Over one-third of Americans are obese, according to a recent report issued by the Centers for Disease Control and Prevention (CDC). It is no surprise, then, that the weight-loss industry is a multi-billion dollar industry, as many people struggle to maintain weight loss after diets. For many people, they find that their attempts to lose weight backfire as, once they stop dieting, they regain the weight.

Researchers had previously reported that yo-yo dieting affected people's metabolism but a recent study conducted by researchers in Seattle, Chicago, Vancouver, Bethesda, Maryland, Boston and Germany has cast doubt on that theory. The new findings indicate that women who'd had a history with yo-yo dieting did not suffer from slower metabolism and an inability to lose weight as compared to their peers.

Caitlin Mason, from the Fred Hutchinson Cancer Research Center, and her colleagues conducted a study with 439 women. All were overweight or obese, postmenopausal (aged, in this trial, between 50 and 75), inactive, and 42 percent of the women had had a history of yo-yo dieting, which was defined as the loss of the same 10 pounds at least three times.

Of the women, 77 had a history of severe "weight cycling," which was defined as the loss of 20 pounds at least three times. The women were separated into four groups, with the goal of losing 10 percent of their original body weight. The first dieted only, the second dieted and exercised, the third exercised, and the fourth had no intervention. The trial occurred over the course of a year.

While the women who had been yo-yo dieters weighed more than their peers before the start of the study, investigators found that they adhered just as well to the methods assigned to them. The women who only dieted lost an average of 16 pounds, while the women who dieted and exercised lost an average of 20 pounds. Researchers found that the women with a history of yo-yo dieting lost the same amount of weight as their counterparts and, in fact, when using just exercise to lose weight, lost even more.

The study, published in the journal Metabolism, highlights two things: that it is never too late to start the trek back to a healthy weight, and that healthy weight maintenance cannot occur with a diet but with a change in lifestyle. As Anne McTiernan, the study's senior author said to USA Today, diets do work if you use a structure and stick with it.

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