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theses

Caloric restriction (CR) results in loss of bone mass in older populations and has specifically been shown in women, but studies examining multiple bone sites and bone quality in response to weight loss (WL) in men are missing. In our six-month WL intervention, there was no reduction in bone mineral density (BMD) ay any anatomical sites in overweight and obese men. Also, WL did not affect cortical and trabecular bone and geometry. On the contrary, despite increased BMD at some sites when maintaining excess body weight, our results showed a trend for compromised cortical bone in the weight maintenance (WM) group. Postmenopausal women undergoing weight control to improve health outcomes, are particularly at risk for bone loss, and might benefit from supplemental vitamin D intake above the recommended allowance. A second study in this dissertation examined whether vitamin D supplementation, in healthy overweight/obese older women, affects bone mineral density (BMD) and bone structural parameters in a one year-long, randomized, double-blind controlled trial. Results showed that higher vitamin D supplementation prevented the decline in cortical thickness, and there was a trend to attenuate trochanter BMD in older women over one year. Evidence suggest that vitamin D supplementation influences osteocalcin (OC) levels during short-term caloric restriction and this results in lower insulin resistance (IR), Hence, we addressed whether vitamin D affects markers of insulin sensitivity and OC measures in healthy overweight/obese older women over one year. We found a modest effect of vitamin D supplementation on glycemic markers and no influence on OC measures. Overall, these studies examine bone structural parameters in response to weight loss in men and the effects of vitamin D supplementation on bone quality and metabolic health in older women.

ETD_7439

Ph.D.

Includes bibliographical references

by Liliana Claudia Pop

doi:10.7282/T3JS9SQB

ETD doctoral

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