In conclusion, the present study shows for the first time that, although Ramadan intermittent fasting leads to body weight loss, only young subjects and males lost body fat, whereas all subjects experienced a significant reduction in fat-free mass. Further research is required to determine whether these changes are long-lasting and additive, thus contributing over the long term to signifi- cant body composition changes, which in turn may have implications on the basal energy requirements, particularly of women aged >36 years. Because these changes could not be attributed to dietary intake, further research is required to determine the possible mecha- nisms that are responsible, such as differences in macro- nutrient oxidation.