title: Rate of fat gain is faster in girls undergoing early adiposity rebound.
abstract: OBJECTIVE
  To determine the changes in body composition (fat and lean mass) occurring in children during adiposity rebound (AR).
  
  
  METHODS
  Thirty-nine girls, 3 to 6 years of age at baseline, underwent yearly DXA scans for 2 years. An additional DXA scan was obtained 4 to 5 years after baseline. Age at AR was determined by modeling, and the velocity of change in height, weight, fat mass, and lean mass was estimated for each child using random coefficient models. Girls with an AR <5 years of age were classified as having an early AR, and those having an AR > or =5 years were classified as late AR.
  
  
  RESULTS
  Although body composition was similar at age 5, by age 9, girls with an early AR were significantly taller (3.5% more) and heavier (14.4%), with greater fat mass (50%) and percentage body fat (27%) than girls with a later AR. In addition, more girls were overweight according to BMI (18% vs. 6%) or percentage body fat (29% vs. 11%) at this time, despite no differences at baseline. Annual velocity of fat mass gain was over 2-fold higher in early compared with late rebounders (17.1% vs. 6.5%, p < 0.0001), with no difference in lean mass velocity (13.1% vs. 12.5%, p = 0.116).
  
  
  CONCLUSIONS
  Differences in BMI during AR were caused specifically by alterations in body fat and not by alterations in lean mass or height. Children undergoing early AR gained fat at a faster rate than children who rebounded at a later age.
authors.affiliation: Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, New Zealand. rachael.taylor@stonebow.otago.ac.nz
authors.forename: Rachael W
authors.initials: RW
authors.lastname: Taylor
authors.forename: Ailsa
authors.initials: A
authors.lastname: Goulding
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Lewis-Barned
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Williams
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000254:growth & development*; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D009765:Obesity / Q000453:epidemiology; D012307:Risk Factors