Intermittent fasting shows comparable weight loss to calorie restriction

A meta-analysis coordinated by the Harvard T. H. Chan School of Public Health and published in BMJ Medicine has examined the efficacy of intermittent fasting compared to traditional calorie restriction. The study reviewed 99 randomized trials involving 6,582 adults, most of whom had health issues and an average BMI of approximately 31.

The findings indicate that intermittent fasting produces weight loss results comparable to continuous calorie restriction. One specific method, alternate-day fasting, showed an average advantage of about 1.3 kg over calorie restriction. Other modest improvements were noted in waist circumference, total cholesterol, LDL, triglycerides, and C-reactive protein.

Research also highlights the importance of timing due to circadian rhythms. Early time-restricted feeding—concentrating meals in the morning or early part of the day—tends to offer better metabolic benefits, such as improved insulin sensitivity and glycemic stability, compared to late-day eating windows. However, researchers caution that many observed gains do not reach the threshold for clinical significance and emphasize the need for long-term studies to determine sustainability.