Intermittent Fasting Reduces Body Weight Versus Ad Libitum Diet

MONDAY, June 30, 2025 (HealthDay News) — Intermittent-fasting strategies yield small reductions in body weight compared with an ad libitum diet, according to a study published online June 18 in The BMJ.

Zhila Semnani-Azad, Ph.D., from the Harvard T.H. Chan School of Public Health in Boston, and colleagues examined the effect of intermittent-fasting diets with continuous energy restriction or unrestricted (ad libitum) diets on intermediate cardiometabolic outcomes in a systematic review and network meta-analysis. The study included 99 randomized clinical trials involving 6,582 adults.

The researchers found that when compared with an ad libitum diet, all intermittent-fasting and continuous energy restriction diet strategies reduced body weight. Alternate-day fasting was the only form of intermittent-fasting diet strategy to show benefit in body weight reduction compared with continuous energy restriction (mean difference, −1.29 kg). Alternate-day fasting showed a trivial reduction in body weight when compared with both time-restricted eating and whole-day fasting (mean difference, −1.69 and −1.05 kg). Among trials with less than 24 weeks follow-up, estimates were similar, but benefits in weight reduction were only seen in diet strategies compared with ad libitum in moderate-to-long-term trials (≥24 weeks). Compared with time-restricted eating, alternate-day fasting lowered total cholesterol, triglycerides, and nonhigh-density lipoprotein in comparisons between intermittent-fasting strategies. Time-restricted eating resulted in a small increase in total cholesterol, low-density lipoprotein cholesterol, and nonhigh-density lipoprotein cholesterol compared with whole-day fasting.

“In our analysis, intermittent-fasting strategies showed trivial to small improvements in body weight reduction,” the authors write.

Several authors disclosed ties to relevant organizations.

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