Researchers dispel concerns about the yo-yo effect: Repeated weight loss is not harmful

"Der Versuch abzunehmen und auch dabei zu scheitern ist nicht schädlich", the researchers write. While weight often increases again after a diet, a causal connection between these fluctuations and concrete clinical harm in people with obesity cannot be derived from the existing literature. "Insgesamt stützen die derzeitigen Erkenntnisse keinen kausalen Zusammenhang zwischen Gewichtsschwankungen an sich und klinischen Schäden bei Menschen mit Adipositas."

The background to the analysis is a globally growing burden of overweight and obesity. As early as 2020, 43 percent of people in the USA were obese with a body mass index of 30 and above. Worldwide, around 2.5 billion people are currently considered overweight, and roughly 900 million are obese. Against this backdrop, about half of the world's population actively attempts to lose weight.

Why giving up can be harmful

At the same time, the Danish experts emphasize that giving up permanently can be harmful. "Aber ganz aufzugeben, das könnte schädlich sein", the experts say. Those who continue to reduce weight despite setbacks can benefit in the long term from improved metabolic markers, better cardiovascular health, and a higher quality of life. The summary states: "Die vorliegenden Erkenntnisse deuten darauf hin, dass die Vorteile einer wiederkehrenden Gewichtsreduktion – wie verbesserte Stoffwechselwerte, Herz-Kreislauf-Gesundheit und Lebensqualität – die potenziellen Risiken von Gewichtsschwankungen überwiegen."

The researchers also see nuances for modern therapies. With incretin-based treatments, colloquially known as "weight-loss injections" such as Mounjaro & Co., a rapid and significant weight loss is initially observed. If those affected discontinue the medication, however, a significant weight gain can occur – up to an increased risk of type 2 diabetes, fatty liver disease, high blood pressure, muscle loss, and cardiovascular disease. The experts therefore warn against abruptly stopping these therapies. Glukoseintoleranz könne sich dadurch verschlimmern, they write.

What does this mean for practice?

Clinical studies specifically investigating the yo-yo effect in test subjects do not yet exist. The Copenhagen group therefore relies on an evaluation of existing observational studies. This limits the validity of the conclusions but, in the researchers' view, provides a clear signal: The yo-yo effect is no reason to refrain from making further attempts to lose weight in the first place. "Scheitern" sei menschlich, the experts emphasize.

For practice, this means understanding repeated attempts at weight loss not as personal failure but as part of a long-term process. It is important to incorporate exercise and medical support alongside dietary changes in order to prevent muscle loss and metabolic problems. This shifts the focus away from the fear of relapses toward the question of how health improvements can be secured across multiple attempts.