title: Bone size and bone strength are increased in obese male adolescents.
abstract: BACKGROUND
  Controversy exists on the effect of obesity on bone development during puberty.
  
  
  OBJECTIVE
  Our objective was to determine differences in volumetric bone mineral density (vBMD) and bone geometry in male obese adolescents (ObAs) in overlap with changes in bone maturation, muscle mass and force development, and circulating sex steroids and IGF-I. We hypothesized that changes in bone parameters are more evident at the weight-bearing site and that changes in serum estradiol are most prominent.
  
  
  METHODS
  We recruited 51 male ObAs (10-19 years) at the entry of a residential weight-loss program and 51 healthy age-matched and 51 bone-age-matched controls.
  
  
  METHODS
  vBMD and geometric bone parameters, as well as muscle and fat area were studied at the forearm and lower leg by peripheral quantitative computed tomography. Muscle force was studied by jumping mechanography.
  
  
  RESULTS
  In addition to an advanced bone maturation, differences in trabecular bone parameters (higher vBMD and larger trabecular area) and cortical bone geometry (larger cortical area and periosteal and endosteal circumference) were observed in ObAs both at the radius and tibia at different pubertal stages. After matching for bone age, all differences at the tibia, but only the difference in trabecular vBMD at the radius, remained significant. Larger muscle area and higher maximal force were found in ObAs compared with controls, as well as higher circulating free estrogen, but similar free testosterone and IGF-I levels.
  
  
  CONCLUSIONS
  ObAs have larger and stronger bones at both the forearm and lower leg. The observed differences in bone parameters can be explained by a combination of advanced bone maturation, higher estrogen exposure, and greater mechanical loading resulting from a higher muscle mass and strength.
authors.affiliation: Department of Endocrinology, Ghent University Hospital, 9000 Ghent, Belgium. sara.vandewalle@ugent.be
authors.forename: S
authors.initials: S
authors.lastname: Vandewalle
authors.forename: Y
authors.initials: Y
authors.lastname: Taes
authors.forename: M
authors.initials: M
authors.lastname: Van Helvoirt
authors.forename: P
authors.initials: P
authors.lastname: Debode
authors.forename: N
authors.initials: N
authors.lastname: Herregods
authors.forename: C
authors.initials: C
authors.lastname: Ernst
authors.forename: G
authors.initials: G
authors.lastname: Roef
authors.forename: E
authors.initials: E
authors.lastname: Van Caenegem
authors.forename: I
authors.initials: I
authors.lastname: Roggen
authors.forename: F
authors.initials: F
authors.lastname: Verhelle
authors.forename: J-M
authors.initials: JM
authors.lastname: Kaufman
authors.forename: J
authors.initials: J
authors.lastname: De Schepper
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D000328:Adult; D015992:Body Mass Index; D015519:Bone Density; D001846:Bone Development; D002648:Child; D002657:Child Development; D004958:Estradiol / Q000097:blood; D005542:Forearm; D006801:Humans; D007866:Leg; D008297:Male; D024510:Muscle Development; D053580:Muscle Strength; D009765:Obesity / Q000097:blood / Q000473:pathology* / Q000503:physiopathology; D011859:Radiography; D011884:Radius / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D016474:Weight-Bearing; D055815:Young Adult
chemical_list: D004958:Estradiol