title: Relationship Among Body Fat Percentage, Body Mass Index, and All-Cause Mortality: A Cohort Study.
abstract: BACKGROUND
  Prior mortality studies have concluded that elevated body mass index (BMI) may improve survival. These studies were limited because they did not measure adiposity directly.
  
  
  OBJECTIVE
  To examine associations of BMI and body fat percentage (separately and together) with mortality.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Manitoba, Canada.
  
  
  METHODS
  Adults aged 40 years or older referred for bone mineral density (BMD) testing.
  
  
  METHODS
  Participants had dual-energy x-ray absorptiometry (DXA), entered a clinical BMD registry, and were followed using linked administrative databases. Adjusted, sex-stratified Cox models were constructed. Body mass index and DXA-derived body fat percentage were divided into quintiles, with quintile 1 as the lowest, quintile 5 as the highest, and quintile 3 as the reference.
  
  
  RESULTS
  The final cohort included 49 476 women (mean age, 63.5 years; mean BMI, 27.0 kg/m2; mean body fat, 32.1%) and 4944 men (mean age, 65.5 years; mean BMI, 27.4 kg/m2; mean body fat, 29.5%). Death occurred in 4965 women over a median of 6.7 years and 984 men over a median of 4.5 years. In fully adjusted mortality models containing both BMI and body fat percentage, low BMI (hazard ratio [HR], 1.44 [95% CI, 1.30 to 1.59] for quintile 1 and 1.12 [CI, 1.02 to 1.23] for quintile 2) and high body fat percentage (HR, 1.19 [CI, 1.08 to 1.32] for quintile 5) were associated with higher mortality in women. In men, low BMI (HR, 1.45 [CI, 1.17 to 1.79] for quintile 1) and high body fat percentage (HR, 1.59 [CI, 1.28 to 1.96] for quintile 5) were associated with increased mortality.
  
  
  CONCLUSIONS
  All participants were referred for BMD testing, which may limit generalizability. Serial measures of BMD and weight were not used. Some measures, such as physical activity and smoking, were unavailable.
  
  
  CONCLUSIONS
  Low BMI and high body fat percentage are independently associated with increased mortality. These findings may help explain the counterintuitive relationship between BMI and mortality.
  
  
  BACKGROUND
  None.
authors.forename: Raj
authors.initials: R
authors.lastname: Padwal
authors.forename: William D
authors.initials: WD
authors.lastname: Leslie
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Lix
authors.forename: Sumit R
authors.initials: SR
authors.lastname: Majumdar
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity; D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D008875:Middle Aged; D009026:Mortality; D009765:Obesity / Q000401:mortality; D050177:Overweight / Q000401:mortality; D016016:Proportional Hazards Models