Validity of self-reported height and weight and derived body mass index in middle-aged and elderly individuals in Australia

Aust N Z J Public Health. 2011 Dec;35(6):557-63. doi: 10.1111/j.1753-6405.2011.00742.x. Epub 2011 Sep 12.


Background: Body mass index (BMI) is an important measure of adiposity. While BMI derived from self-reported data generally agrees well with that derived from measured values, evidence from Australia is limited, particularly for the elderly.

Methods: We compared self-reported with measured height and weight in a random sample of 608 individuals aged ≥ 45 from the 45 and Up Study, an Australian population-based cohort study. We assessed degree of agreement and correlation between measures, and calculated sensitivity and specificity to quantify BMI category misclassification.

Results: On average, in males and females respectively, height was overestimated by 1.24 cm (95% CI: 0.75-1.72) and 0.59 cm (0.26-0.92); weight was underestimated by 1.68 kg (-1.99- -1.36) and 1.02 kg (-1.24- -0.80); and BMI based on self-reported measures was underestimated by 0.90 kg/m2 (-1.09- -0.70) and 0.60 kg/m2 (-0.75- -0.45). Underestimation increased with increasing measured BMI. There were strong correlations between self-reported and measured height, weight and BMI (r=0.95, 0.99 and 0.95, respectively, p<0.001). While there was excellent agreement between BMI categories from self-reported and measured data (kappa=0.80), obesity prevalence was underestimated. Findings did not differ substantially between middle-aged and elderly participants.

Conclusions: Self-reported data on height and weight quantify body size appropriately in middle-aged and elderly individuals for relative measures, such as quantiles of BMI. However, caution is necessary when reporting on absolute BMI and standard BMI categories, based on self-reported data, particularly since use of such data is likely to result in underestimation of the prevalence of obesity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Aging / physiology
  • Anthropometry
  • Body Height*
  • Body Mass Index*
  • Body Weight*
  • Cohort Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • New South Wales / epidemiology
  • Obesity / epidemiology*
  • Reproducibility of Results
  • Self Disclosure*
  • Sensitivity and Specificity
  • Surveys and Questionnaires / standards