Monday, October 08, 2012

Assessing Body Fat Using The New BAI (Body Adiposity Index)

To the line-up for assessing body mass (which includes weight, BMI or Body Mass Index, waist circumference, hip circumference, waist-to-hip ratio), we can now add the BAI or Body Adiposity Index, which approximates a person's body fat percentage using only hip and height measurements.

The calculation was put forth by Bergman et al.:
A Better Index of Body Adiposity, Nature: Obesity, March 2011
BAI = (hip circumference in centimeters / height in meters1.5) − 18

It supposedly correlates well with dual-energy X-ray absorptiometry (DXA). DXA actually measures body fat indirectly but is considered comparable to hydrostatic or underwater weighing.

Examples using BAI calculation:
  • A man with hips of 42" and height of 5'10" would have a body fat of about 27%.
  • A woman with hips of 36" and height of 5'4" would have a body fat of about 26%.

You can calculate your own BAI or body fat percentage here: Texas State University BAI Body Fat Calculator

None of these metrics (BMI, BAI, etc.) give an accurate measure of body composition, but taken together they give a better indication of health than any single measure:

The Body Adiposity Index (Hip Circumference ÷ Height1.5) Is Not A More Accurate Measure Of Adiposity Than Is BMI, Waist Circumference, Or Hip Circumference, Nature: Obesity, April 2012

The image at the top is from Wikipedia: Waist-Hip Ratio. I thought it offered a good reference for where to measure hips.


Dr. Mel said...

I've always wondered where to measure hips. This seems to be around the butt.

Bix said...

The hip measurement does include a lot of butt.