University of Copenhagen Jun 24 2026 Reviewed Many people experience fluctuations in body weight throughout their lives, and so‑called yo‑yo dieting has long been considered a health risk – in some cases even more harmful than remaining overweight. It has, for example, been associated with negative health effects such as increased fat mass, loss of muscle mass, reduced metabolic rate and a higher risk of diseases including type 2 diabetes and cardiovascular disease. However, careful evaluation