Is it harmful to your health to lose weight repeatedly and then gain it back again? In a recent article in ‘Nature Reviews Endocrinology’, DZD researchers Prof. Norbert Stefan and Prof. Faidon Magkos of the University of Copenhagen offer a sophisticated assessment: The deciding factor could be the starting weight. While they appear to be less problematic in people with obesity than is often assumed, weight fluctuations could increase the risk of developing obesity in the long term among people of normal weight.
Losing weight, gaining it back, losing it again: Many people are familiar with this “yo-yo effect.” In the scientific community, this repeated fluctuation in body weight is referred to as “weight cycling.” For a long time, there was concern that such weight fluctuations could lead to further weight gain and increase the risk of related metabolic disorders.
However, the current analysis paints a more nuanced picture. According to the authors, the health risk associated with weight cycling depends largely on whether a person is of normal weight or is already obese. In people with obesity, repeated cycles of weight loss and weight regain appear to have only minor—or possibly no—additional negative effects on weight and body composition in the long term [1]. For people of normal weight—especially those with a predisposition to obesity—the situation may be different.
Body composition offers one possible explanation for these differences: The key factor is which tissues are lost when you lose weight and are rebuilt when you gain weight again. When losing a significant amount of weight, people of normal weight lose a proportionally greater amount of fat-free body mass—which includes muscle mass—than people with obesity. At the same time, their resting energy expenditure decreases more significantly. If weight is subsequently regained, a disproportionately large portion of that weight may consist of fat tissue. If taking place repeatedly, this process could increase the risk of developing obesity over the long term in individuals having a corresponding predisposition.
Faidon Magkos emphasizes that voluntary weight loss by no means applies only to people who are overweight: “Remarkably, nearly 30% of people who are neither overweight nor obese want to lose weight and have already tried to do so in the past.” In addition to a partly hereditary predisposition to weight fluctuations, social factors may also play a role, such as ideals of thinness and the fear of obesity.
This issue has taken on added relevance due to the increasing availability of effective weight-loss medications. Norbert Stefan points out that even people of normal weight or those who are only slightly overweight try to obtain such medications outside their approved indications—for example, for cosmetic reasons or in the hope of long-term health benefits.
That is why it is especially important for metabolically healthy people who are not significantly overweight to carefully weigh their options. According to the authors, when prescribing weight-loss medications, doctors should weigh the potential benefits against the potential risks.
For people with obesity, the analysis conveys an important message: Fear of a possible yo-yo effect shouldn't keep you from losing weight. According to the authors, there isn’t currently sufficient evidence to suggest that repeated attempts to lose weight in cases of existing obesity further worsen long-term weight trends.
The situation may be different for people of normal weight. For these individuals, repeated dieting followed by weight gain could be detrimental in the long term, especially if they already have a genetic predisposition to obesity or one caused by other factors. These individuals should therefore be informed about the potential risks of unnecessary weight-loss attempts.
At the same time, the authors emphasize that the hypothesis requires further examination. In particular, future studies should directly compare the long-term effects of repeated weight loss and weight gain in people with and without obesity.
Nature Reviews Endocrinology
Commentary/editorial
People
Effects of weight cycling in the presence and absence of obesity
2-Nov-2026