The study included 439 overweight, postmenopausal women who were not physically active. They were randomly assigned to a weight-loss diet and/or moderate-to-vigorous aerobic exercise for 45 minutes a day, five days a week. For comparison, other women didn't change their diets or exercise habits.
At the beginning of the study, nearly 1 in 5 of the women reported they had lost at least 20 pounds three times, classifying them as "severe weight cyclers." A quarter of the women said they’d lost at least 10 pounds three times, making them moderate weight cyclers.
Overall, the women with a history of yo-yo dieting were heavier and had less favorable metabolic and hormonal profiles than the other women. Those differences stemmed from their higher BMI, larger waistlines, and greater percentage of body fat, not weight cycling itself.
By the end of the study, the women with a history of weight cycling had fared at least as well as the other women, in terms of weight loss and improvements in their metabolic and hormonal profiles.
But did the women with a history of weight cycling keep the pounds off, or was it a case of what goes down must come up? The researchers are checking on that.
“We have been able to follow many of the women out to a couple of years,” says researcher Anne McTiernan, MD, PhD, a member of the Fred Hutchinson Cancer Center’s Public Health Sciences Division. “We’re analyzing results from that follow-up now.”