Current recommendations for protein intake after bariatric surgery are not based on strong scientific evidence. It remains unclear how much protein should be eaten to minimize muscle loss and preserve the metabolism and function of individuals post-bariatric surgery. The objective of this study is to analyze the relationships between changes in body composition, nutrition and protein intake, and muscle function after bariatric surgery to further our understanding of the nutritional needs of patients after bariatric surgery. We intend to recruit around 75 participants, men and women, aged between 18 and 65 years. Participants will be recruited from the Bariatric Surgery Clinic, McGill University Health Center.