A new review by Cochrane suggests that intermittent fasting may not lead to greater weight loss in overweight or obese adults compared to traditional dietary advice — or even compared to doing nothing.
Obesity remains a major global health challenge. According to the World Health Organization, worldwide adult obesity has more than tripled since 1975. In 2022 alone, an estimated 2.5 billion adults were overweight, including 890 million living with obesity. As rates continue to rise, many people have turned to intermittent fasting, a diet pattern that alternates between periods of eating and fasting, hoping for faster weight loss and metabolic benefits.
The Cochrane review analyzed data from 22 randomized clinical trials involving 1,995 adults across North America, Europe, China, Australia, and South America. The studies examined various forms of intermittent fasting, including alternate-day fasting, periodic fasting, and time-restricted feeding. Most trials followed participants for up to 12 months.
Researchers found no clinically meaningful difference in weight loss between intermittent fasting and standard dietary advice. In other words, fasting did not appear to provide additional benefits over conventional calorie-reduction strategies. Comparisons with no intervention also showed limited impact.
Luis Garegnani, lead author from the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre, said intermittent fasting “just doesn’t seem to work” as a superior strategy for weight loss in overweight or obese adults. He also cautioned that online enthusiasm may be outpacing scientific evidence.
The review highlighted limitations, including small sample sizes, inconsistent reporting of side effects, and a lack of long-term data. Most studies involved predominantly white populations in high-income countries, limiting generalizability.
Experts conclude that while intermittent fasting may suit some individuals, doctors should adopt a case-by-case approach when advising patients on weight loss.
REFERENCE: Garegnani, L. I., et al. (2026) Intermittent fasting for adults with overweight or obesity. Cochrane Database of Systematic Reviews. DOI: 10.1002/14651858.CD015610.pub2. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015610.pub2/full
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