 Previous studies had suggested that lifestyle therapy diet plus exercise resulting in weight loss in elderly population improves physical function, cardio metabolic risk factors, and cognitionquality of life, but a major complication is loss of BMD. The addition of exercise to diet-induced weight loss attenuated but did not eliminate weight-loss-induced reduction of BMD. Moreover, while long-term maintenance of weight loss and physical function was feasible, sustained lifestyle change led to continued loss of hip BMD, which might predict hip fractures. Although similar BMD loss with weight loss has been observed in younger populations, BMD loss in older adults might be of particular concern because of aggravation of age-related bone loss. Moreover, the belief that obesity protects against fractures has now been challenged by studies demonstrating that obesity is associated with poor bone quality and ankle and leg fractures.Because of previous lack of options to assess bone quality in vivo, there has been little or no scientific study of the possibility that lifestyle therapy in obese older adults improves bone quality. This study represents an unprecedented opportunity to prove the hypothesis that lifestyle therapy intervention improves bone quality and thus, may confer a protective rather than adverse effect on bone health. This will be the first randomized controlled trial RCT to comprehensively assess bone quality using novel techniques in response to lifestyle therapy in obese older adults, with major ramifications with regards to defining optimal treatment strategies for this increasingly high-risk older population. 