A major review has found that intermittent fasting may offer little benefit for adults who are overweight or obese, challenging the popular perception that fasting on certain days or restricting eating windows leads to significant weight loss.
Researchers analyzed 22 previous studies involving nearly 2,000 adults from Europe, North America, China, Australia, and South America. The review compared intermittent fasting approaches, such as the 5:2 diet, time-restricted eating, and alternating fasting days, with standard dietary advice or no advice at all. The studies followed participants for up to 12 months.
The findings indicate that intermittent fasting made little to no difference in weight loss or quality of life compared with traditional dietary advice, which focuses on reducing calorie intake and eating healthily. It also showed minimal effect compared to participants who received no guidance on weight management. Researchers said confidence in the results was moderate, as many studies had small sample sizes and did not use the most robust methods.
Luis Garegnani, lead author of the review from the Universidad Hospital Italiano de Buenos Aires, expressed concern about the online hype surrounding fasting. “Intermittent fasting may be a reasonable option for some people, but the current evidence doesn’t justify the enthusiasm we see on social media,” he said.
The review, published in the Cochrane Database of Systematic Reviews, noted that intermittent fasting could still offer other health benefits. It may improve certain body functions or metabolic markers, although more research is needed to evaluate its impact on conditions such as type 2 diabetes. The study also highlighted gaps in evidence regarding differences between men and women, varying body mass indexes, and effects across populations in different countries.
Experts stressed that public perception of intermittent fasting often exceeds the scientific evidence. Dr. Baptiste Leurent, associate professor at University College London, said the review shows a “clear indication that intermittent fasting offers little benefit” and represents another example of the mismatch between public enthusiasm and research.
Emeritus Professor Keith Frayn from the University of Oxford added that claims about fasting’s “special effects on metabolism” are largely unsupported. He emphasized that there are no quick fixes for weight loss beyond reducing calorie intake and maintaining a balanced diet.
While intermittent fasting remains popular, especially on social media, the review underscores that it may not provide advantages over conventional dieting for people trying to lose weight. Around 1.6 million adults in the UK are currently using weight loss injections such as Wegovy and Mounjaro, mostly through private prescriptions, but studies show that stopping these treatments can lead to rapid weight regain.
The research suggests that individuals seeking long-term weight management may need to focus on sustainable lifestyle changes rather than short-term fasting strategies.
