Yo-yo dieting doesn't hurt metabolism

A history of yo-yo dieting does not negatively affect metabolism or the ability to lose weight in the long term, U.S. researchers say. Senior author Dr. Anne McTiernan of Fred Hutchinson Cancer Research Center in Seattle, said the affect of yo-yo dieting -- the repetitive loss and regain of body weight, also called weight cycling -- on the metabolism or a person's ability to lose weight in the long run has been unclear. The researchers analyzed data from 439 overweight-to-obese, sedentary Seattle-area women, ages 50-75, who were randomly assigned to one of four groups: reduced-calorie diet only, exercise only, reduced-calorie diet plus exercise and a control group that received no intervention. At the end of the yearlong study, those on the diet-only and diet-plus-exercise arms lost an average of 10 percent of their starting weight -- the goal of the intervention. The study, published in the journal Metabolism, found although severe weight cyclers were, on average, nearly 20 pounds heavier than non-cyclers at the start of the study, at the end the researchers found no significant differences between those who yo-yo dieted and those who didn't with regard to the ability to successfully participate in diet and/or exercise programs.