title: Waist to hip ratio and trunk to extremity fat (DXA) are better surrogates for IMCL and for visceral fat respectively than for subcutaneous fat in adolescent girls.
abstract: BACKGROUND
  Increased visceral adipose tissue (VAT) and intramyocellular lipids (IMCL) are associated with increased metabolic risk. Clinical and DXA body composition measures that are associated with VAT are generally even more strongly associated with subcutaneous adipose tissue (SAT) reflecting general adiposity, and thus are not specific for VAT. Measures more strongly associated with VAT than SAT (thus more specific for VAT), and predictors of IMCL have not been reported.
  
  
  METHODS
  We studied 30 girls 12-18 years; 15 obese, 15 normal-weight. The following were assessed: (1) anthropometric measures: waist circumference at the umbilicus and iliac crest (WC-UC and WC-IC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), (2) DXA measures: total fat, percent body fat (PBF), percent trunk fat (PTF), trunk-to-extremity fat ratio (TEFR), (3) MRI and 1H-MRS: VAT and SAT (L4-L5), soleus-IMCL.
  
  
  RESULTS
  Group as a whole: WC, trunk fat and PBF were more strongly associated with SAT than VAT; none were specific for VAT. In contrast, PTF and TEFR were more significantly associated with VAT (r = 0.83 and 0.81 respectively, p <0.0001 for both) than SAT (r = 0.77 and 0.75, p < 0.0001 for both). Strongest associations of S-IMCL were with WHR (r = 0.66, p = 0.0004). Subgroup analysis: In obese girls, WHR and WHtR were more strongly correlated with VAT (r = 0.62 and 0.82, p = 0.04 and 0.001) than SAT (r = 0.41 and 0.73, p not significant and 0.007), and for DXA measures, PTF and TEFR were more significantly associated with VAT (r = 0.70 and 0.72, p = 0.007 and 0.006) than SAT (r = 0.52 and 0.53, p = 0.07 and 0.06). In controls, PTF and TEFR were more strongly correlated with VAT (r = 0.79, p = 0.0004 for both) than SAT (r = 0.71 and 0.72, p = 0.003 for both). WHR was associated with IMCL in obese girls (r = 0.78, p = 0.008), but not controls.
  
  
  CONCLUSIONS
  Overall, WHR (anthropometry), and PTF and TEFR (DXA) are good surrogates for IMCL and for visceral fat respectively in adolescent girls.
authors.affiliation: Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA. mmisra@partners.org.
authors.forename: Eray
authors.initials: E
authors.lastname: Savgan-Gurol
authors.forename: Miriam
authors.initials: M
authors.lastname: Bredella
authors.forename: Melissa
authors.initials: M
authors.lastname: Russell
authors.forename: Nara
authors.initials: N
authors.lastname: Mendes
authors.forename: Anne
authors.initials: A
authors.lastname: Klibanski
authors.forename: Madhusmita
authors.initials: M
authors.lastname: Misra