Body mass index charts of Women

A chart showing the Body Mass Index of Women, changing with age. Quite interesting, really. I bet you haven't seen this chart anywhere else!

Womens BMI chart

 

Notice the "median" BMI value, which is the 50th percentile Red line. Compare it to the CDC definition of "Overweight" at BMI of 25. This is where the experts derived the famous statistic, that over 50 percent of American Women have a BMI over 25 and hence are considered overweight.

Also notice the gradual increase in Women's body mass index over time, until age 50-60. After that, a gradual decrease in BMI occurs in older women. Each percentile line has a curved shape, even for skinny women at 25th and 10th percentiles. ( I'm hinting, without much subtlety, that a curved line is better model than a flat line across BMI=25. I'm hinting, that some weight gain during adult life is "natural".)

The chart shows how girls BMI increases with age, even beyond age 20. The children's data came from the standard CDC growth charts. There is a gap between the children's and adult data, because the data sources are different. The adult data (from the NHANES III survey) is more recent ( 1988-1994 ), whereas the body-mass-index-for-age charts from the CDC are based from a mix of data from old and recent sources.

This page also shows a Men's body mass index chart (below). Comparing Women to Men, you'll notice some differences. At less than 50th percentile, men have a higher BMI than women, which is generally thought to be due to men's greater skeletal muscle mass. But after age 30, for the 50th percentiles or higher, overweight women rise to higher BMI levels than men. Why is that? Probably because if a woman is going to be overweight, her body accumulates fat in breasts and hips, which are places that men's fat accumulation doesn't occur. This female trait probably explains the higher BMI levels in overweight women.


Mens BMI chart

 

I realize the charts can be hard to read, so the table below shows actual numbers:

The "National Average" Median Body Mass Index values for Women are:
Age: 20-29 yrs30-39 yrs40-49 yrs50-59 yrs60-69 yrs
Median BMI:

24.4

26.4

27.8

28.4

27.5

 

Surf onward to:

Created by Steven B. Halls, MD, FRCPC and John Hanson, MSc.
Last modified 24-May-2008

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