Is bone loss after gastric bypass surgery associated with the extent of weight loss?

This Practice Point commentary discusses a prospective study by Fleisher et al. that showed bone loss in response to extreme weight loss in 23 patients following Roux-en-Y gastric bypass surgery. The decline in BMD at the hip, but not at the spine or distal radius, was found to be proportional to the extent of weight loss. Although dietary calcium and vitamin D intake markedly increased after surgery, serum 25 hydroxyvitamin D, serum parathyroid hormone and urinary calcium levels remained at presurgery levels. Here, I highlight concerns about bone loss associated with severe weight loss, discuss mechanisms that might alter bone regulation during caloric restriction, and consider how diet might be used to prevent osteoporosis after weight-loss surgery.