Is it me, or does it seem like every week some new diet claims to be able to ameliorate the burden of losing weight? Some diets cite a research tested physiological mechanism by which the fat will just “melt away”. Others try and convince you that dieting can be fun like the recent “Hollywood Cookie” diet. But, by and large, all diets work the same way- they are programs of eating designed to limit your caloric intake. Diets are difficult to keep up. Not only does their logic fly in the face of some of our most basic instincts (i.e., to eat when you are hungry) but it also makes the foods that we try to stay away from all the more tempting. Are diets really worth all of that effort and sacrifice? UCLA researchers say that they probably aren’t.

Traci Mann, PhD, A. Janet Tomiyama, M.A., and their colleagues recently published an exhaustive review of studies that evaluated the long-term efficacy of diets- “a severe restriction of calorie intake”- and their long-term health benefits. They found that diets generally only yield short-term weight-loss in the first six months (Mann, Tomiyama, Westling, Lew, Samuels, & Chatman, 2007). For those studies of diets that did evidence long-term weight-loss (2 years or longer), it was impossible to tell whether the lasting weight-loss was actually due to the diet or lifestyle changes that may have accompanied it, such as exercise, supplements, or medication

One particularly interesting point that these researchers underscore is that, while some diets may have positive, short-term, health benefits, dieting itself may increase our risks of cardiovascular disease, diabetes, hypertension, and mortality in general (Blair, Shaten, Brownell, Collins, & Lissner, 1993; see also Mann, et al., 2007 for review of findings). Interestingly, the long-term health risks mirror the short-term benefits. That is, diets may be effective ways to reduce risks of hypertension and diabetes in the short-run. The authors suggest that the reason why these benefits may turn into risks in the long-run may be due to the ephemeral nature of most diets. Because diets are so difficult to maintain in the long-term, dieters’ weight can vacillate in unhealthy ways. It would seem that frequent cycles of weight-gain followed by weight loss wreck havoc on our bodies!

What can we learn from this excellent research? Well, an obvious implication is that diets are not necessarily the way to a healthy lifestyle. Rather, the researchers suggest that it may be other systemic lifestyle changes that contribute most to weight-loss and a decreased risk of mortality. Chief among these, of course, is exercise (Mann, et al., 2007). I’m sure we can think of a few others though. For example, it may be better to change our outlook on food itself. Instead of rewarding ourselves with the “guilty pleasures” of food, we should try to find other sources of reward, like sports, a good movie, a hobby, or just a long walk on the beach.

Further Reading:

Mann, T. A., Tomiyama, A. J., Westling, E., Lew, A., Samuels, B, and Chatman, J. (2007). Medicare’s Search for Effective Obesity Treatments: Diets are not the answer. American Psychologist, 62, 220-233.

Anderson, J. W., Konz, E. C., Frederich, R. C., and Wood, C. L. (2001). Long-term weight-loss maintenance: A meta-analysis of US studies. American Journal of Clinical Nutrition, 74, 579-584.

Anderson, J. W., Vichitbandra, S., Qian, W., and Kryscio, R. J. (1999). Long-term weight maintenance after an intensive weight-loss program. Journal of the American College of Nutrition, 18, 620-627.

Blair, S. N., Shaten, J., Brownell, K. D., Collins, G., & Lissner, L. (1993). Body weight change, all-cause mortality, and cause-specific mortality in the Multiple Risk Factor Intervention Trial. Annals of Internal Medicine, 119, 747-757.

Fogelholm, M. and Kukkonen-Harjula, K. (2000). Does physical activity prevent weight gain—A systematic review. Obesity Reviews, 1, 95-111.

Grimm, R. H., J.r., Cohen, J. D., Smith, W. M., Falvo-Gerard, L., & Neaton, J. D. (1985). Hypertension management in the Multiple Risk Factor Intervention Trial (MRFIT): Six year intervention results for men in Special Intervention and Usual Care Groups. Archives of Internal Medicine, 145, 1191-1199.