Objective: This study aimed to 1) compare the body mass index (BMI) and patterns of out-of-school activity participation in young people with and without physical disabilities, and 2) examine the relationship between BMI and the activity participation patterns among young people with physical disabilities. Methods: Thirty-nine young persons with physical disabilities (mean age ± standard deviation: 18.79 ± 1.99 years) and 70 healthy individuals (mean age ± standard deviation: 18.64 ± 0.74 years) participated in the study. The diversity, intensity, companionship, location and enjoyment of participation in activities were evaluated using the Children’s Assessment of Participation and Enjoyment (CAPE) scale. Body height and weight were obtained and BMI was calculated. Results: People with physical disabilities, regardless of their gender, had significantly lower CAPE-derived scores in almost all types of activity than the control participants (p < 0.05). Moreover, BMI was significantly higher in the group with physical disabilities than in the control group (p < 0.001). Regression analysis further showed that the CAPE score for physical activity explained 17.2% of the variance in BMI (p = 0.021). Conclusion: Young people with physical disabilities generally had lower levels of activity participation and a higher BMI than their healthy counterparts. The perception of enjoyment during physical activities was an important determinant of BMI in this group of participants.