Study on the Effect of Intermittent Fasting on Body Mass Index, Physical Activity and Sleep in Adults

Abstract

Introduction: Recently, Intermittent Fasting (IF) has gained popularity as an effective approach for obesity management. Many types of IF have been practiced for either religious or health purposes. Muslims, for example, are encouraged by Islam to voluntarily fast two days/week (Monday and Thursday) from sunrise to sunset. Aim: This study investigated the association between Muslims’ voluntary fasting (two days/week) with Body Mass Index (BMI), Physical Activity (PA), and sleep pattern. Materials and Methods: The present survey-based study was conducted for three months on 1242 adults (245 males and 997 females) who completed the completed self-administered study questionnaire. The questionnaire comprised questions on sociodemographic and anthropometric variables, fasting-related questions, PA, and sleep pattern. Participants were classified into fasting and non-fasting groups according to their responses to the question “Do you fast two days (i.e., Monday and Thursday) every week? The differences between the two groups were tested using Chi-square test, an exact probability test and unpaired t-test. Results: A total of 1,242 valid responses (age 18 years and above) were collected. Among those participants, only 18.4% (n=229) reported fasting Monday and Thursday every week. The BMI of those who used to fast two days/week was significantly higher (p < 0.05) than those who did not fast. The desire to lose weight (47.59%), followed by religious views (44.54%) were the main reasons for fasting. A significant difference (p < 0.05) in PA was observed between the two groups, but overall, the participants were involved in low PA only. No significant differences (p ≥ 0.05) in sleep pattern, such as sleepiness during the day, and sleep duration were observed between the two groups. However, significant differences in the time required to sleep and waking up during sleep were found between the two groups. Conclusion: This study indicated that fasting two days/week does not affect BMI when meal timings are restrained to early evening and pre-dawn periods, with adequate night sleep. It may be an appropriate beginning point to further develop strategies to sustain any beneficial effects of the voluntary IF on obesity.