In an argument on an earlier thread, Don asks:
It’ll take me two posts to answer Don’s question. In this post – which can be skipped by those of you who hate reading big blocks of quotes – I want to point out that some experts writing in the peer-reviewed scientific literature strongly doubt that fat people can choose to be thin.
In Don’s view, as I understand it, body weight is a function of two variables – the intake of calories (eating) and the expenditure of energy (exercise). If fat people only ate less and walked more, they’d cease being fat people; therefore, being fat is a choice.
But it’s not universally true that fat people have bad diets and bad exercise habits. Some fat people are healthy eaters who exercise often; most fat people have diets and lifestyles that are less than ideal, but not significantly different from that of most non-fat Americans.
In fact, although it’s commonly believed that fat people must eat a lot more than thin people, the scientific evidence for that is either non-existant or non-replicable. Multiple studies, based both on observation and on diaries, have found that fat and thin people eat similar amounts. From an article in Clinical Psychology Review (citations omitted):
[In a study of children], Rolland-Cachera and Bellisle found that food intake was about 500 calories greater and obesity about four times more common in the lowest versus the highest socioeconomic groups studied; however, within each socioeconomic group, there were comparable levels of caloric intake among lean, average weight, and obese children. [...]
…It may be concluded that nature and nurture both exert influences on body weight and that the eventual expression of obesity is a complicated matter…. Regardless of these factors, the myth of overeating by the obese is sustained for the casual observer by selective attention. Each time that a fat person is observed to have a “healthy appetite” or an affinity for sweets or other high calorie foods, a stereotypic leap into causality is made. The same behaviors in a thin person attract little or no attention….
…The major premise of dietary treatments of obesity, that the obese overeat with respect to population norms, must be regarded as unproven.
Since the premise behind diets is unproven, it should be no surprise that diets themselves have never been proven to work over the long run. From a review of empirical tests of weight-loss plans by Wayne Miller, an exercise science specialist at George Washington University:
William Bennett, editor of the Harvard Medical School Health Letter, reviewed empirical weight-loss studies going back to the 1930s. He concluded that not one had been shown to produce long-term weight loss for more than a tiny minority of dieters (and most of the few who did lose weight, lost too little weight to turn an obese person into a non-obese person).
An important element of behavior modification is giving the client a model of his or her problem, one that focuses on eating behavior as the target for correction. An essential component of this model is the claim that it will be effective if the client believes it and acts accordingly. The model that appears to form the heart of most such programs, however, is at the very least seriously incomplete; there is good reason to assume it is simply wrong. In any case, the model has not produced results that would support claims of effectiveness. …
The ethical questions that can be raised about research efforts also must be asked about the dietary programs for weight control that are carried on outside a research setting – commercial, hospital, or clinic-based, or self-help. Many such programs proffer treatment as though it were established as effective and safe. Nothing in the results published by research programs authorizes anyone to make such claims.
From an article in The New England Journal of Medicine:
Why is it that people cannot seem to lose weight, despite the social pressures, the urging of their doctors, and the investment of staggering amounts of time, energy, and money? The old view that body weight is a function of only two variables – the intake of calories and the expenditure of energy – has given way to a much more complex formulation involving a fairly stable set point for a person’s weight that is resistant over short periods to either gain or loss, but that may move with age. …Of course, the set point can be overridden and large losses can be induced by severe caloric restriction in conjunction with vigorous, sustained exercise, but when these extreme measures are discontinued, body weight generally returns to its preexisting level.
In my next post, I’ll return to Don’s question.
- David Garner and Susan Wooley, “Confronting The failure of Behavioral and Dietary Treatments for Obesity,” Clinical Psychology Review, v11 p729-780, 1991.
- Wayne C. Miller, “How effective are traditional dietary and exercise interventions for weight loss?,” Medicine and Science in Sports and Exercise, 31 no8 1129-34 Aug 1999
- Jerome Kassierer and Marcia Angell, “Losing Weight – An Ill-Fated New Year’s Resolution,” New England Journal of Medicine, vol 338(1), p52-54, Jan 1 1998.
- William Bennett, “Dietary Treatments of Obestity,” Annals of the New York Academy of the Sciences, v499, p250-263, 1987.