This study evaluated the effect of intermittent fasting during Ramadan, the Muslim religious season of fasting, on body composition among 95 adults (65 male adults) with a mean age of 45.4 years with metabolic syndrome in Iran. The individuals were classified retrospectively into fasting and nonfasting groups based on fasting for a minimum of 10 days during Ramadan. Body composition, physical activity, and dietary intake were assessed both at baseline before the fast began and after Ramadan. Those who fasted a minimum of 10 days had significant reductions in body weight (-1.5 kg) and body mass index, body fat mass (-1.2 kg), fat free mass (-0.4 kg), skeletal muscle mass (-0.3 kg), and visceral fat area (-5.7 cm2). Also, they showed significant decreases in the total body water, intracellular water, 50-kHz whole-body phase angle (-0.13 degrees), and total physical activity. Fasting resulted in a 1.5-kg weight loss, of which the percentage losses were loss in body fat mass, 76%; body water loss, 18%; and protein loss, 6%, and also decrease in daily dietary intake during fasting in those who fasted. Fasting during Ramadan, which restricts the time of eating and caloric restriction, may be effective as dietary interventions in patients with metabolic syndrome to reduce body weight, fat mass, and visceral fat while retaining lean mass.