Which works best for weight loss? Intermittent fasting or traditional dietary advice?

There are various techniques recommended for weight loss. Intermittent fasting is one such method.

This Cochrane systematic review assessed whether intermittent fasting (IF) is more effective than traditional dietary advice or no intervention for weight loss in adults living with overweight or obesity. IF strategies included time-restricted eating, alternate-day fasting, and periodic fasting, compared with calorie restriction, dietary modification, or waiting-list/no treatment controls.

The review included 22 randomized controlled trials involving 1,995 participants, conducted mainly in community or home-based settings across Europe, North America, China, Australia, and South America. Study duration and IF protocols varied substantially, and many trials had relatively small sample sizes.

When compared with traditional dietary advice, intermittent fasting resulted in little to no difference in weight loss, measured as change from baseline body weight. Similarly, there was no meaningful difference in quality of life, although this outcome was reported in only a small number of participants. Evidence was uncertain regarding the likelihood of achieving a clinically relevant ≥5% weight loss and regarding adverse events such as fatigue, headache, or nausea, due to imprecision and methodological limitations.

When compared with no intervention or a waiting list, intermittent fasting also likely made little to no difference in weight loss. Evidence for quality of life and adverse events in this comparison was sparse and of low certainty. Importantly, none of the included studies reported outcomes on diabetes status, broader cardiometabolic health, overall morbidity, or patient satisfaction, limiting conclusions about longer-term health impact.

Overall confidence in the evidence was moderate for weight loss outcomes versus no treatment, but low to very low for most other outcomes, reflecting small study sizes, risk of bias, and inconsistent reporting.

Clinical implication: Intermittent fasting does not appear superior to conventional dietary advice for weight loss in adults with overweight or obesity. Clinicians should prioritise individual preference, safety, and long-term adherence when recommending dietary strategies, rather than promoting intermittent fasting as a more effective option.

LINK

Garegnani LI, Oltra G, Ivaldi D, Burgos MA, Andrenacci PJ, Rico S, Boyd M, Radler D, Escobar Liquitay CM, Madrid E. Intermittent fasting for adults with overweight or obesity. Cochrane Database of Systematic Reviews 2026, Issue 2. Art. No.: CD015610. DOI: 10.1002/14651858.CD015610.pub2. Accessed 26 February 2026.