en Bariatric Surgery Bariatric Surgery Review/Systematic Review Review/Systematic Review <strong>Background:&nbsp;</strong>Bariatric surgery is considered the most effective treatment for morbid obesity. Despite the successful weight loss, as result of bariatric surgery, patients are susceptible to protein deficiency. Change in food intake after surgery can cause some nutritional deficiencies. The aim of this study was to determine the status of protein before and after bariatric surgery<br> <strong>Methods: </strong>The systematic search was performed in April 2021. Cochrane, PubMed, and google scholar databases were used for our literature search by searching these keywords: body composition, fat free mass, bariatric surgery, protein malnutrition and protein intake.<br> <strong>Results: </strong>Our studies showed few evaluation of protein has been done before surgery in candidates for surgery. Obesity surgery reduces muscle mass and serum protein so evaluation of these factors is necessary. Bariatric surgery method exposes people to protein malnutrition and changes in body composition therefore more attention to their protein intake needs to be done.<br> <strong>Conclusion: </strong>Based on our results dietary intake can affect the outcome of surgery, so, we recommended evaluating protein status and lean body mass before and following the bariatric surgery. Also, the effect of different types of protein supplementation to improve body composition can be assessed in further studies. Bariatric surgery, Body composition, Protein intake 9 14 http://annbsurg.iums.ac.ir/browse.php?a_code=A-10-62-2&slc_lang=en&sid=1 Taiebeh Mohammadi Farsani tmfarsani@gmail.com 10031947532846001914 10031947532846001914 No Department of Medical Biotechnology , Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran Masoumeh Khalighi Sikaroudi 10031947532846001915 10031947532846001915 No Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. . Minimally Invasive Surgery Research Center, Iran University of Medical Sciences, Tehran, Iran Parisa janmohammadi 10031947532846001916 10031947532846001916 No Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. . Minimally Invasive Surgery Research Center, Iran University of Medical Sciences, Tehran, Iran Hana arghavani 10031947532846001917 10031947532846001917 No Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. . Minimally Invasive Surgery Research Center, Iran University of Medical Sciences, Tehran, Iran Reza Yaghubi-Tabar 10031947532846001918 10031947532846001918 No Department of Medical Biotechnology , Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran Gholamreza Mohammadi Farsani mohammadigh53@gmail.com 10031947532846001919 10031947532846001919 Yes Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. . Minimally Invasive Surgery Research Center, Iran University of Medical Sciences, Tehran, Iran