Sometime during your last doctor’s visit, your physician probably had you hop on the scale.
After weighing and measuring you, she might have shown you a colourful chart like this one:
Based on your measurements, she may have told you, you wanted to be “in the green,” meaning you were considered a healthy weight based on your height. If your measurements landed you in a blue square, on the other hand, you were likely underweight, while landing in a yellow, orange, or red square meant you were likely overweight.
But guess what? This rough calculation, also called a BMI or body mass index, is actually not a great measure of fitness when used on its own.
Turns out the BMI was invented in the 1830s, and, as with many things that have been around for nearly 200 years, it seems to have outgrown its utility.
There are four big problems with BMI, according to obesity experts:
- It doesn’t give you a good estimate of how much body fat you’re carrying around.
- It can differ drastically based solely on your gender. A man and a woman with an identical body fat percentage could have widely different BMIs, for example.
- Just because you have a high BMI doesn’t necessarily mean you’re overweight. You can have a high BMI even if you have very little body fat, especially if you’re male and very muscular.
- It doesn’t take into account your waist circumference, which can be a good measure of your risk for certain diseases including heart disease and type 2 diabetes.
So if BMI isn’t the best way to tell if you’re a healthy weight, what is?
Several tools — including a regular doctor’s visit — can help you ensure your weight isn’t putting you at risk of serious health problems ranging from stroke to heart disease and diabetes.
One of the best measures involves measuring the circumference of your waist. Having excess body fat — especially around your middle — has been strongly linked with specific health problems, including type 2 diabetes.
In a large 2012 study, researchers looked at data from more than 340,000 people from eight European countries. They found that overweight people with large waists (more than 34.5 inches or 88 cm for women and more than 40 inches or 102 cm for men) were at a similar risk of developing diabetes as people who were clinically obese. The link was the strongest in female participants.
Another measure includes calculating your body fat percentage, but this can be a bit tricky to do at home. In the US, personal trainers frequently use the skinfold method, which involves measure the percentage of fat in various folds of skin on the body using a skinfold calipers, to give you a rough estimate of your body fat percentage.
Still, some experts say we shouldn’t write off BMI entirely, because it can give public health experts a rough look at how whole populations are doing weight-wise. And when it is combined with other measurements like waist circumference, it can help give people a peek into their weight-related health.
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