Objective: To determine if there are variations in the body mass index associated with changes in eating habits and physical activity in first semester students of a private university in Lima, Peru. Materials and methods: An observational, prospective cohort study was conducted in the faculty of health sciences of a private university located in Lima, Peru during the months of March and June 2015. The participants were evaluated anthropometrically and 2 self- applied instruments: the IPAQ short version and the eating habits questionnaire were applied. Results: 120 participants were enrolled and 109 (91%) remained until the final stage. The average age of the evaluated ones was 18.6 years for both genders, predominating the feminine one with 65.1%. It was found that around 80% of those evaluated had inadequate feeding habits in both phases and only one participant changes from having inadequate to adequate habits (0.9%). Likewise, the majority of students presented an adequate BMI in both phases despite the predominant slight physical activity evidenced in both moments. It should be mentioned that of the 23 students who presented variations in their BMI, only one (5.6%) increased or decreased their level of physical activity. Conclusion: No association was found between variations between changes in BMI and variations in eating habits and physical activity. Likewise, it was evidenced that most of the students present inadequate eating habits and low levels of physical activity regardless of nutritional status.