Effect of fasting in Ramadan on body composition and nutritional intake: A prospective study

Background: The present study aimed to assess the effects of Ramadan intermittent fasting on body weight and composition and the effects of age and sex. Methods: Body weight, height, waist and hip circumferences were measured, body mass index (BMI) was calculated and fat mass, fat-free mass and percentage body fat were assessed by bioelectrical impedance on 240 adult subjects (male: 158) who fasted between sunrise and sunset for at least 20 days. Measurements were taken 1 week before and 1 week after Ramadan. Energy and macronutrient intakes were assessed using a 3-day food frequency questionnaire on a sub-sample of subjects before and during Ramadan. Results: Subjects were grouped according to age and sex: ≤35 years (n = 82, males: 31) and 36-70 years (n = 158, males: 127). There were significant reductions in weight and BMI (P < 0.001) in almost all subjects, with the biggest being in males ≤35 years [-2.2% (SE 2.2%), P < 0.001]. Waist and hip circumferences fell in most subjects, except females aged 36-70 years. Fat mass fell in most subjects, ranging from 2.3% to 4.3% from baseline, except in females aged 36-70 years who did not experience a significant change. Fat-free mass was significantly reduced in all subjects (P < 0.001), whereas percentage body fat was lower only in males by 2.5% (SE 3.2%) (P = 0.029) in those aged ≤35 years and by 1.1% (SE 1.5%) (P < 0.001) in those aged 36-70 years. Dietary intake was similar before and during Ramadan, except in males whose protein intake fell during Ramadan (P = 0.032). Conclusions: Ramadan fasting leads to weight loss and fat-free mass reductions. Body composition changes vary depending on age and sex.