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.
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2 comments:

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.