Introduction: This article aims to describe the effect of an intervention to promote the practice of voluntary Islamic fasting and its barriers among a group of overweight and obese Muslim women working in the public sector in Malaysia. Materials and methods: In this quasi-experimental study, an intervention to encourage voluntary fasting was delivered in a half day seminar, supported by relevant booklets prepared. A self-administered questionnaire was used to capture data on voluntary fasting practices and its perceived barriers before and four months after the intervention. Data was analysed using Mc Nemar test to compare the proportion before and after the intervention. Significant level was set at p