This is a thick topic, so I’ll be breaking the discussion into three parts. Starting with part 1: BMI.
Body Mass Index (BMI) is a person’s weight in kilograms divided by the square of height in meters. A high BMI can be an indicator of high body fatness. BMI can be used to screen for weight categories that may lead to health problems but it is not diagnostic of the body fatness or health of an individual.
BMI is often used in the context of telling someone that they need to lose weight because they’re “not at a healthy weight.” Generally this happens in a medical context by a doctor, or some other form of official context where BMI is used to justify the advice: “lose weight.”
The immediate reaction to this sort of news can be visceral and negative.
“I exercise 3 days a week and feel great!”
“I’m not unhealthy! You can’t define ‘health’ with a height/weight chart!”
“How dare you tell me I need to lose weight when I walk all the time!”
The known-inaccuracy associated with BMI is in it’s application to trained athletes, not for people “who exercise.”
What does it take to be considered a “trained athlete?” I’ll use myself as an example, using both BMI and the reasons it is “inaccurate.” Results directly from the CDC’s BMI calculator.
Height: 6 feet, 3 inches
Weight: 205 pounds
Your BMI is 25.6, indicating your weight is in the Overweight category for adults of your height.
For your height, a normal weight range would be from 148 to 199 pounds
I can dismiss these results as inaccurate, but not because “I feel healthy” or because “I exercise regularly.” I dismiss them because I know my health statistics, down to the qualitative measurements of strength and quantitative bodyfat % numbers.
I have measured my bodyfat %, and it is sitting at roughly 13%. Being 13% bodyfat means that for my weight, 13% of it is fat, 87% is muscle. In order to achieve this ratio I do several things regularly with practiced care and precision:
- Power-lift with a proven program (5/3/1 + aesthetic accessories)
- LISS (low-intensity, steady-state) cardio for fat-loss on a regular schedule
- Control caloric intake based around my Total Daily Energy Expenditure (TDEE)
- Control macronutrient intake based around my Lean Body Mass (LBM)
That is what it means to be a “trained athlete.”
- Endurance athletes with progressive training schedules (runners, swimmers, etc.)
- Competitive sports athletes with regular practices (soccer, lacrosse, football, etc.)
- Weight-lifters with strength goals
These people have body-composition needs. They are also generally a higher percentage of muscle than fat. A normal person will likely have a body-fat % of 20-30%. Meaning someone who doesn’t train like me, but who has the same height/weight, will be weaker, less lean looking, and overall: less healthy.
The sobering reality that people need to acknowledge is that they’re not trained athletes, and the amount of exercise they’re doing doesn’t yield the sort of muscular frames that make BMI inaccurate. More likely: they’re overweight.
Admitting you’re overweight, or being told you’re overweight, is not a damning of your lifestyle or ability to be healthy. As the BMI definition stated: it’s an indicator.
It’s an indicator in the same way as someone warning you of a touchy conversation topic at dinner. If someone says “hey, I know you like to talk about [xyz], but you might want to dial it down tonight because [so and so] had a bad experience with it, and it hurts [his/her] feelings.” This warning isn’t someone saying you’re a boorish asshole, it’s a guideline that you can use to stay amiable.
A better reaction to indicators than revulsion and defensiveness is to instead consider: “how can I take this information and use it to make my life even better than it is.” Its an opportunity to re-examine what you know, learn more, and use that knowledge to become even happier than you claim to be now.
In part 2 I will address the Fat Acceptance/Health at Any Size movements on the basis of “can they be considered valid by the current scientific research.” Stay tuned!
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