Intermittent fasting has become one of the most talked-about weight loss strategies online, often promoted as a metabolically superior approach to shedding pounds. A new Cochrane review suggests the evidence does not support that claim.
Researchers analyzed 22 randomized clinical trials involving 1,995 adults with overweight or obesity across North America, Europe, China, Australia and South America. The trials examined alternate-day fasting, periodic fasting and time-restricted eating, with most studies following participants for up to 12 months.
The review, published in the Cochrane Database of Systematic Reviews, found no clinically meaningful difference in weight loss between intermittent fasting and traditional dietary advice. Fasting also did not appear to produce greater weight loss than no intervention in the available data.
“Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” said Luis Garegnani, lead author of the review from the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre.
He emphasized that while fasting may be a reasonable option for some individuals, “the current evidence doesn’t justify the enthusiasm we see on social media.”
The review synthesized randomized trials, which are considered a higher standard of evidence than observational studies. However, many of the included studies were relatively small and short-term. Few extended beyond 12 months, limiting insight into long-term weight management.
“Obesity is a chronic condition. Short-term trials make it difficult to guide long-term decision-making for patients and clinicians,” Garegnani said.
The authors also noted that most participants were predominantly white adults living in high-income countries. As obesity continues to rise globally, findings may not apply equally across different populations, age groups or people with underlying health conditions.
“With the current evidence available, it’s hard to make a general recommendation,” said Eva Madrid, senior author from Cochrane Evidence Synthesis Unit Iberoamerica. “Doctors will need to take a case-by-case approach when advising an overweight adult on losing weight.”
The review does not conclude that intermittent fasting is ineffective. Rather, it suggests fasting does not appear to offer a distinct advantage over other calorie-reduction strategies. Across dietary approaches, sustained reductions in energy intake and long-term adherence remain key drivers of weight loss.
This review had no dedicated funding.