Fat mass is negatively associated with cortical bone size in young healthy male siblings.
BACKGROUND
Body weight has been associated with bone mass and bone size through shared genetic determination and environmental influences. Whereas lean mass exerts a positive influence on bone size, the relationship between fat and bone remains unclear.


OBJECTIVE
The objective of the present study was to investigate the individual influence of fat mass and lean mass on volumetric bone density and size in young healthy male siblings at age of peak bone mass.


METHODS
This was a cross-sectional, population-based sibling pair study.


METHODS
A total of 677 men (25-45 yr) were included in this study with 296 independent pairs of brothers.


METHODS
Areal and volumetric bone parameters were determined using dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Body composition was determined by DXA. Sex steroids, leptin, and adiponectin were determined by immunoassay.


RESULTS
Total and regional fat mass were found to be inversely associated with areal bone mass and bone size, independent from lean mass (radius periosteal circumference beta: -0.29 +/- 0.04; P < 0.001). Lean mass was positively associated with bone size but inversely with cortical density at both tibia and radius (P < 0.01). The negative association between total fat mass and bone size was independent from sex steroid concentrations. Leptin but not adiponectin was inversely associated with bone size, but this was no longer significant after adjustment for body fat.


CONCLUSIONS
Increased fat mass is associated with smaller bone size, challenging the view of a high bone mass index as a protective factor for osteoporosis, whereas lean mass was a consistent positive determinant of bone size.
Taes
Youri E C
YE
Department of Endocrinology, Ghent University Hospital, Belgium.
Lapauw
Bruno
B
Vanbillemont
Griet
G
Bogaert
Veerle
V
De Bacquer
Dirk
D
Zmierczak
Hans
H
Goemaere
Stefan
S
Kaufman
Jean-Marc
JM
D054392:Adipokines / Q000097:blood; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000033:anatomy & histology*; D003430:Cross-Sectional Studies; D012739:Gonadal Steroid Hormones / Q000097:blood; D006262:Health; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology; D035781:Siblings
D054392:Adipokines; D012739:Gonadal Steroid Hormones