JERUSALEM — Repeated cycles of weight loss and regain, known as yo-yo dieting, delivered lasting reductions in harmful visceral fat among nearly 500 adults tracked for up to 10 years, researchers at Ben-Gurion University of the Negev reported Wednesday.

The study followed participants from two controlled trials comparing Mediterranean-style diets and exercise routines to standard methods. Investigators used MRI scans to measure visceral fat, the type that wraps around organs and drives risks for heart disease and Type 2 diabetes. Even those who gained back pounds before joining a second trial showed striking results.

Among repeat dieters, visceral fat dropped 15% to 25% from the research’s start, according to the findings. Insulin sensitivity climbed. Blood lipid profiles shifted toward healthier levels. Five years after completing the second program, these participants had regained less weight overall and carried less abdominal fat than one-time dieters.

Weight cycling starts simply enough. People diet and exercise. Pounds vanish. Then stress, holidays or routine disruptions bring them back. Another round follows. Past studies flagged risks from this pattern. Wednesday’s analysis challenges that view. Regaining weight did not erase gains in fat distribution or metabolic function, the researchers concluded.

Body weight alone paints an incomplete picture, they emphasized. Visceral fat reductions held up over time. Such changes link to lower disease odds long-term. Public health experts have long discouraged yo-yo dieting as futile or dangerous. This work suggests otherwise for many who try multiple times.

The trials drew from Israeli adults, mostly overweight or obese, averaging ages in the 40s and 50s. First trial participants numbered 278. A subset of 209 later enrolled in the second after at least six months. Researchers adjusted for age, sex and baseline traits in their comparisons.

Lead investigator Iris Shai, a professor of epidemiology and nutrition at Ben-Gurion, called the outcomes encouraging. ‘People shouldn’t give up after one attempt,’ she said in the summary. The team plans further work on why metabolic benefits endure.

Yo-yo dieting affects millions. In the U.S., surveys show 40% to 50% of dieters regain lost weight within a year. Israel’s findings could shift messaging from doctors and weight loss programs. Focus might tilt from perfect adherence to sustained efforts, visceral fat as a key target.

Limitations exist. The study centered on structured programs, not self-directed efforts. Participants stuck closer to guidelines than typical dieters. Still, real-world parallels abound. Many chase Mediterranean patterns — olive oil, fish, vegetables, nuts — for health beyond slimming.

Broader implications loom for obesity fights. With global rates topping 1 billion adults, per World Health Organization data, any edge from common behaviors counts. Reducing visceral fat by even 10% slashes diabetes risk sharply, separate research affirms. Yo-yo dieters in this cohort cleared that bar.