title: Predictors of body fat gain in nonobese girls with a familial predisposition to obesity.
abstract: BACKGROUND
  Conflicting evidence exists on the causal factors underlying the development of excess adiposity in children.
  
  
  OBJECTIVE
  We determined the effect of energy expenditure (EE), muscle energetics, and physical fitness on weight and fat gain in prepubertal girls with or without a predisposition to obesity.
  
  
  METHODS
  Normal-weight girls (n = 101) were recruited at 8 y of age according to parental body mass index. Eighty-eight girls completed the 2-y study, and the groups were as follows: LN, girls with 2 lean parents; LNOB, girls with 1 obese and 1 lean parent; and OB, girls with 2 obese parents. Measurements of weight, height, and body composition were taken 1 and 2 y after baseline. Girls underwent baseline measurements of EE by 24-h calorimetry and doubly labeled water, of muscle metabolism by (31)P nuclear magnetic resonance, and of fitness.
  
  
  RESULTS
  Fat mass (FM) and percentage body fat (%BF) differed significantly between the groups at years 1 and 2; the OB group had higher FM (P = 0.03) and %BF (P = 0.046) at year 1 and higher FM (P = 0.047) at year 2 than did the LN group. After adjustment for baseline weight, group, time, ethnicity, and Tanner stage, sleep EE, basal EE, 24-h EE, and peak oxygen uptake were negatively associated with FM and %BF (P < 0.04). After adjustment for the same variables, muscle oxidative capacity and free-living total EE were negatively and positively predictive, respectively, of changes in %BF between 8 and 10 y of age (both P = 0.04).
  
  
  CONCLUSIONS
  Nonobese girls with 2 obese parents have a significant risk of developing obesity. High free-living total EE and low muscle oxidative capacity predict high rates of fat gain.
authors.affiliation: Center for Human Nutrition, The Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205-2179, USA. mtreuth@jhsph.edu
authors.forename: Margarita S
authors.initials: MS
authors.lastname: Treuth
authors.forename: Nancy F
authors.initials: NF
authors.lastname: Butte
authors.forename: John D
authors.initials: JD
authors.lastname: Sorkin
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D001481:Basal Metabolism; D001823:Body Composition; D002151:Calorimetry; D002648:Child; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009765:Obesity / Q000235:genetics* / Q000378:metabolism*; D010101:Oxygen Consumption; D010290:Parents; D010809:Physical Fitness; D011627:Puberty; D015430:Weight Gain