Social media use is associated with body image concerns, disordered eating and body change behaviors in adolescents. This study aimed to examine these relationships within a biopsychosocial framework and test an integrated model. A sample of 681 adolescents (49% female), mean age = 12.76 years (SD = 0.74), completed a questionnaire assessing social media use, depression, self-esteem, body mass index, social media and muscular ideal internalization, appearance comparison, body dissatisfaction, disordered eating, and muscle-building behaviors. Path analysis was used to test the hypothetical model, which after modification revealed good fit to the data, although gender differences emerged. The findings suggest that biopsychosocial frameworks are useful for conceptualizing relationships between social media use and body image, eating, and muscle building outcomes.