The aim of the study is to compare two different bariatric procedures performed in patients with 65 years or more: gastric bypass and sleeve gastrectomy. Primary outcomes will be weight loss, control of comorbidities and morbidity of the operation. Secondary outcomes are related to functionality, that will be evaluated with specific tests.

Introduction: Surgical treatment of obesity in patients over 65 years of age is controversial. For patients in this age group, there is a prevailing concept that the risk / benefit ratio of the procedure should be evaluated for each individual patient, without determining objective criteria or outcomes that characterize this benefit. Increased surgical risk in patients older than 65 years is undoubtedly a limiting factor for the broader indication of bariatric surgery in this population. The two most applied surgical techniques are Sleeve Gastrectomy and Roux-en-Y Gastric Bypass. Most of the studies that evaluated the two techniques in elderly patients are retrospective, prospective non-randomized, or contemplated only one technique. Recent, studies concluded that in the elderly the weight loss with Gastric Bypass was higher, but the surgical morbidity with the Sleeve was lower and there was no difference in the resolution of comorbidities between the two techniques. In evaluating the benefits of surgery, most studies address outcomes such as weight loss and control of metabolic and cardiovascular comorbidities. Outcomes that are specific to the treatment of obesity in the elderly, such as improvement of functionality, decreased fragility and improvement of the quality of life have not been studied yet. In this field, there is concern that excessive weight loss, accompanied by loss of muscle mass may compromise the mentioned parameters, especially in individuals who already have loss of bone and muscle mass before surgery. For this reason, the assessment of bone mass and body composition in the preoperative period of these individuals is fundamental. In order to identify the benefits of weight loss promoted by surgery and life expectancy, the elderly patients in preparation for operation at the Bariatric Surgery Unit of the Hospital das Clinicas University of São Paulo School of Medicine are submitted to a geriatric evaluation, which includes the analysis of their functional dependency profile, Important prognostic factor in this population. Objectives: The primary objective of the study will be to evaluate surgical morbidity and short-term (weight loss, comorbid control) outcomes of surgical treatment of obesity in patients over 65 years of age, comparing two techniques: Sleeve Gastrectomy (SG) and Gastric Bypass (GB). The secondary objective will be to evaluate the body composition of the individuals, before and after the surgery, comparing the two techniques. Patients and methods: This is a prospective study, in which 40 consecutive patients, aged 65 years and over, will be admitted to the Bariatric and Metabolic Surgery Unit of the Discipline of Digestive System Surgery of Hospital das Clinicas University of São Paulo School of Medicine with indication criteria for bariatric surgery. Patients will be randomized into two groups according to the surgical technique to be used: SG or GB. Data related to surgical morbidity, weight loss, control of comorbidities, nutritional deficiencies, changes in body composition and functionality will be evaluated and compared after a follow-up of at least 12 months.

Inclusion Criteria:

• BMI over 40 Kg/m2 for at least 5 years with failure of obesity medical treatments
• BMI over 35 Kg/m2 with at least 2 comorbidities and failure of medical treatments

Exclusion Criteria:

• prior bariatric surgery
• clinical or psychological conditions that contraindicate bariatric surgery

The plan is to publish the complete data after the end of the study