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Surprising Endorsement of Yo-Yo Dieting

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The weight cycling industry has cause for celebration this week. A study was published in Metabolism titled "History of weight cycling does not impede future weight loss or metabolic improvements in postmenopausal women." The purpose of the study, in the authors' own words, was:

Given that the repetitive loss and regain of body weight, termed weight cycling, is a prevalent phenomenon that has been associated with negative physiological and psychological outcomes, the purpose of this study was to investigate weight change and physiological outcomes in women with a lifetime history of weight cycling enrolled in a 12-month diet and/or exercise intervention.

They enrolled 439 overweight, inactive, postmenopausal women in the study. Of those, 103 were "moderate weight cyclers" (yo-yo dieters who had lost 10 or more pounds three or more times) and 77 were "severe weight cyclers (yo-yo dieters who had lost 20 or more pounds three or more times). They found that moderate and severe weight cyclers were heavier and had less favorable metabolic profiles than non-cyclers at baseline.

If the study had stopped right there (as it should have), the rational conclusion would have been, "A history of weight cycling was present in 41 percent of overweight, inactive postmenopausal women seeking weight loss. Weight cycling was associated with higher weight and less favorable metabolic profiles. Alternatives to traditional weight loss interventions should be sought."

Instead, blinded by an old paradigm that weight loss should be pursued at any cost, the research team found it advisable to place these women with known weight cycling, higher weights, and less favorable metabolic profiles, on yet another round of diet and exercise intervention. What is that popular definition of insanity? Oh yeah. Doing the same thing over and over and expecting different results.

Nonetheless, that is exactly what they did. The participants were randomized to one of four groups: diet, exercise, diet and exercise, or a control group. The diet intervention consisted of 1,200-2,000 calories (based on starting weight), a weekly group meeting for six months, and at least two visits with the study dietitian, followed by monthly groups for six additional months and email and phone follow-up with study dietitians. The women were asked to record all food eaten daily for at least six months and their journals were collected and returned with feedback.

The exercise intervention progressed to 45 minutes of moderate- to vigorous-intensity exercise five days per week. Three sessions per week took place at the study facility and two sessions at home. Participants recorded the type and duration of exercise, peak heart rate, and perceived exertion.

Both weight cyclers and non-weight cyclers lost 9-11 percent of their body weight with a year of supervised diet and/or exercise. There was no difference in adherence to the plan between those with a history of weight cycling and non-weight cyclers. (This disproves the commonly held perception that yoyo dieters lack willpower.) Except for one subgroup, the metabolic improvements were similar.

So why did the fact that yo-yo dieters lost weight make headlines? They had already proven they could lose weight at least three times before! The issue is keeping it off. Although we don't yet know what will happen to the dieters in this study after one year, a review of studies of the long-term outcomes of calorie-restricting diets concluded that "there is little support for the notion that diets lead to lasting weight loss or health benefits." Therefore, all of the dieters in this study have a high likelihood of weight cycling as a result of this intervention. Perhaps even a few of the non-cyclers have been started down the path of yoyo dieting.

In addition, this study did not assess the psychological effects of the intervention or the amount of time and energy required to log all of their food and exercise. In my work with yo-yo dieters over the last 13 years, I can tell you that the toll it takes is substantial. Previous research has shown, as summarized by this study's authors, that, "repetitive weight loss followed by regain has been associated with unfavorable physiological and psychological outcomes including effects on body composition, metabolic rate, immune function, and lower body esteem." Therefore, is it prudent to recommend another round of dieting for weight-cyclers based on a one-year study?

So why did they? Presumably, the rationalization is that these women should try dieting again because of their higher weights and less favorable metabolic profiles. This ignores another possible conclusion: Because of their dieting, they have higher weights and less favorable metabolic profiles.

I am all for healthier eating and increased physical activity, but billions of dollars are spent each year on treatments that obviously don't work long-term. What other intervention would health care professionals routinely prescribe knowing that there is a high likelihood of failure -- or even worsening of their condition -- and then blame the patient? And why are they still investigating the effects of yo-yo dieting instead of non-restrictive approaches to eating and physical activity that are positive and sustainable?

Yes, the weight cycling industry is thriving on this insanity.

For more by Michelle May, M.D., click here.

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