Whey Protein Supplementation and Lean Body Mass in Post-Bariatric Surgery Patients: A Randomized Controlled Trial
DOI:
https://doi.org/10.5281/zenodo.22337853Keywords:
whey protein, lean body mass, bariatric surgery, sarcopenic obesity, fat-free massAbstract
Background: Rapid weight loss after bariatric surgery is accompanied by substantial loss of fat-free mass, raising concern for
sarcopenic obesity. Objective: To synthesise randomised trial and meta-analytic evidence on whey protein supplementation and
lean body mass preservation after bariatric surgery. Methods: Narrative review of published randomised controlled trials,
systematic reviews and meta-analyses, and mechanistic studies. Findings: Pooled data from five RCTs show whey protein
supplementation attenuates fat-free mass loss (+3.87 kg) and fat mass loss (−2.10 kg) relative to control, with larger gains when
combined with resistance training. Conclusions: Whey protein is a plausible, low-risk adjunct for lean mass preservation, though
trial quality remains heterogeneous.
References
Mechanick, J.I., Apovian, C., Brethauer, S., Timothy Garvey, W., Joffe, A.M., Kim, J., Kushner, R.F., Lindquist, R., Pessah-Pollack, R., Seger, J., Urman, R.D., Adams, S., Cleek, J.B., Correa, R., Figaro, M.K., Flanders, K., Grams, J., Hurley, D.L., Kothari, S., Seger, M.V., Still, C.D. (2020) Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures - 2019 update. Obesity, 28(4): O1-O58.
Mendes, C., Carvalho, M., Bravo, J., Martins, S., Raimundo, A. (2025) How weight loss after bariatric surgery affects sarcopenia parameters and diagnosis. Surgeries, 6(2): 31.
Pekar, M., Horka, V., Hyvlova, D., Jirik, R., Uchytil, J., Rygelova, M., Kutac, P., Tomaskova, H., Vilimek, D., Holeczy, P., Maca, J., Buzga, M. (2026) Preliminary assessment of sarcopenic obesity risk after sleeve gastrectomy using dual-modality imaging: a six-month MRI and DXA pilot study in women. Frontiers in Aging, 7: 1913282.
Abiri, B., Valizadeh, M., Seifi, Z., Amini, S., Haidari, F. (2025) The role of nutritional factors in fat-free mass preservation and body composition changes after bariatric surgery: a systematic review of the available evidence. Eating and Weight Disorders, 30(1): 51.
Aills, L., Blankenship, J., Buffington, C., Furtado, M., Parrott, J. (2008) ASMBS Allied Health Nutritional Guidelines for the Surgical Weight Loss Patient. Surgery for Obesity and Related Diseases, 4(5 Suppl): S73-S108.
Nuijten, M.A.H., Eijsvogels, T.M.H., Sanders, B., Vriese, L.M., Monpellier, V.M., Hazebroek, E.J., Janssen, I.M.C., Hopman, M.T.E. (2023) Changes in fat-free mass, protein intake and habitual physical activity following Roux-en-Y gastric bypass surgery: a prospective study. Obesity Surgery, 33(7): 2148-2157.
Boirie, Y., Dangin, M., Gachon, P., Vasson, M.P., Maubois, J.L., Beaufrère, B. (1997) Slow and fast dietary proteins differently modulate postprandial protein accretion. Proceedings of the National Academy of Sciences, 94(26): 14930-14935.
Jäger, R., Kerksick, C.M., Campbell, B.I., Cribb, P.J., Wells, S.D., Skwiat, T.M., Purpura, M., Ziegenfuss, T.N., Ferrando, A.A., Arent, S.M., Smith-Ryan, A.E., Stout, J.R., Arciero, P.J., Ormsbee, M.J., Taylor, L.W., Wilborn, C.D., Kalman, D.S., Kreider, R.B., Willoughby, D.S., Hoffman, J.R., Krzykowski, J.L., Antonio, J. (2017) International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14: 20.
Frias-Toral, E., Chapela, S., Gonzalez, V., Martinuzzi, A., Locatelli, J., Llobera, N., Manrique, E., Sarno, G., Mingo, M., Marchese, F., Cuomo, R., Romaniello, L., Perna, M., Giordano, A., Santella, B., Schiavo, L. (2025) Optimizing nutritional management before and after bariatric surgery: a comprehensive guide for sustained weight loss and metabolic health. Nutrients, 17(4): 688.
Ito, M.K., Gonçalves, V.S.S., Faria, S.L.C.M., Moizé, V., Porporatti, A.L., Guerra, E.N.S., Canto, G.D.L., Baiocchi de Carvalho, K.M. (2017) Effect of protein intake on the protein status and lean mass of post-bariatric surgery patients: a systematic review. Obesity Surgery, 27(2): 502-512.
