Doctors often use BMI, or Body Mass Index, to quickly screen patients for more tests. But having a normal or low BMI doesn't mean you're healthy, and having a high BMI mean you're unhealthy. To help your doctor better assess your overall health, measure your waist size too. Here's how.
Image by Jamiesrabbits.
A big waist size matters because, even if you're not overweight or have a low BMI, it could indicate you have more fat stored around your abdominals, so-called "abdominal obesity". It's closely associated with a higher risk of obesity-related health issues, even after taking BMI into account. Men especially tend to store more fat in their abdominals.
According to the Centres for Disease Control and Prevention, here are the guidelines that put you at higher risk of obesity-related conditions:
- A man whose waist circumference is more than 102cm
- A non-pregnant woman whose waist circumference is more than 89cm
To find out your waist circumference, use a measuring tape (get it from a drug or fabric store) and wrap it around your belly button. Consider taking these measurements first thing in the morning, after using the bathroom, and without a shirt on to keep measurements as accurate as possible. Your hydration levels, whether you've eaten and even your menstrual cycle (if you're a lady) could influence measurements. Make sure that the tape is horizontal across your waist and that it's not pulling tightly on your skin.
Some say measuring waist-to-hip ratio is better, but Harvard School of Public Health Obesity Prevention Source noted their research showed that waist size alone and waist-to-hip ratio measurements were both equally effective. In this instance, waist size is simply more practical and easier for most people.
Here's the thing: Both your waist size and BMI are just screening tools and both can't very well differentiate muscle from fat. You still need your doctor to draw clearer conclusions about your health.
Assessing Your Weight [Centres for Disease Control and Prevention]