Appearing in the April issue of American Psychologist, a review of past diet studies has found that at best, diets are ineffective and at worst, a serious health risk.
Diets do not lead to sustained weight loss or health benefits for the majority of people, said review author Traci Mann. "You can initially lose 5 to 10 percent of your weight on any number of diets, but then the weight comes back. Sustained weight loss was found only in a small minority of participants, while complete weight regain was found in the majority. Diets do not lead to sustained weight loss or health benefits for the majority of people."
The review noted that certain factors biased the diet studies to make them appear more effective than they really were. For example, many participants self-reported their weight by phone or mail rather than having their weight measured on a scale by an impartial source. Also, the studies have very low follow-up rates, and those who responded may not have been representative of the entire group, since people who gain back large amounts of weight are generally unlikely to show up for follow-up tests.
"Several studies indicate that dieting is actually a consistent predictor of future weight gain," said co-author Janet Tomiyama. One study found that both men and women who participated in formal weight-loss programs gained significantly more weight over a two-year period than those who had not participated in a weight-loss program, she said.
The review concluded that most dieters would have been better off not going on the diet at all. "Their weight would be pretty much the same, and their bodies would not suffer the wear and tear from losing weight and gaining it all back," explained Mann, noting that evidence suggests that repeatedly losing and gaining weight is linked to cardiovascular disease, stroke and altered immune function.
So, if dieting doesn't work, what does? "Eating in moderation is a good idea for everybody, and so is regular exercise," Mann said. "That is not what we looked at in this study. Exercise may well be the key factor leading to sustained weight loss. Studies consistently find that people who reported the most exercise also had the most weight loss. Diets [alone] are not effective in treating obesity. We are recommending that Medicare should not fund weight-loss programs as a treatment for obesity. The benefits of dieting are too small and the potential harm is too large for dieting to be recommended as a safe, effective treatment for obesity."
BMI: A Big Fat Lie?
Accept Your Body And Ditch The Dieting!
Body Image And Sex
Source: University of California - Los Angeles