Obesity is a major public health problem worldwide, affecting mostly adults of middle age but recently, also the young adults, mainly the college students. Increasing Stress and stress related disorder among students has become a major concern in college students. M.B.B.S. students, particularly, the 1st year students are more prone to stress due to hectic schedule, academic pressure, cultural and environmental change. Aims and Objectives: This research was done among the First year Medical students with the aim to study the obesity, the incidence and severity of stress and to see if there is any relationship between the stress and body mass index (BMI). Methodology: This study was conducted among 63 First year Medical students (2020-21 batch) of Jawaharlal Nehru Medical college, Belagavi. BMI and Stress were measured. The BMI was calculated by measuring the weight (in kg) and height (in meter) of students. Stress was studied by using a validated Medical Student Stressor Questionnaire (MSSQ). Result and Discussion: Out of 63 students of MBBS Phase -I, 34 students (53.96%) were of normal weight, 16 students (25.39 %) were overweight and 13 students (20.63%) were obese. Also 7 students had mild stress, 31 students had moderate stress, 19 students had high stress and 6 students had severe stress. Thus 25 students (39.68%) had high and severe stress. Out of these 25 highly and severely stressed students,12 students (48%) were normal weight, 11 students (44%) were overweight and 3 students (12%) were obese. On analysis, there is positive correlation between BMI and Stress level amongst the amongst the overweight and obese students. Conclusion: Overweight and obesity is seen in 46.02% of MBBS Phase –I students. Stress is one of the bio-determinant of obesity. This finding is consistent with the literature and promotion to adopt healthy lifestyles is urgently required