Study: Dieting does not work, researchers report
amy April 5th, 2007
Here’s some more evidence against dieting. UCLA researchers have analyzed 31 long term diet studies and will publish their results in the April issue of American Psychologist. The researchers have concluded not only that diets are not an effective way to lose weight for the long term, but that in many cases dieting can actually be worse for you than maintaining your current weight:
“What happens to people on diets in the long run?” Mann asked. “Would they have been better off to not go on a diet at all? We decided to dig up and analyze every study that followed people on diets for two to five years. We concluded most of them 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.”
People on diets typically lose 5 to 10 percent of their starting weight in the first six months, the researchers found. However, at least one-third to two-thirds of people on diets regain more weight than they lost within four or five years, and the true number may well be significantly higher, they said.
In some cases, the dieters ended up gaining more weight in the long run than those who did not try to diet:
“Several studies indicate that dieting is actually a consistent predictor of future weight gain,” said Janet Tomiyama, a UCLA graduate student of psychology and co-author of the study. 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.
One interesting thing that the researchers mention is the negative effects yo-yo dieting can have on your body. I remember seeing an article on MSNBC years ago that said that yo-yo dieting was actually better for your heart than staying overweight, since your body still benefited from those times that you were at a lower weight. I haven’t heard much about the health of yo-yo dieting since, though, either because I totally missed it or it is not talked about at great length. I suspect it’s at least partly the latter, since it is not in the weight loss industry’s interest to scare us off from trying the same diets that have failed us in the past over and over again. This article suggest that yo-yo dieting has a negative effect, and other articles I found seem to agree.
Evidence suggests that repeatedly losing and gaining weight is linked to cardiovascular disease, stroke, diabetes and altered immune function. Mann and Tomiyama recommend that more research be conducted on the health effects of losing and gaining weight, noting that scientists do not fully understand how such weight cycling leads to adverse health effects.
The article is not all grim for those who wish to shed pounds, however, as it gives a slight nod to the importance of healthy eating and exercise, without dieting:
“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.”
Here are some additional thoughts on the article:
- I assume that the studies the article assessed were looking at specific diets (e.g. Weight Watchers, Atking, Jenny Craig, etc.), so it’s bad news for dieters but not necessarily those trying to lose weight through other methods (such as myself).
- Unfortunately the article doesn’t go into a lot of detail (what diets were studies, how overweight the patients were, etc.), so it’s a bit difficult to assess the validity of the research without reading the actual study (which I wasn’t able to find). Some of the conclusions could be a bit suspect depending on the individuals who were studied.
- Were the non-dieters who gained less weight just as overweight or obese as the dieters? Maybe that could explain why they did not try to diet in the first place or gained less weight later due to better eating habits.
- How much weight did the people in the studies lose? If they lost a significant amount of weight, it seems like it would take longer for them to gain it back if they were making at least some attempt to continue to eat healthy.
You can find the full article here.
