BACKGROUND: Post-bariatric surgery may compromise nutritional status due to energy and protein intake restriction. METHODS: Systematic review was performed to synthesize evidence on the amount of protein intake and its association with lean mass and serum proteins during at least 6 months following Roux-en-Y gastric bypass or sleeve gastrectomy. RESULTS: Twelve studies (n = 739) were identified in the search. Protein intake below 60 g/day and significant lean mass loss were observed in majority of these studies. Of the four studies that measured association between protein intake and lean mass retention, only two supported this hypothesis. CONCLUSION: There is insufficient evidence of the effect of dietary protein on serum protein levels. Further studies are needed to better estimate the protein intake that supports a healthy nutritional status in this population.