Bariatric surgery currently relies on combinations of restrictive and malabsorptive procedures. Early decreases in bone mineral density (BMD) have been reported. However, the accuracy of dual-energy X-ray absorptiometry used to measure BMD can be diminished by the major weight loss, whereas quantitative computed tomography (QCT) measurements are less affected. The nutritional deficiencies induced by mixed bariatric surgery procedures, together with changes in hormones produced by adipocytes and/or the gastrointestinal tract, are often associated with elevations in serum levels of bone resorption markers. Although the data are limited, the incidence of fractures does not seem higher after bariatric surgery than in non-operated obese patients.