The elusive advantages of under eating

  In the early 1990s, the National Institutes of Health set up to investigate a few crucial issues of Women’s Health Initiative (WHI), a collection of studies that would cost in the neighbourhood of a billion dollars. Among the questions that the researchers hoped to answer was even if low-fat diets actually prevent heart disease or cancer, at least in women. So they enrolled nearly 50 000 women in a trial, chose 20 000 at random, and instructed them to eat a low-fat diet, rich in fruits, vegetables, and fiber. These women were given regular counselling to motivate them to stay on the diet.

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    One of the effects of this counseling, or maybe of the diet itself, is that the women also decided, consciously or unconsciously, to eat less. According to the WHI researchers, the women, on average, consumed 360 calories a day less on their diets than they did when they first agreed to participate. If we believe that overeating causes obesity, we might say that these women were “under eating” by 360 calories a day. They were eating almost 20% fewer calories than what public-health agencies tell us such women should be eating.

     The result? After 8 years of such under eating, these women lost an average of 2 pounds each. And their average waist circumference–a measure of abdominal fat–increased. This suggests that whatever weight these women lost, if they did was not fat but lean tissue–muscle.

   This wasn’t the only disappointing result in the study. The WHI investigators also reported that the low–fat diet failed to prevent heart disease, cancer, or anything else.

    This calculation is oversimplified to make a point. If it is corrected for the observation that subjects who lose weight in diets expend less energy as they do it, then the amount of weight loss expected with this energy deficit should be less” approximately 1.6 pounds at 3 weeks and 22 pounds at 1 year. I owe this correction to Kevin Hall, a Biophysicist at NIH, who points out that the corrected numbers are “still a far cry from the observed value!”

    Although Stunkard’s analysis has widely been perceived as a condemnation of all methods of dietary treatment of obesity, the studies he reviewed included only calories-restricted diets.

   I don’t count the WHI low-fat diet trial, because that was aimed at preventing heart disease and cancer, not losing weight.

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