Background: The aim of this review was to determine the optimal exercise program to prevent weight gain and maintain weight loss in patients after undergoing bariatric surgery. Materials and Methods: We conducted a systematic review in accordance with the PRISMA guidelines. We systematically investigated exercise training studies performed after bariatric surgery published from 2008 through 2018. Studies reporting changes in body composition, muscular strengths, aerobic capacity, functional capacity, walking distance, or relevant health outcomes were included. The review protocol is available from PROSPERO (CRD42018110174). Results: Seven articles were included in the review. The included studies reported data on 255 patients. The duration of intervention was between 4 and 26 weeks. The frequency of the session was two to five times per week and each session was similar to 30-80 min. Three studies used aerobic exercise for the intervention group, two studies planned resistance training, one study used an outpatient physiotherapy program that included breathing, strengthening, and stretching exercises, and one study used a combination of endurance and strengthening exercises. Conclusions: Gradually increasing low-moderate-intensity exercise, and a combination of aerobic, strength, and stretching-type exercise should be planned comprising a minimum 150-300 min per week in postoperative bariatric surgery patients to prevent weight gain and maintain weight loss.