Contrary to conventional clinical wisdom, greater body fat is associated with lower bone mineral density (BMD), particularly in men, an analysis of data from a large, nationally representative sample has found.
Dr Rajesh K. Jain
Much previous research has suggested that obesity protects against fractures and loss of BMD for a variety of reasons, including the beneficial effects of weight-bearing on the skeleton and hormonal factors linked to body fat. But the new findings should prompt a reconsideration of the relationship between obesity and fracture risk, according to the investigators, whose study appears in the latest issue of the Journal of Clinical Endocrinology & Metabolism.
"While higher BMI [body mass index] is generally associated with higher bone density, our study demonstrates that lean and fat mass affect bone density differently and that obesity is not a guarantee against osteoporosis," Rajesh K. Jain, MD, of the University of Chicago, Illinois, told Medscape Medical News.
Jain and a colleague, Tamara Vokes, MD, used multivariant modeling to examine the relationship between BMD and body composition of 10,814 men and women aged 20-59 years from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. All underwent total body DXA scans.
Participants were stratified into sex-specific quartiles based on lean mass index (LMI; lean mass divided by height squared) and fat mass index (FMI; fat mass divided by height squared).
