A new international study challenges long-held beliefs about “yo-yo dieting,” suggesting that repeated cycles of weight loss and regain may offer lasting metabolic benefits, particularly in reducing visceral fat. The research, conducted by the University of Ben-Gurion del Néguev in Israel, and collaborators in the United States and Germany, indicates that the body may retain positive metabolic adaptations even after weight is regained.
For years, the phenomenon of losing and regaining weight – often referred to as the “yo-yo effect” – has been viewed as a sign of failure in weight management. However, the study, detailed in BMC Medicine, suggests this pattern isn’t necessarily detrimental. Researchers analyzed data from clinical trials, including the CENTRAL and DIRECT-PLUS trials, involving nearly 500 participants and follow-up periods of up to 10 years. Magnetic resonance imaging was used to quantify abdominal fat before and after interventions.
The analysis revealed that individuals who repeatedly engaged in structured weight loss programs demonstrated improved insulin sensitivity and more favorable lipid profiles, even after regaining weight. Participants who re-engaged in the trials showed enhanced metabolic markers and reduced visceral fat compared to their baseline measurements from the first intervention. Improvements included a 15 to 25% reduction in visceral fat and related risk biomarkers.
This “metabolic memory” means the body appears to retain favorable responses to weight loss attempts, independent of immediate changes on the scale. Even with a smaller amount of weight lost during a second intervention, the positive effects persisted long-term. Five years after the final intervention, those who participated in both programs experienced less weight and abdominal fat regain than those who completed only one attempt.
Researchers from the University Ben-Gurion del Néguev collaborated with institutions including the Nuclear Research Center Dimona, Briuta Medical Center, Soroka University Medical Center, Harvard, Tulane, and Leipzig during the study.
Further research, published in Nature, has begun to uncover the molecular mechanisms behind this phenomenon. Scientists at ETH Zurich in Switzerland, led by Dr. Ferdinand von Meyenn, discovered that obesity causes epigenetic changes in fat cells that persist even after weight loss. “Our study underscores the importance of prevention – a healthier diet, physical activity, and generally avoiding obesity in the first place,” Dr. Von Meyenn explained.
The research team at ETH Zurich analyzed fat cells from both mice and humans, finding that those with a history of obesity and subsequent weight loss maintained altered patterns of gene activity. These findings were corroborated in biopsies from patients who had undergone bariatric surgery at institutions in Sweden and Germany. While the duration of this “memory” within fat cells is still unknown, estimates suggest they can live for an average of ten years before being replaced.
Professor Iris Shai, the lead author of the recent study and Dean of the School of Sustainability at Reichman University, argues that these findings challenge the conventional focus on weight as the sole measure of success. “Persistent commitment to a healthy dietary pattern creates metabolic memory in the body,” she stated. Hadar Klein, a doctoral student and co-author at the University of Ben-Gurion del Néguev, added, “Body weight alone does not reflect changes in visceral fat or metabolic biomarkers. Even with weight regain, cardiometabolic health can continue to improve, and success should not be evaluated solely by the scale.”
The study employed rigorous methodology, utilizing controlled, randomized clinical trials primarily focused on the Mediterranean diet combined with physical activity, compared to conventional control strategies. Extensive follow-up periods, including magnetic resonance imaging and repeated biomarker analysis, were conducted on a sample of approximately 500 individuals across multiple international institutions. The research was funded by the Deutsche Forschungsgemeinschaft (DFG), the German Research Foundation, with no involvement from funders in the study’s design, analysis, or dissemination.
