Associations of bone mineral density with lean mass, fat mass, and physical activity in young overweight and obese women - A feasibility study

Authors: GARVEY, MEGHAN - University Of Massachusetts; SHI, LING - University Of Massachusetts; LICHTENSTEIN, ALICE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MUST, AVIVA - Tufts University; HAYMAN, LAURA - University Of Massachusetts; CROUTER, SCOTT - University Of Tennessee; CAMHI, SARAH - University Of Tennessee

Submitted to: International Journal of Exercise Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2022
Publication Date: 4/25/2022
Citation: Garvey, M.E., Shi, L., Lichtenstein, A.H., Must, A., Hayman, L.L., Crouter, S.E., Camhi, S.M. 2022. Associations of bone mineral density with lean mass, fat mass, and physical activity in young overweight and obese women - A feasibility study. International Journal of Exercise Science. 15(7):585-598.

Interpretive Summary: The purpose of this study was to examine the associations between bone mineral density (amount of calcium and other minerals in bone), body composition (lean muscle mass and body fat) and physical activity in women who are overweight or obese. We found that bone mineral density was positively correlated with lean muscle mass and negatively correlated with body fat. When the data were analyzed on the basis of race, both of these findings remained significant in white women, but only lean muscle mass remained significant in Black women. When the data were analyzed on the basis of age, bone mineral density was positively correlated with lean muscle mass in younger women (<30y) but not older women. No significant relations were observed between bone mineral density and any physical activity measures. These findings indicate that, in young women who are overweight or obese, bone mineral density is significantly associated with body composition, both lean muscle mass and total fat, but not habitual physical activity. An emphasis on increasing lean muscle mass may be valuable for young women, particularly Black women, to improve bone health.

Technical Abstract: To examine the associations between bone mineral density (BMD), body composition and habitual physical activity in women who are overweight/obese. We measured whole-body bone, and body composition (lean mass, fat mass, and total fat percent) via dual-energy x-ray absorptiometry (model General Electric Lunar whole-body scanner) in a diverse group of women (N=48, age 26.6+/-4.7 years, 63% Black) living in an urban setting. The relations between BMD with total fat percent [%]), lean mass (kg), fat mass (kg), and physical activity were examined using Pearson correlations and multiple linear regression models, adjusted for race, age, and dietary calcium. BMD was positively correlated with lean mass (r=0.43, p=0.002) and negatively correlated with total fat percentage (r=-0.31, p=0.03). Multiple linear regression models indicated BMD was positively associated with lean mass (beta: 0.007, p<0.001), and negatively associated with fat mass (kg) and total fat percentage (beta: -0.003, p=0.03; beta: -0.004, p=0.03, respectively). When stratified by race, these relations were maintained in white women but only lean mass in Black women. When stratified by age, the positive correlation between BMD and lean mass was significant in younger women (<30y) only. There were no significant relationships between BMD and any physical activity measures. Our results indicate that in young women who are overweight/obese BMD is significantly associated with body composition, both lean mass and total fat percentage, but not habitual physical activity. An emphasis on lean mass accrual may be valuable for young women, particularly Black women, to improve bone health.