What Is Weight Cycling or “Yo-Yo”?

A successful weight loss is usually defined as a >10% loss of initial body weight maintained for at least one year.¹ However, most individuals regain the lost weight, with studies showing that nearly 80% of individuals who voluntarily lost weight will regain some or all of it back within a year.² The cyclical pattern of losing and regaining weight is commonly referred to as the “yo-yo dieting” or weight cycling.³

How Does Weight Cycling Affect Health?

Weight regain is commonly seen after initial weight loss usually due to decreased adherence to weight management strategies as well as physiological mechanisms that compensate for weight loss.⁴ Although weight cycling is extremely common among dieters, the effects of it have not yet been extensively studied.

Rigorous research on this topic is sparse, but some studies show that weight cycling is associated with increased risk of mortality and of developing heart disease, stroke, type 2 diabetes mellitus (T2DM), eating disorders, hypertension, and bone fractures.^3,4

However, emerging evidence suggests that weight cycling may have nuanced effects on health depending on the individual’s initial weight status.^5,6 Weight cycling may negatively affect the cardiometabolic health of individuals with normal body weight, but in individuals who are obese or overweight, the risks of weight cycling may not be greater than the risks of sustained obesity without any initial weight loss.

For instance, one cross-sectional study using the National Health and Nutrition Examination Survey data from 1999-2014 found that weight cycling was associated with significantly worsened lipid levels in individuals with normal weight who weight cycled.⁵ However, the study did not find adverse effects on lipid levels in obese or overweight individuals who weight cycled, but found only marginally worsened insulin sensitivity in this group. Researchers concluded that the risks of weight gain are greater than the risks of weight cycling for obese or overweight individuals, but that weight cycling in normal weight individuals can have clinically significant adverse effects on health. 

Other studies corroborate such findings.^6,7 For instance, when changes in cardiometabolic markers were analyzed in the Look AHEAD (Action for Health in Diabetes) trial in obese and overweight individuals with T2DM who regained weight after a weight loss intervention, no negative effects were seen.⁶ Obese and overweight individuals who regained their weight four years after the intervention did not see worsened cardiovascular disease risk factors, but had sustained improvements in hemoglobin A1c levels even if the weight was fully or partially regained. This effect was especially true for those who experienced large initial weight loss. Additionally, a recent systematic review and meta-analysis examining the effect of weight cycling and risk of developing diabetes found that weight cycling is associated with a 23% increase in the risk of diabetes.⁷ However, similar to other studies, this association was not found for individuals who were obese.

Thus current research seems to suggest that in those who are overweight or obese, weight loss is beneficial even if part of or all of the lost weight is regained, highlighting the detrimental health effects of sustained obesity.^5–7 More research is needed to explain the mechanism behind the harmful effects of weight cycling in individuals with healthy weight, but researchers currently hypothesize that weight cycling promotes loss of lean muscle mass during weight-loss periods without regaining of muscle mass during weight-gain periods, while also promoting visceral fat accumulation.^4,5 This may cumulatively have negative effects on overall cardiometabolic health, especially for individuals who do not need to lose weight for health.