title: How does bone quality differ between healthy-weight and overweight adolescents and young adults?
abstract: BACKGROUND
  Overweight youth have greater bone mass than their healthy-weight peers but sustain more fractures. However, it is unclear whether and how excess body fat influences bone quality in youth.
  
  
  OBJECTIVE
  We determined whether overweight status correlated with three-dimensional aspects of bone quality influencing bone strength in adolescent and young adult females and males.
  
  
  METHODS
  We categorized males (n=103; mean age, 17 years) and females (n=85; mean age, 18 years) into healthy-weight and overweight groups. We measured lean mass (LM) and fat mass (FM) with dual-energy x-ray absorptiometry (DXA). We used high-resolution peripheral quantitative CT to assess the distal radius (7% site) and distal tibia (8% site). Bone quality measures included total bone mineral density (Tt.BMD), total area (Tt.Ar), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), separation (Tb.Sp), and thickness (Tb.Th). We used multiple regression to compare bone quality between healthy-weight and overweight adolescents adjusting for age, ethnicity, limb length, LM, and FM.
  
  
  RESULTS
  Overweight males had higher (10%-21%) Tt.BMD, BV/TV, and Tb.N and lower Tb.Sp at the tibia and lower Tt.Ar at the radius than healthy-weight males. No differences were observed between overweight and healthy-weight females. LM attenuated the differences in bone quality between groups in males while FM negatively predicted Tt.BMD, BV/TV, Tb.N, and Tb.Th.
  
  
  CONCLUSIONS
  Our data suggest overweight males have enhanced bone quality compared with healthy-weight males; however, when group differences are interpreted in the context of the mechanostat theory, it appears bone quality of overweight adolescents adapts to LM and not to greater FM.
authors.affiliation: Robert H. N. Ho Research Centre, 7/F, 2635 Laurel Street, Vancouver, BC, V5Z 1M9, Canada.
authors.forename: Christa L
authors.initials: CL
authors.lastname: Hoy
authors.forename: Heather M
authors.initials: HM
authors.lastname: Macdonald
authors.forename: Heather A
authors.initials: HA
authors.lastname: McKay
mesh_terms: D015502:Absorptiometry, Photon; D000222:Adaptation, Physiological; D000293:Adolescent; D000886:Anthropometry; D001835:Body Weight; D015519:Bone Density; D001955:British Columbia; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D050177:Overweight / Q000503:physiopathology*; D011884:Radius / Q000000981:diagnostic imaging* / Q000502:physiology*; D012044:Regression Analysis; D011795:Surveys and Questionnaires; D013977:Tibia / Q000000981:diagnostic imaging* / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult