Alternate-Day Fasting Is No Better Than a Typical Reduced-Calorie Diet

Among the many approaches to dieting, alternate-day fasting has become increasingly popular. In this controlled trial, 100 obese but otherwise healthy adults (mean body-mass index, 35 kg/m²; mean age, 44; mostly women) were randomized to alternate-day fasting, daily calorie restriction, or a control group. Baseline energy expenditure was measured during a 1-month run-in phase. Alternate-day participants were instructed to consume 25% of their calculated energy needs on fast days and 125% of their needs on alternating “feast” days; reduced-calorie participants were told to lower their daily calorie intake to 75% of energy needs. Control participants were asked to maintain their weight and, on study completion, received free dietary counselin…