BMI – Body Mass Index as a Ruler of Health

The Body Mass Index is a measure based on height and weight, and arguably not based on determining the health of an individual. While many kids and adults use the system to determine their health, based on the assumption that fat relates to health, there’s a lot of problems with BMI as a health indicator. Beauty Redefined  has a great post covering all the various issues with BMI. Check it out here.

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I’m currently taking a social science statistics course in university and we talk a lot about measurement. What does it mean when we measure a particular thing? How do we go about it? What do we learn from the result? These are important questions. When we’re trying to define health with BMI, there’s a lot of poor answers to these questions.

First, does measuring the fat in your body measure your health? We use the BMI as a measure of health often in public discourse. If determining health is the purpose of the Body Mass Index, does it do this? While public sentiment would say,”yes,” the scientific community has not yet determined a solid answer. A lot of people are convinced that fat is a huge factor of health, and some scientists are convinced that fat is not as closely linked to total health as we’ve been led to believe. So, it’s not settled whether being 20 pounds ‘overweight’ makes you significantly less healthy and at risk of many diseases. How much weight means how much less healthy? We’re not totally sure yet. (more info in the link above).

Second, if fat is the factor of health to measure, are we even measuring fat when we use the BMI? Well… unfortunately, we’re not. By using the height and weight, we’re not entirely sure what we’re measuring. How much of your weight is muscle? How much is fat? What about people with different body frames? It’s a test that’s very easy to use, but doesn’t effectively measure what it indicates. Other options, like waist circumference, have been suggested as alternatives that better estimate our body composition.

How we count matters when we’re measuring health. Think inches versus centimeters. If you’re measured in inches – 2.5 cm each – you will be fewer inches tall than you are centimeters tall. Is that because you’re shorter when measured in inches? Of course not, but knowing that we’re measuring in inches, not centimeters, is very important. When we measure health, we need to know whether we’re measuring correctly. Using the BMI system is not the most accurate way to determine the health risks that we have, and if health is what we’re after – not just more skinny people –  then we need to start counting differently.