In a new study, researchers found repeatedly losing and regaining weight may lead to improved insulin levels and lower body fat percentages in the long term, even during the weight regain phases.
The research was conducted by a team from the University of Washington.
Many people with obesity in the U.S. fall into the pattern of losing and regaining the weight.
Some studies suggest that this pattern, called “weight cycling” or “yo-yo dieting,” has been associated with health risks such as high blood pressure and high cholesterol.
However, little is known about hormone regulation and body fat composition after multiple episodes of weight cycling.
In the study, the team examined rats that were exposed to four cycles of calorie-restricted weight loss followed by weight regain through unlimited access to food (“weight cyclers”) over the course of a year.
The weight cyclers were compared with a control group that had unlimited access to food for the full trial period.
By the end of the year-long trial, the control group had gained a big amount of weight.
During each regain period, the weight cycler group added more weight than had they lost.
However, by the third cycle of weight loss and regain, the group weighed far less than their control counterparts.
After the first cycle, when compared with the controls, the weight cyclers ate less during the weight regain periods and had lower body fat mass and insulin levels.
In addition, there was no difference in levels of leptin and ghrelin—hormones that control hunger, appetite, and weight regulation—between the two groups.
This suggests the stability of hormone levels even throughout periods of weight cycling.
The team says the improvement in fat mass, as well as improvement in glucose tolerance in weight cycling, implies metabolic benefits to the periods of caloric restriction, despite the stress of the weight gain times.
Future research should focus on the health implications of weight cycling, including whether there is a beneficial impact on metabolic syndrome.
If the findings do apply to humans, then patients and clinicians can take heart that it may be better to try [to lose weight] and eventually regain weight after weight loss by calorie restriction, even repeatedly, than not to try at all.
The study is published in the American Journal of Physiology—Endocrinology and Metabolism.
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