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

Abstract

The present study aimed to assess the effects of Ramadan intermittent fasting on body weight and composition and the effects of age and sex. 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 20days. Measurements were taken 1week before and 1week 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. Subjects were grouped according to age and sex: ≤35years (n=82, males: 31) and 36-70years (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 ≤35years [-2.2% (SE 2.2%), P<0.001]. Waist and hip circumferences fell in most subjects, except females aged 36-70years. Fat mass fell in most subjects, ranging from 2.3% to 4.3% from baseline, except in females aged 36-70years 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 ≤35years and by 1.1% (SE 1.5%) (P<0.001) in those aged 36-70years. Dietary intake was similar before and during Ramadan, except in males whose protein intake fell during Ramadan (P=0.032). Ramadan fasting leads to weight loss and fat-free mass reductions. Body composition changes vary depending on age and sex.