Does Ramadan Fasting Alter the Resting Metabolic Rate, Body Composition and Dietary Intake of Overweight and Obese Adults?

Ramadan fasting (RF) is a model of calorie restriction similar to intermittent fasting, which is extensively practiced by a large population of Muslims. Limited and controversial studies have investigated the physiological changes induced by 30 days of RF. The present study aimed to evaluate the effects of Ramadan fasting on the resting metabolic rate and body composition of overweight and obese individuals.  This study was conducted on 21 men and women aged 18-40 years. The subjects avoided eating and drinking for one month during the holy month of Ramadan (at least 20 days) and received a routine diet without an intervention between Iftar and dawn (Sahur). Before and after the study, the energy of the basal metabolic rate was measured via indirect calorimetry, and body composition was measured by bioimpedance (InBody s10). In addition, the physical activity of each participant was evaluated using a pedometer during one week. During the study, each participant received a 24-hour recall once a week.  Compared to the pre-study period and after four weeks of RF, body weight (77.91±11.83 vs. 77.01 ±11.75 kg; P<0.05) decreased, while the body fat percentage (34.84±7.07 vs. 38.48±5.93%; P<0.001) increased. However, the resting metabolic rate had no significant changes (P=0.641), while the total fat-free mass and visceral fat mass significantly deceased after the study (P<0.001). The mean daily energy intake increased after the study compared to before RF (3,290±785.82 vs. 2,458±535.32 kcal; P<0.05). Moreover, the total carbohydrate and sugar intake increased significantly after RF (437.04±101.02 and 194.04±56.87 g per day vs. 310.09±87.12 and 60.42±31.57 g per day).  According to the results, RF may effectively improve metabolic parameters and prevent the decline of the basal metabolic rate if accompanied by nutritional support and healthy dietary recommendations.