The primary study endpoints will be adherence, tolerability, and total protein intake in bariatric surgery patients provided with a 12-week supply of ready-to-drink protein supplements. Secondary outcomes will evaluate the effect of a protein supplement on body composition (lean mass, fat mass, percent body fat, visceral fat, muscle thickness), resting metabolic rate, clinical and endocrine blood values, functional fitness, and responses to questionnaires evaluating mood, satiety, functional independence, and health related quality of life.