BODY-MASS INDEX - A COMPARISON BETWEEN SELF-REPORTED AND MEASURED HEIGHT AND WEIGHT

Background Body mass index is used to measure obesity in individuals a nd to monitor trends in population obesity. Some observers use self-re ported height and weight to assess body mass index; others use measure d parameters. This paper reports on a study to compare body mass index when calculated from self-reported and measured heights and weights. Methods A randomized postal questionnaire survey and follow-up clinica l measurement study were carried out in a geographically defined popul ation in the rural South West of England; subjects were 6000 residents of Somerset health district aged 16-64 years selected from the Family Health Services Authority register. Results The response rate for the postal questionnaire was 57.6 per cent. A total of 73.3 per cent of r esponders ag reed to clinical measurements; 84 per cent of measured vo lunteers had over-reported their height and 74 per cent underreported their weight. The difference between body mass indices based on self-r eported and measured values of height and weight is highly statistical ly significant for the whole population and for most age-sex and body mass groups. Conclusions Self-reported heights and weights are unrelia ble and if used for monitoring health targets should be treated with c aution.