title: Inverted BMI rather than BMI is a better proxy for percentage of body fat.
abstract: BACKGROUND
  Percentage of body fat (BF%) is a known risk factor for a range of healthcare problems but is difficult to measure. An easy to measure proxy is the weight/height(2) ratio known as the Body Mass Index (BMI kg/m(2)). However, BMI does have some inherent weaknesses which are readily overcome by its inverse iBMI (1000/BMI, cm(2)/kg).
  
  
  METHODS
  The association between BF% and both BMI and iBMI together with their distributional properties was explored using previously published data from healthy (n = 2993) and diseased populations (n = 298).
  
  
  RESULTS
  BMI is skewed whereas iBMI is symmetrical and so is better approximated by the normal distribution. The relationship between BF% and BMI is curved, but that of iBMI and BF% is linear and thus iBMI explains more of the variation in BF% than BMI. For example a unit increase in BMI for a group of thin women represents an increase of 2.3% in BF, but for obese women this represents only a 0.3% increase in BF-a 7-fold difference. The curvature stems from body mass being the numerator in BMI but the denominator in BF% resulting in a form of hyperbolic curve which is not the case with iBMI. Furthermore, BMI and iBMI have different relationships (interaction) with BF% for men and women, but these differences are less marked with iBMI.
  
  
  CONCLUSIONS
  Overall, these characteristics of iBMI favour its use over BMI, especially in statistical models.
authors.affiliation: Research Institute of Healthcare Sciences, University of Wolverhampton, Walsall, UK. a.m.nevill@wlv.ac.uk
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nevill
authors.forename: Antonios
authors.initials: A
authors.lastname: Stavropoulos-Kalinoglou
authors.forename: Giorgos S
authors.initials: GS
authors.lastname: Metsios
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Koutedakis
authors.forename: Roger L
authors.initials: RL
authors.lastname: Holder
authors.forename: George D
authors.initials: GD
authors.lastname: Kitas
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Mohammed
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology*; D000886:Anthropometry / Q000379:methods*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D016014:Linear Models; D008297:Male