Bariatric surgery is one of the treatments for severe obesity, with proven efficacy in reducing weight and diseases associated with obesity. Weight loss associated with bariatric surgery is greatly associated with a significant reduction of skeletal muscle and bone mineral mass, which leads us to induce that after bariatric surgery, patients incur an increased risk of sarcopenia. The need for prophylactic programs that prevent sarcopenia in bariatric surgery patients seems to be one of the crucial points for the long-term surgical success of bariatric and metabolic surgery. The aim of this randomized clinical trial will be to study the effects of a 16-week supervised exercise intervention program on the prevention of sarcopenia, in patients undergoing bariatric surgery. As a secondary purpose, it is also intended to characterize metabolic risk factors, physical fitness, and quality of life in post-bariatric surgery patients.A total of 45 patients on the waiting list for bariatric surgery and who have subsequently perfurgery, will be include on EXPOBAR (This study will provide the effects of a physical exercise on sarcopenia, in patients after bariatric surgery.The trial was registered at Clinicaltrials.gov NCT03497546.