title: Abdominal fat is associated with lower bone formation and inferior bone quality in healthy premenopausal women: a transiliac bone biopsy study.
abstract: BACKGROUND
  The conventional view that obesity is beneficial for bone strength has recently been challenged by studies that link obesity, particularly visceral obesity, to low bone mass and fractures. It is controversial whether effects of obesity on bone are mediated by increased bone resorption or decreased bone formation.
  
  
  OBJECTIVE
  The objective of the study was to evaluate bone microarchitecture and remodeling in healthy premenopausal women of varying weights.
  
  
  METHODS
  We measured bone density and trunk fat by dual-energy x-ray absorptiometry in 40 women and by computed tomography in a subset. Bone microarchitecture, stiffness, remodeling, and marrow fat were assessed in labeled transiliac bone biopsies.
  
  
  RESULTS
  Body mass index (BMI) ranged from 20.1 to 39.2 kg/m(2). Dual-energy x-ray absorptiometry-trunk fat was directly associated with BMI (r = 0.78, P < .001) and visceral fat by computed tomography (r = 0.79, P < .001). Compared with women in the lowest tertile of trunk fat, those in the highest tertile had inferior bone quality: lower trabecular bone volume (20.4 ± 5.8 vs 29.1 ± 6.1%; P = .001) and stiffness (433 ± 264 vs 782 ± 349 MPa; P = .01) and higher cortical porosity (8.8 ± 3.5 vs 6.3 ± 2.4%; P = .049). Bone formation rate (0.004 ± 0.002 vs 0.011 ± 0.008 mm(2)/mm · year; P = .006) was 64% lower in the highest tertile. Trunk fat was inversely associated with trabecular bone volume (r = -0.50; P < .01) and bone formation rate (r = -0.50; P < .001). The relationship between trunk fat and bone volume remained significant after controlling for age and BMI.
  
  
  CONCLUSIONS
  At the tissue level, premenopausal women with more central adiposity had inferior bone quality and stiffness and markedly lower bone formation. Given the rising levels of obesity, these observations require further investigation.
authors.affiliation: Department of Medicine, Columbia University, College of Physicians and Surgeons, PH8-864 630 West 168th Street, New York, New York 10032, USA. ac1044@columbia.edu
authors.forename: Adi
authors.initials: A
authors.lastname: Cohen
authors.forename: David W
authors.initials: DW
authors.lastname: Dempster
authors.forename: Robert R
authors.initials: RR
authors.lastname: Recker
authors.forename: Joan M
authors.initials: JM
authors.lastname: Lappe
authors.forename: Hua
authors.initials: H
authors.lastname: Zhou
authors.forename: Alexander
authors.initials: A
authors.lastname: Zwahlen
authors.forename: Ralph
authors.initials: R
authors.lastname: Müller
authors.forename: Binsheng
authors.initials: B
authors.lastname: Zhao
authors.forename: Xiaotao
authors.initials: X
authors.lastname: Guo
authors.forename: Thomas
authors.initials: T
authors.lastname: Lang
authors.forename: Isra
authors.initials: I
authors.lastname: Saeed
authors.forename: X Sherry
authors.initials: XS
authors.lastname: Liu
authors.forename: X Edward
authors.initials: XE
authors.lastname: Guo
authors.forename: Serge
authors.initials: S
authors.lastname: Cremers
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Rosen
authors.forename: Emily M
authors.initials: EM
authors.lastname: Stein
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Nickolas
authors.forename: Donald J
authors.initials: DJ
authors.lastname: McMahon
authors.forename: Polly
authors.initials: P
authors.lastname: Young
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Shane
mesh_terms: D050153:Abdominal Fat / Q000502:physiology*; D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D001706:Biopsy; D015992:Body Mass Index; D015519:Bone Density; D001842:Bone and Bones / Q000473:pathology*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008875:Middle Aged; D010012:Osteogenesis; D017697:Premenopause; D012044:Regression Analysis
chemical_list: D007334:Insulin-Like Growth Factor I