According to a new study, yo-yo dieting does not have a negative impact on metabolism or the ability to lose weight in the long term.

The study, conducted by researchers at Fred Hutchinson Cancer Research Center, is published online in the journal Metabolism.

Anne McTiernan, M.D., Ph.D., a member of the Hutchinson Center’s Public Health Sciences Division, explained: “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.”

At present, around two-thirds of people in the United States are overweight or obese, and around 50% of women in the country are currently trying to lose weight. Obesity is a known risk factor for cardiovascular disease and diabetes and also for many types of cancer. It is believed that the association between body fat and the production of certain hormones and inflammatory markers contribute to the increase risk of developing cancer.

McTiernan said:

“We know there’s an association between obesity, sedentary behavior and increased risk of certain cancers. 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.”

For the study the team examined data from 439 women in the Seattle area, who were either overweight or obese and led sedentary lifestyles. The participants, aged 50-75, were randomly assigned to 1 of 4 groups:

  • reduced-calorie diet only
  • exercise only (primarily brisk walking)
  • reduced-calorie diet in addition to exercise
  • control group with no intervention

According to the researchers, at the end of the one year study, those assigned to either the diet-only and diet-plus exercise groups lose an average of 10% of their starting weight.

The researchers set out to determine if women with a moderate or severe weight cycling found it hard to lose weight than women who had never yo-yo dieted.

According to the researchers:

  • 18% of women met the criteria of severe weight cycling
  • 24% met the criteria of moderate weight cycling

Women who met criteria for severe weight cycling lost 20+ pounds on three or more occasions, while those who met the criteria for moderate weight cycling lost 10+ pounds on three or more occasions.

At the end of the study, the team found no significant differences between severe weight cyclers and those who didn’t with regard to the ability to successfully take part in diet and/or exercise programs.

Furthermore, the team found no differences between cyclers and non-cyclers regarding the affect of diet or diet-plus-exercise on weight loss, percentage of body fat and lean muscle mass gained or lost.

There was also no significant differences among cyclers and non-cyclers in other physiological factors, such as blood pressure, insulin sensitivity, blood concentrations of hormones, such as leptin, and adiponectin.

The researchers explained: “To our knowledge, no previous studies have examined the effect of prior weight cycling on the body composition, metabolic and hormonal changes induced by a comprehensive lifestyle intervention in free-living women.”

The National Institutes of Health, the National Cancer Institute and the Canadian Institutes of Health funded the research. The study also included investigators at Harvard Medical School, the National Cancer Institute and the University of Washington.

Written by Grace Rattue