Body size and shape: derivation of the "HAT" frame size model.

A bivariate mathematical model termed the "HAT" model for defining body frame size is presented for young males and females (mean age 22 yr). The HAT model is based on the relationship between stature and the sum of the biacromial and bitrochanteric diameter measurements. Small, medium, and large frame sizes were calculated for individuals and percentile rankings for the corresponding body weights, percentage fats, and lean body weights were given. For males, it was observed that differences in body weight between frame size groups was primarily due to differences in lean body weight. That is, lean body weight increased per frame size, while fat weight per frame size remained constant. For females in contrast, there was a small but statistically significant increase in fat weight per frame size and no increase in lean body weight per frame size.