Ann Intern Med

Fasting every other day leads to greater weight loss than daily caloric restriction

April 7, 2025

Compared with daily caloric restriction (DCR), 4:3 intermittent fasting (IMF) resulted in modestly greater weight loss among adults with overweight or obesity enrolled in a 12-month, high-intensity, comprehensive behavioral weight loss program.

Study details: This randomized trial compared the effects of 4:3 IMF and DCR on weight loss over 12 months in adults aged 18-60 years with a BMI of 27 to 46 kg/m². Participants in the IMF group restricted energy intake by 80% on three nonconsecutive days per week, while the DCR group reduced daily energy intake by 34%. Both groups received comprehensive behavioral support and were encouraged to engage in 300 minutes of moderate-intensity physical activity per week.

Results: Of the 165 participants, 125 completed the trial, with a higher completion rate observed in the IMF group. At 12 months, the IMF group experienced significantly greater weight loss (7.6%) compared with the DCR group (5%). The mean difference in weight loss between the two groups was 2.89 kg (95% confidence interval [CI], 5.65-0.14 kg; P = 0.040). The IMF group also showed more favorable changes in cardiometabolic markers, including lower systolic blood pressure, improved cholesterol levels, and reduced fasting glucose.

Source:

Catenacci VA, et al. (2025, April 1). Ann Intern Med. The Effect of 4:3 Intermittent Fasting on Weight Loss at 12 Months : A Randomized Clinical Trial. https://pubmed.ncbi.nlm.nih.gov/40163873/