Impact of protein supplementation after bariatric surgery: A randomized controlled double-blind pilot study

•Protein supplementation after bariatric surgery leads to increased loss of body fat mass within six mo.•Protein supplementation after bariatric surgery leads to decreased loss of lean body mass within six mo.•Protein supplementation after bariatric surgery supports reaching the recommended goals regarding protein intake.•Protein supplementation after bariatric surgery does not deteriorate markers of renal function.