
Introduction: Physical activity is fundamental in lifestyle and is a determinant factor in body fat percentage. Physical inactivity leads to the risk of chronic noncommunicable diseases. Objective: To determine the relationship between physical activity and body fat percentage in gym users. Materials and methods: The study was quantitative and cross-sectional. The International Physical Activity Questionnaire (IPAQ) was used and skinfolds were used to determine body fat. The sample was 100 subjects. Spearman's Rho statistical test and Mann-Whitney U test were used. Results: 92% had a moderate level of physical activity and 5% a vigorous level, 34% had a normal body fat percentage and 17% low. There is a relationship between the level of physical activity and body fat (p=0.009; Rho=-0.259), likewise there is a relationship between body fat and age (p=0.032; Rho=0.215). Physical activity level (MET sedentary) was found to be a significant predictor of BMI (B=-0.004; β=-0.239; p=0.034). Conclusion: Gym users with a vigorous level of physical activity had a lower fat percentage compared to sedentary physical activity users who had a higher fat percentage. Higher levels of physical activity are associated with lower body mass index.