Ruff and Jamison described the trunk frame index (TFI) as a measure appropriate for comparing people with different body proportions. The authors are from the Johns Hopkins University and Indiana University.



(1) trunk frame size (see 02.16.02), derived from:

(1a) sitting height in cm

(1b) bi-iliac breadth (as a measure of relative body breadth) in cm

(2) body weight in kilograms


trunk frame size in square cm =

= (sitting height in cm) * (bi-iliac breadth in cm)


trunk frame index =

= (body weight in kg) / trunk frame size in square cm) * 1000



• The authors felt that the trunk frame size is more appropriate than stature for calculating body mass indices.

• The TFI shows less systematic bias than the body mass index (BMI), which tends to overestimate obesity in certain racial groups. It shows a better correlation with skinfold measurements in Inupiat children than the BMI.


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