Background The aim is to evaluate the effects of IGB in overweight or class I obese patients, by analyzing body composition and quality of life (QOL). Methods Prospective study including patients with BMI 27–34.9 kg/m 2. body composition analysis (BCA) was performed before IGB implantation and its removal, after 6 months of treatment. QOL was assessed by the Short Form 36 (SF-36) Health Survey at baseline and after treatment. Results Forty patients were included in this study, but four were excluded. The total weight decreased by 12.29 kg after 6 months of use of IGB, which corresponds to loss of 13.69% of the total weight. There was a significant reduction in body fat mass and fat area. QOL improved in all eight sections analyzed ( p  < 0.001 to 0.041): functional capacity, physical aspects, pain, general health status, vitality, social aspects, emotional aspects, and mental health. Conclusions IGB induces not only weight loss but changes in body composition through the reduction of body fat mass and fat area. Furthermore, it improves QOL.