure.
Neither the individuals who wish to lose weight nor the clinicians who prescribe the diet need a randomized trial to tell them if it works. Such a trial is necessary only to establish that the diet works better than some other diet, and whether it leads to sustained benefits in health and longevity.
Until recently, few nutritionists or clinicians considered it worth their time and effort to test weight-reducing diets. Instead, they spent their careers studying the physiological and psychological abnormalities associated with the condition of obesity, comparing food consumption and physical activity in obese and lean individuals, and studying obesity in animals. They tried to induce fat people to endure semi-starvation by behavioral modification; they studied pharmacological methods of suppressing hunger, or surgical methods of reducing the amount of food that could be consumed or digested.*101 Testing diets or even treating obese patients was regarded as lesser work. “To be honest, obesity treatment is extremely boring,” said Per Bjorntorp, who was among the most prominent European authorities on obesity in the 1970s and 1980s. “It’s very difficult and unrewarding.” When obese individuals came to his biochemistry laboratory at the University of Goteborg, they were referred to the local nutritionists to be taught how to count and restrict calories. Since everyone knew that obesity was caused by overeating, why bother with diet trials? “There’s no point wasting your time on them,” George Bray, considered one of the world’s leading authorities, said in a recent interview. “If you get restriction of energy you will lose weight, unequivocally. It’s not an issue.”
When clinical investigators did test the efficacy of high-fat, carbohydrate-restricted diets, however, the results were remarkably consistent. Every investigator reported weight losses of between one and five pounds a week even when the investigators running the trial seemed more concerned with establishing that the diets caused deleterious side effects. Every investigator who discussed the subjective experiences of the test subjects reported that they suffered none of the symptoms of semi-starvation or food deprivation—“excessive fatigue, irritability, mental depression and extreme hunger,” as Margaret Ohlson described them.
The last of these symptoms may be the most telling. The diets induced significant weight loss without hunger even when the patients ate only a few hundred calories a day, as Russell Wilder’s did at the Mayo Clinic in the early 1930s, or 650–800 calories per day, as was the case with the patients treated by George Blackburn and Bruce
