Dt. Felson et al., EFFECTS OF WEIGHT AND BODY-MASS INDEX ON BONE-MINERAL DENSITY IN MEN AND WOMEN - THE FRAMINGHAM-STUDY, Journal of bone and mineral research, 8(5), 1993, pp. 567-573
We evaluated the association of weight and bone mass in elderly male a
nd female subjects of the Framingham osteoporosis study, a subset of t
he Framingham study cohort. By examining the differences in the correl
ations of weight with bone mass among men and women in weight-bearing
and non-weight-bearing sites and weight change since early adulthood,
we attempted to understand different ways in which weight or body mass
index affects bone mass. During biennial examination 20 of the Framin
gham cohort (1988-1989), 693 women and 439 men (mean age 76 years) had
proximal femur bone mineral density assessed by dual-photon absorptio
metry (DPA) and radius bone mass assessed by single-photon absorptiome
try. The majority of these subjects also had spine measurements by DPA
. Subjects had been weighed repeatedly over 40 years. After adjusting
for other factors affecting bone density, we found that both recent we
ight and body mass index explained a substantial proportion of the var
iance in bone mineral density for all sites in women (8.9-19.8% of tot
al variance, all p < 0.01) and for only weight-bearing sites (femur an
d spine) in men (2.8-6.9% of total variance, all p < 0.01). For bone m
ineral density at the proximal radius, weight and body mass index acco
unted for < 1% of variance in men (p NS). Weight change since biennial
examination 1 (1948-1951) was the strongest explanatory factor for bo
ne mineral density among women at all sites, but weight change did not
affect radius bone mineral density in men. The effect of weight and o
f weight change on bone mineral density was in general much less in me
n than in women. Our results suggest that the strong effect of weight
on bone mineral density is due to load on weight-bearing bones in both
sexes. The sex difference is unexplained but may be due to adipose ti
ssue production of estrogen in women after menopause.