The aim of this study was to assess public knowledge about the effects of Ramadan fasting on various aspects of health and its association with fasting decision-making. This cross-sectional study was conducted on 600 subjects. The association between fasting and participants’ knowledge and attitudes toward Ramadan fasting, anthropometric measurements, physical activity, depression, anxiety, stress, dietary intake, and prior history of diseases was evaluated. The results indicated an adverse correlation between negative attitudes towards the effects of Ramadan fasting and adherence to fasting (P<0.0001). The prevalence of gastrointestinal disorders was higher in the non-fasting group (P=0.002). No significant association was found between other investigated variables and fasting adherence. It seems that negative thinking about the effects of Ramadan fasting may be inversely associated with fasting decision-making. Therefore, evidence-based educational programs may improve public knowledge and encourage fasting among eligible people.