What would you say about a man who is 6’2 and 235 lbs? If you couldn’t see him, how could you assess whether or not he was at risk for obesity related illnesses? The obvious tool has been to calculate his Body Mass Index, or BMI. You can calculate this by dividing his weight (235 lbs) by his height in inches squared (5476) then multiply by 703 to get the BMI which in this case is 30.2. You can also use various reputable websites to get to the same figure by just inputting his height and weight. According to these websites, a BMI of 30 or greater is considered obese. Simple right?
What if I told you that this mystery man was Arnold Schwarzenegger at the peak of his bodybuilding career, would you still think he was obese? Probably not.
The problem with BMI is that it only considers height and weight, and fails to acknowledge body composition. Therefore when used solely as an obesity gauge, people with high muscle compositions may end up in the obese range while people with high fat, low muscle compositions may end up in the normal range.
Even though it is flawed, the BMI is still an important component to determining obesity and potential health risk. The National Institute of Health believes that combining BMI, your waist measurement in inches, and taking into consideration your current and genetic risk factors for obesity related diseases provides the best picture at your current and potential risk. More specifically, your risk for heart disease and type 2 diabetes increases in women with waist measurements of 35 inches or greater and men with waist measurements of 40 inches or greater. This is something a BMI clearly cannot determine.
Remember, the Body Mass Index is just a tool in the fight against obesity but it is not the only tool. You wouldn’t fix a house with just a hammer so why limit yourself to just one tool when looking to improve yourself?