This study was conducted in five provinces and food consumption, physical activity types and duration for 3 consecutive days were recorded in the questionnaire together with some general characteristics of 750 (320 males, 430 females) adults who were on fast during Ramadan at time of interview. One hundred and eighty-seven subjects had some type of health problems, among whom 60.4% were using drugs, and 31.6% were on diets; however, during Ramadan 9.7 and 18.8% of the subjects dropped taking drugs and did not regularly keep on diets, respectively. During the fasting time, from dawn to sunset, 34.3% of the subjects developed some behavioural disturbances, such as feeling tired and being unwilling to work. Although the meal consumed at dawn consisted of foods that were usually eaten at breakfast, the meal consumed at sunset consisted of a great variety of foods. Calcium intake was the most insufficiently consumed nutrient. It was observed that the daily energy intakes were less than the expenditures both in males and females. Further research should be done on the effects of fasting in health and disease.