title: Excess body fat negatively affects bone mass in adolescents.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of excess body fat on bone mass in overweight, obese, and extremely obese adolescents.
  
  
  METHODS
  This study included 377 adolescents of both sexes, ages 10 to 19 y. Weight, height, body mass index (BMI), bone age, bone mineral content (BMC), and bone mineral density (BMD) were obtained by dual-energy x-ray absorptiometry. The results were adjusted for chronological age and bone age. Comparisons according to nutritional classification were performed by analysis of variance, followed by Tukey test. Linear regression models were used to explain the variation in BMD and BMC in the L1-L4 lumbar spinal region, proximal femur, and whole body in relation to BMI, lean mass, fat mass (FM), and body fat percentage (BF%), considering P < 0.05.
  
  
  RESULTS
  For all nutritional groups, average bone age was higher than chronological age. In both sexes, weight and BMI values increased from eutrophic to extremely obese groups, except for BMD and BMC, which did not differ among male adolescents, and were smaller in extremely obese than in obese female adolescents (P < 0.01). Significant differences were observed for FM and BF% values among all nutritional groups (P < 0.01). Positive, moderate to strong correlations were detected between BMD and BMC for BMI, lean mass, and FM. A negative and moderate correlation was found between BMC and BF%, and between BMD and BF% at all bone sites analyzed in males and between BF% and spine and femur BMD, in females.
  
  
  CONCLUSIONS
  The results reveal a negative effect of BF% on bone mass in males and indicate that the higher the BF% among overweight adolescents, the lower the BMD and BMC values.
authors.affiliation: Department of Pediatrics, Adolescent Medicine Course, Graduate Program in Gynecology, Obstetrics, and Mastology, Botucatu School of Medicine, São Paulo State University, UNESP, Brazil.
authors.forename: Luciana Nunes
authors.initials: LN
authors.lastname: Mosca
authors.affiliation: Department of Pediatrics, Adolescent Medicine Course, Graduate Program in Gynecology, Obstetrics, and Mastology, Botucatu School of Medicine, São Paulo State University, UNESP, Brazil. Electronic address: tamara@fmb.unesp.br.
authors.forename: Tamara Beres Lederer
authors.initials: TB
authors.lastname: Goldberg
authors.affiliation: Department of Pediatrics, Adolescent Medicine Course, Graduate Program in Gynecology, Obstetrics, and Mastology, Botucatu School of Medicine, São Paulo State University, UNESP, Brazil.
authors.forename: Valéria Nóbrega
authors.initials: VN
authors.lastname: da Silva
authors.affiliation: Department of Physical Education, University of North Paraná, Paraná, Brazil.
authors.forename: Carla Cristiane
authors.initials: CC
authors.lastname: da Silva
authors.affiliation: Clinical and Experimental Pediatric Research Center, Department of Pediatrics, Botucatu School of Medicine, São Paulo State University, UNESP, São Paulo, Brazil.
authors.forename: Cilmery Suemi
authors.initials: CS
authors.lastname: Kurokawa
authors.affiliation: Department of Pediatrics, Adolescent Medicine Course, Graduate Program in Gynecology, Obstetrics, and Mastology, Botucatu School of Medicine, São Paulo State University, UNESP, Brazil.
authors.forename: Anapaula C
authors.initials: AC
authors.lastname: Bisi Rizzo
authors.affiliation: Department of Statistics, Botucatu School of Medicine, São Paulo State University, UNESP, São Paulo, Brazil.
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: Corrente
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D001825:Body Fluid Compartments; D015992:Body Mass Index; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism*; D002648:Child; D005260:Female; D005269:Femur / Q000378:metabolism; D006801:Humans; D008159:Lumbar Vertebrae / Q000378:metabolism; D008297:Male; D063766:Pediatric Obesity / Q000378:metabolism*; D012737:Sex Factors; D055815:Young Adult
keywords: Adolescents; Bone mineral content; Bone mineral density; Obesity; Osteoporosis; Overweight