Assessing the validity of body mass index standards in early postmenopausal women

Obes Res. 2002 Aug;10(8):799-808. doi: 10.1038/oby.2002.108.


Objective: To examine the relationship between percentage of total body fat (%Fat) and body mass index (BMI) in early postmenopausal women and to evaluate the validity of the BMI standards for obesity established by the NIH.

Research methods and procedures: Three hundred seventeen healthy, sedentary, postmenopausal women (ages, 40 to 66 years; BMI, 18 to 35 kg/m(2); 3 to 10 years postmenopausal) participated in the study. Height, weight, BMI, and %Fat, as assessed by DXA, were measured. Receiver operating characteristic analysis was performed to evaluate the ability of BMI to discriminate obesity from non-obesity using 38%Fat as the criterion value.

Results: A moderately high relationship was observed between BMI and %Fat (r = 0.81; y = 1.41x + 2.65) with a SE of estimate of 3.9%. Eighty-one percent of other studies examined fell within 1 SE of estimate as derived from our study. Receiver operating characteristic analysis showed that BMI is a good diagnostic test for obesity. The cutoff for BMI corresponding to the criterion value of 38%Fat that maximized the sum of the sensitivity and specificity was 24.9 kg/m(2). The true-positive (sensitivity) and false-positive (1--specificity) rates were 84.4% and 14.6%, respectively. The area under the curve estimate for BMI was 0.914.

Discussion: There is a strong association between %Fat and BMI in postmenopausal women. Current NIH BMI-based classifications for obesity may be misleading based on currently proposed %Fat standards. BMI >25 kg/m(2) rather than BMI >30 kg/m(2) may be superior for diagnosing obesity in postmenopausal women.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Absorptiometry, Photon
  • Adipose Tissue
  • Adult
  • Aged
  • Body Composition
  • Body Height
  • Body Mass Index*
  • Body Weight
  • Female
  • Humans
  • Middle Aged
  • National Institutes of Health (U.S.)
  • Obesity / diagnosis*
  • Postmenopause*
  • ROC Curve
  • Sensitivity and Specificity
  • United States