MedicalResearch.com Interview with:
Sue Shapses, PhD
Professor, Department of Nutritional Sciences
Acting Chair, Department of Exercise Sciences and Sports Studies Rutgers, The State University
New Brunswick, NJ 08901-8525
MedicalResearch: What is the background for this study?
Dr. Shapses: Improving health outcomes through dieting and weight loss is encouraged for the majority of Americans who are either overweight or obese. However, while most studies show that a moderate reduction in body weight decreases obesity related comorbidities, there may also be loss of bone and muscle in older individuals. Specifically in postmenopausal women, intentional moderate weight loss results in a 1-2.5% bone loss when compared to a weight stable group. Studies in men, designed to address the effect of weight reduction at multiple bone sites, compartments and geometry, are currently lacking. In addition, while a higher body weight is associated with higher bone mass, evidence indicates that bone quality, a predictor of fracture risk, is compromised in the obese. It is possible that frequent dieting or weight cycling in these obese individuals may have deleterious effects on bone. Therefore, understanding whether bone quality changes with weight loss, is important to better predict osteoporosis risk in this population. In this controlled trial, the effect of dietary restriction on bone mineral density (BMD), geometry and strength were examined in middle aged and older obese/overweight men. In addition, we addressed whether endocrine changes associated with weight loss explain bone changes.
MedicalResearch: What are the main findings?
Dr. Shapses: Healthy men who adhered to a calorie restricted diet lost 8% reduction in body weight over six months, but did not reduce areal or volumetric BMD or alter bone geometric properties, as was expected based on studies in women of a similar age. In contrast, there was a trend to decrease cortical thickness and area only in the overweight/obese men who maintained their body weight, suggesting that factors associated with maintaining excess adiposity may lead to detrimental changes in cortical bone. Hormonal changes and differences in physical activity level could not explain bone differences between groups.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Shapses: Osteoporosis in aging men has become a public health burden. Previous studies indicate that obesity negatively affects bone quality and moderate weight loss reduces BMD in women. Our results in middle-aged and older men indicate that moderate weight loss is not detrimental to bone. In contrast, the men who maintained their body weight during the six month period of time showed a trend to decrease bone quality measures. Clinicians should encourage a healthy body weight in moderately older obese men not only for reducing traditional metabolic conditions, but also to potentially counterbalance the detrimental effects of excess weight on bone quality. It should also be kept in mind that patients with low body weight of any gender remain at highest risk of fracture.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Shapses: Hormones and other factors that are altered in obesity may contribute to changes in bone quality but because this is not clear, it should be addressed in longitudinal studies.