Intermittent Fasting Achieves Comparable Weight Loss to Calorie Restriction, Studies Find

Two recent clinical trials examined the effectiveness of intermittent fasting for weight management.

An 18‑month study by researchers at the University of Adelaide enrolled over 200 adults with obesity and compared early time‑restricted eating (30% of daily energy consumed between 8 a.m. and 12 p.m. on three non‑consecutive days) with continuous calorie restriction (about 70% of normal intake). After six months both diet groups lost roughly seven kilograms, while a standard‑care group lost about two kilograms. Participants on the fasting schedule reported needing less constant monitoring of food intake, indicating lower mental effort than traditional calorie‑counting diets.

A separate 12‑week intervention followed by a one‑year monitoring period involved 99 overweight adults in Spain and the United States. Early‑ and late‑window fasting groups maintained significantly greater weight loss after one year compared with a control group that ate for 12 hours or more each day. The timing of the eight‑hour eating window did not markedly affect outcomes, and about one‑third of participants continued fasting on their own during the follow‑up year, suggesting the approach is sustainable in real‑world settings.