The surprising health threat your BMI reveals
At some point in your life, you’ve probably figured out your body mass index (BMI). It’s a calculation that’s supposed to tell you if you’re overweight. But the jury’s still out on what this number really tells you about your weight or your health.
It’s calculated by dividing your weight in kilograms by your height in meters. And some people say it can help determine your risk of diseases like type 2 diabetes, heart disease and cancer.
But BMI doesn’t consider a few important factors, like how much muscle you have or where you hold your extra fat. That means people with a lot of muscle end up with a high BMI. And people who hold extra weight in their stomach could end up with the same BMI as people who hold extra weight in their hips—even though their disease risk is far greater.
So your BMI probably isn’t telling you the whole story. But despite its faults, the latest research suggests BMI can still tell you one important thing… the future of your brain health.
Researchers from the University of Arizona found connection between high BMI and poor cognitive functioning in older adults. They analyzed a 12 year study, looking at data from more than 21,000 adults over the age of 50. And adults with a high BMI ended up with worse brain health than those with a low BMI.
Why? Researchers say it all came down to inflammation. People with a high body mass index had more of it. And you know what inflammation does to your body. It turns it into a breeding ground for pretty much all diseases, including dementia.
Researchers found that the people with the highest BMI at the beginning of the study had greater changes in their C-reactive protein (CRP) levels over the following four years. CRP levels are a marker used to gauge how much inflammation you have throughout your body.
The change in CRP levels led to a measurable decline in brain health six years after the study started. Basically, researchers found that high BMI causes a chain reaction. The more your BMI goes up, the more your inflammation levels go up and the more your cognitive function goes down.
So even though BMI isn’t the be-all and end-all indicator of good health, it can still provide you with some idea of what’s going on in your body. And if you’re aware of its weaknesses that’s even better, because you can factor those in for yourself. Some of the most important factors to consider in addition to your BMI are your:
- Family history
- Physical activity levels
- Muscle composition
- Fat distribution (belly fat vs. lower body fat)
Of course, if you want a more thorough picture of your health, you could also go to a health clinic that has a DEXA scanner. It scans your body and tells you how much muscle, bone and fat you have. It’s the most accurate reading of body composition available.
But be warned… you can’t hide anything from the DEXA scanner. It even finds the fat hiding in your muscles, so you’ll probably come out with a higher fat composition reading than if you calculated your body mass index the old fashioned way with a pen and paper.
Kyle Bourassa et al, Body mass and cognitive decline are indirectly associated via inflammation among aging adults, Brain, Behavior, and Immunity (2016).
“Body Mass Index.” The Center for Disease Control and Prevention. https://www.cdc.gov. Retrieved October 19, 2016.