Alonso, L., Gastaldo, I., Caballero, M., Torres, F., Molero, J., Andreu, A., de Hollanda, A., Ibarzabal, A., Vidal, J., Moizé, V. (2025) Evaluating protein liquid supplementation for enhanced protein intake and adherence at short-term after metabolic and bariatric surgery: a pilot randomized controlled trial. Obesity Surgery, 35(9): 3517-3528.
Zaromskyte, G., Prokopidis, K., Ioannidis, T., Tipton, K.D., Witard, O.C. (2021) Evaluating the leucine trigger hypothesis to explain the postprandial regulation of muscle protein synthesis in young and older adults: a systematic review. Frontiers in Nutrition, 8: 685165.
Naclerio, F., Seijo, M. (2019) Whey protein supplementation and muscle mass: current perspectives. Nutrition and Dietary Supplements, 11: 37-48.
Faria, I., Samreen, S., McTaggart, L., Arentson-Lantz, E.J., Murton, A.J. (2025) The etiology of reduced muscle mass with surgical and pharmacological weight loss and the identification of potential countermeasures. Nutrients, 17(1): 132.
Gariballa, S.E., Al-Bluwi, G., Yasin, J. (2024) Physical activity and diet influence fat-free muscle mass preservation during intentional weight loss: a prospective longitudinal study. Nutrients, 16(23): 4044.
Lopes Gomes, D., Moehlecke, M., Lopes da Silva, F.B., Dutra, E.S., Schaan, B.D., Baiocchi de Carvalho, K.M. (2017) Whey protein supplementation enhances body fat and weight loss in women long after bariatric surgery: a randomized controlled trial. Obesity Surgery, 27(2): 424-431.
Lamarca, F., Vieira, F.T., Lima, R.M., Nakano, E.Y., Costa, T.H.M., Pizato, N., Dutra, E.S., Baiocchi de Carvalho, K.M. (2021) Effects of resistance training with or without protein supplementation on body composition and resting energy expenditure in patients 2-7 years post-Roux-en-Y gastric bypass: a controlled clinical trial. Obesity Surgery, 31(4): 1635-1646.
Taselaar, A.E., Boes, A.J., de Bruin, R.W.F., Kuijper, T.M., Van Lancker, K., van der Harst, E., Klaassen, R.A. (2023) PROMISE: effect of protein supplementation on fat-free mass preservation after bariatric surgery, a randomized double-blind placebo-controlled trial. Trials, 24(1): 1-12.
Zhao, X., Shi, T., Xie, X., Zhao, L., Guo, T. (2026) The potential effect of whey protein supplementation in post-bariatric surgery patients: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Nutrition, 13: 1832335.
Ranjbar, M., Fallah, M., Djafarian, K., Mohammadi, H., Mohammadi Farsani, G., Shab-Bidar, S. (2025) The effects of protein supplementation on body composition after bariatric surgery: a systematic review and meta-analysis of randomized controlled trials. Obesity, doi: 10.1002/oby.24283.
Romeijn, M.M., Holthuijsen, D.D.B., Kolen, A.M., Janssen, L., Schep, G., van Dielen, F.M.H., Leclercq, W.K.G. (2021) The effect of additional protein on lean body mass preservation in post-bariatric surgery patients: a systematic review. Nutrition Journal, 20: 27.
Jung, H.N., Kim, S-O., Jung, C.H., Lee, W.J., Kim, M.J., Cho, Y.K. (2023) Preserved muscle strength despite muscle mass loss after bariatric metabolic surgery: a systematic review and meta-analysis. Obesity Surgery, 33(11): 3422-3430.
Bellicha, A., Ciangura, C., Roda, C., Torcivia, A., Aron-Wisnewsky, J., Poitou, C., Oppert, J-M. (2022) Effect of exercise training after bariatric surgery: a 5-year follow-up study of a randomized controlled trial. PLOS ONE, 17(7): e0271561.
Vieira, F.T., Prado, C.M., Thorlakson, J., Johnson Stoklossa, C., Jin, J., Donini, L.M., Gramlich, L., Bielawska, B. (2025) Sarcopenic obesity in metabolic and bariatric surgery: a scoping review. Obesity Reviews, 26(12): e13973.
Carvalho, N.N.C., Martins, V.J.B., Modesto Filho, J., Pereira de Arruda Neta, A.C., Pimenta, F.C.F., de Brito Alves, J.L. (2023) Effects of preoperative sarcopenia-related parameters on the musculoskeletal and metabolic outcomes after bariatric surgery: a one-year longitudinal study in females. Scientific Reports, 13: 13373.
De Sousa-Coelho, A.L., Cardoso, P., Santos, T.V., Ramon-Krauel, M., Pais, S., et al. (2025) Impact of bariatric and metabolic surgery on sarcopenia-related parameters according to the EWGSOP2 consensus criteria in persons living with obesity. Obesity Surgery, 35(5): 1900-1910.
