The BMI is useless – here’s what you really need to know

Body mass index … the BMI … is completely useless.

It can’t even tell you if you’re overweight. Just look at professional athletes. Most have high BMIs but they are certainly not obese. They weigh more because of muscle, and the BMI can’t measure that because it doesn’t take into account body composition.

The BMI is even more useless when it comes to determining potentially serious health risks.

Here’s the latest proof the BMI is worthless: Researchers have found that you are at more risk for disease and early death if you have normal BMI but a high waist-to-hip ratio – especially death from a cardiovascular disease – than if you have a higher than “normal” BMI.

In a new study published online at the Annals of Internal Medicine, an international team of medical researchers looked at what is called “central obesity.” That’s a fancy medical term for having belly fat, which is different than having heavy legs or hips.

They looked at over 15,000 people who had their BMI and waist and hip measurements taken in a national health survey. Then they tracked the people’s health for over 14 years.

They found that even if you have a normal overall weight, if you have central obesity, men are 87 percent more likely to die early than with any other combination of BMI and waist-to-hip ratio, and women have a 48 percent higher mortality risk.

So you can have a high BMI, and still be better off than those who have excess around the middle but normal BMI.

And if you do have belly fat, you are much more prone to heart disease, especially women.

The real trick to avoiding disease and early death from excess fat is to know your body composition.

You want to know your waist-to-hip ratio. And you can use traditional calipers to measure body fat by looking at your hips (love handles) and upper arms.

But a better way to find your body composition is to go to a clinic with a DEXA machine. These were originally used to measure bone density. But many integrative medicine specialist use them to help their patients who want to drop weight know their body composition.

There’s nothing scary about it at all. You simply lie flat on the table-like scanner, fully clothed. A small dose of radiation passes through the body allowing X-rays to distinguish fat from muscle from bone.

One thing to note is that the DEXA scanner is so accurate at reading intramuscular fat than your body fat percentage will be a little higher – maybe 5 percent – than measuring by any other method.