Why BMI Alone Is Not The Best Indicator Of Weight For Black Women

Body Mass Index Chart - Feet and PoundsWhen I was in high school we measured our body mass index (BMI) in health class. My BMI said I was overweight. Now I was about 16, an athlete running MILES a day with a good parent-controlled diet. In fact I had skinny legs and was made fun of for being too skinny “for a black girl”. So why was it that my BMI came back overweight, but the white girl of the same height and lifestyle was not overweight according to the BMI?

First thing to know is that BMI doesn’t take into account muscle mass. Muscle is more dense, or is heavier, than fat. You will find most professional athletes don’t bother with BMI because they are overweight. BMI is calculated based on the height and weight of a person. The formula is (weight(lbs)/height²(inches))x703, where 703 is a conversion factor using english measurement. For example, a 150lb woman who is 5’5″ (or 65 inches) has a BMI of 24.98. According to the BMI chart system a BMI of 24.98 is borderline normal and overweight. Second thing to know is that women tend to carry more fat than men. Period.

Back to the reason why I may have had a higher BMI than my white girl counterpart. My muscle mass may have been more dense, thus weighing more. I didn’t come across a particular study to prove or disprove this (doesn’t mean it doesn’t exist), but when you look at female track athletes there is a “classic” body shape that generally emerges. The thighs become very developed and the lower legs are skinnier. The muscles in the thighs and back are the largest thus accounting for the most lean mass. I had thick thigh muscles for sprinting. So I may have outweighed my counterpart in that regard. 

Another possibility to consider is bone weight. There has been research into whether the bone weight/density between races differs. There are so many articles on this it’s hard to determine the definitive answer. In 2000 The Journal of Clinical Nutrition published an article that black people have heavier or more dense bones than their white counterparts. So, my bones have been heavier. My skeletal frame may have been “bigger”. There are some women (regardless of race) who have a petite frame or fine features; others are built like “brick houses” if I can borrow from the Commodores.

Here are some metrics to use when looking at your current and future states:

  • % of body fat – there are way to measure your ratio of fat versus lean mass
  • Measuring tape – whip out the measuring tape and look at the inches around your middle, arms, thighs, chest, etc.
  • Old school calipers – a device used to pinch the fat under your arm to get a sense for how much fat you’re carrying

There is no one-size-fits-all when it comes to using physical characteristics to determine your weight profile. Though I didn’t get into this much, there are important internal factors that determine your health profile. The new black chick finds the method that’s best for her and sticks with it.

I’m just keeping new.


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