SEATTLE — "Yo-yo dieting" — the repetitive loss and regain of body weight — does not negatively affect metabolism or the ability to lose weight long term, researchers at Fred Hutchinson Cancer Research Center reported in a new study published in the journal Metabolism.
“A history of unsuccessful weight loss should not dissuade an individual from future attempts to shed pounds or diminish the role of a healthy diet and regular physical activity in successful weight management,” stated the study’s senior author Anne McTiernan, a member of the Hutchinson Center’s Public Health Sciences Division. “We know there’s an association between obesity, sedentary behavior and increased risk of certain cancers,” McTiernan said. “The World Health Organization estimates that a quarter to a third of cancers could be prevented with maintenance of normal weight and keeping a physically active lifestyle."
The study was based on data from 439 overweight-to-obese, sedentary Seattle-area women, ages 50 to 75 years, who were randomly assigned to one of four groups: reduced-calorie diet only, exercise only (mainly brisk walking), reduced-calorie diet plus exercise and a control group that received no intervention. At the end of the yearlong study, participants on the diet-only and diet-plus-exercise arms lost an average of 10% of their starting weight, which was the goal of the intervention.
The analysis aimed to determine whether women with a history of moderate or severe weight cycling were at a disadvantage compared with nonweight-cyclers when it came to losing weight. Of the study participants overall, 18% met the criteria for severe weight cycling (having reported losing 20 or more pounds on three or more occasions) and 24% met the criteria for moderate weight cycling (having reported losing 10 or more pounds on three or more occasions).
Although severe weight cyclers were, on average, nearly 20 pounds heavier than noncyclers at the start of the study, at the end of the study, 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. The cyclers also did not differ from the noncyclers with regard to the impact of diet or diet-plus-exercise on weight loss, percentage of body fat and lean muscle mass gained or lost. Other physiological factors, such as blood pressure, insulin sensitivity and blood concentrations of such hormones as leptin (which helps make one feel full) and adiponectin (which helps regulate glucose levels) also did not differ significantly among those whose weight fluctuated and those whose did not.