Background: During Ramadan, observant Muslims fast from sunrise to sunset for a month. Knowing whether Ramadan fasting affects body weight has implications for health advice to the Muslim community, for understanding the effects of skipping meals on body weight, and for general weight management advice.
Methods: We compared body weight before and after the Ramadan fast and 1 month later in observant Muslims attending a Mosque in East London, UK.
Results: In 202 participants who provided weight at the beginning and the end of Ramadan, there was a small weight decrease (-0.84 kg, 95% CI = -0.6 to -1, P < 0.0001), with 46% of participants losing >1 kg. Participants who fasted throughout Ramadan lost significantly more weight (1 kg) than those who occasionally broke fast (0.3 kg, P = 0.013). In 87 participants who provided weight at the beginning and end of Ramadan and also 1 month later, all the lost weight was regained (+0.1 kg, 95% CI = 0.2-0.5, P = 0.504 compared with baseline).
Conclusions: Observers of Ramadan lose on average about a kilogram of weight over 4 weeks, and the lost weight is quickly regained. Current weight management treatments generally assume that skipping meals leads to weight gain and advise against it. The finding suggests that further research is needed on the justification of the 'do not skip meals' advice.