Body mass index as a measure of body fatness in the elderly

Body composition was assessed in a group of 35 apparently health elderly males and 37 elderly females, aged 60-83 years, by means of anthropometry and densitometry. Mean body mass index (BMI) of the males was 25.0 +/- 2.2 kg/m2 and of the females 25.9 +/- 3.2 kg/m2, which indicates normal weight to only minor overweight. Body fat as assessed by densitometry was 31 per cent in men and 44 per cent in women, a rather high value, especially when compared to the rather low BMI. Body fat percentage as calculated from the sum of four skinfolds (bicipitalis, tricipitalis, subscapularis and supra-iliacalis) using regression equations from the literature was 27.9 +/- 2.5 per cent and 38.7 +/- 3.2 per cent for men and women respectively. These values are probably an underestimation of the body fat, due to a higher proportion of internal fat in elderly subjects, which is not measured by skinfolds. Body fat percentage as determined by the BMI has an estimation error of about 4 per cent when derived from sex- and age-specific regression equations. The body fat percentage as predicted from skinfold thicknesses had a comparable error of estimate. These prediction errors in the body fat percentage in the elderly are comparable with the prediction errors found in young and middle-aged subjects as reported in the literature.