Background and objectives: Obesity is a health condition in which there is the gathering of the body fat, which arises due to imbalance of intake and expenditure. In recent years Obesity in Saudi Arabia has increased tremendously and it is one of the main causes of the coronary artery disease and diabetes. Our study aims to investigate the reasons behind the prevalence and risk factors of obesity among medical students at Shaqra University, Saudi Arabia. Methods: One hundred fourteen medical students at Shaqra college of medicine participated randomly in a cross sectional study after obtaining their verbal consent. A standard questionnaire included: demographic data, anthropometric parameters, life style patterns, etc has been designed and distributed to the respondents. The obtained data was analyzed using SPSS version 20. Results: The BMI data showed that 8.8% medical students were underweight, 46.5% normal, 25.4% overweight and 19.3% were obese. The results clearly showed that only 46.5% were normal and the rest had abnormal BMI values. Our study showed that, there was not much effect on obesity by consuming the fast food. On the other hand, there was a significant effect of performing regular exercise on obesity. Interpretation & conclusions: Our study findings could be comparable with that reported in Saudi Arabia regarding prevalence of obesity and overweight. We concluded that, regular exercise is a cornerstone in antagonizing obesity while no significant effect of both fast and normal food consumption on it in young medical students.