Jerusalem, 9 February, 2026 (TPS-IL) — A long-term Israeli study is overturning a widely held belief about “yo-yo dieting,” suggesting that repeated attempts to lose weight may deliver lasting health benefits — even when the weight itself returns, Israeli scientists announced.
A study by researchers at Ben-Gurion University of the Negev indicates that healthy dietary changes can leave behind a durable “cardiometabolic memory” that reduces dangerous abdominal fat and improves metabolic health over many years.
“Repeated participation in a lifestyle program for weight loss, even after a perceived ‘failure,’ may lead to significant health benefits over the years, especially in reducing dangerous abdominal fat,” said Prof. Iris Shai of Ben-Gurion University of the Negev, the study’s senior author. Shai is also dean of sustainability at Reichman University and a professor at Harvard University.
The term “yo-yo dieting” describes a common cycle in which people lose weight through a structured lifestyle program but gradually regain it, often leading to repeated attempts. For decades, researchers and clinicians have debated whether these repeated efforts are worthwhile or potentially harmful. Some earlier studies suggested that repeated dieting could impair metabolism, worsen body composition or increase long-term health risks, while others found no clear negative effects.
What has been missing, the Ben-Gurion University team said, was long-term evidence that goes beyond body weight alone. Visceral fat — the fat that accumulates around organs such as the liver, pancreas and intestines — is considered particularly dangerous because it is metabolically active and linked to inflammation, cardiovascular disease, diabetes and metabolic syndrome. Body weight and BMI do not reliably reflect changes in this type of fat.
To address that gap, researchers from Ben-Gurion University of the Negev collaborated with colleagues from Harvard, Leipzig and Tulane Universities, along with Israel’s Dimona Nuclear Research Center, Soroka Hospital and the Berita Medical Center. They conducted a rare five- and 10-year follow-up of participants from two consecutive, controlled nutritional clinical trials. Each trial lasted 18 months and included about 300 participants, with roughly one-third enrolling in both studies.
The trials examined Mediterranean-style diets combined with physical activity, compared with control diets. Crucially, participants underwent repeated MRI scans before and after each intervention, allowing researchers to precisely measure changes in abdominal fat distribution and metabolic markers rather than relying solely on weight loss.
The results were striking. Although participants who joined the second intervention began at roughly the same weight as when they entered the first, their internal fat profile told a different story. MRI imaging showed that their abdominal fat distribution and metabolic indices were about 15-25 percent better than at the start of the initial trial, including improvements in insulin sensitivity and blood lipid levels.
“These findings suggest the existence of a positive cardiometabolic memory that persists even after weight regain,” the researchers reported, indicating that prior periods of healthy eating left lasting physiological effects.
Participants who repeated the program lost less weight during the second intervention, but they maintained their health gains more effectively over time. Five years after completing the second program, they showed less overall weight regain and significantly less accumulation of visceral fat compared with participants who took part in only one weight-loss intervention.
Hadar Klein, a PhD student and registered dietitian who served as the study’s lead author, said the findings challenge how success is typically defined. “Weight alone does not accurately reflect abdominal fat or blood parameters,” she explained. “Therefore, even if the weight comes back, it is very possible that health is still improved, and the success of a process cannot be defined solely by a number on the scale.”
Shai said the study directly challenges the notion that repeated weight-loss efforts are futile. “Even when the weight loss is smaller on the repeat attempt, the cumulative impact on belly fat and metabolic health is significant,” she said.
The findings give clinicians a stronger basis to encourage patients not to quit after weight regain. Even if weight rebounds, patients may still be reducing visceral fat and improving insulin sensitivity. They also support a shift away from weight-centric success metrics towards tracking waist circumference, metabolic markers and, where possible, imaging or surrogate measures of visceral fat. The research also strengthens the case for long-term, repeat-access lifestyle programs rather than one-off interventions.
Moreover, this changes how “relapse” is discussed. Weight regain can be framed as a partial physiological success rather than a total failure.
The study was published in the peer-reviewed BMC Medicine.
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