Objective:To determine the effects of fasting on weight and eventually on Body Mass Index (BMI) in medical students of a Public Sector Medical CollegeMethods:It was a prospective analytical study conducted in a Public Sector Medical College in Peshawar City from 28thMarch to 20thMay 2022 (1443 Hijri). Convenience Sampling was used and 115 students (58 male and 57 female) of 1stYear MBBS to Final Year MBBS were enrolled. Four readings of weight were taken, one before, two during, and one after Ramadan. A well-structured self-administered questionnaire was used to inquire about basic demographic characteristics, sleep patterns during Ramadan and normal routine, and family history of obesity. The collected data were analyzed through SPSS software and a repeated measures ANOVA test was used for drawing statistical conclusions.Results:A slight increase in the mean weight was observed during the second week of Ramadan while a loss of 0.4 kg occurred during the fourth week of Ramadan, F (1, 81) = 1777.55; p < 0.0001. The same pattern was observed for BMI, F (1, 81) = 2705.18; p < 0.0001. However, the weight and the BMI were regained in two to three weeks following Ramadan.Conclusion:Ramadan offers a non-hazardous way of weight loss. Further studies across different geographical locations with larger sample sizes should be conducted to identify and quantify the association between weight and fasting and also to identify potential confounders.