BMI? I prefer RFM

Over the past few years, you may have heard that a person’s weight or BMI doesn’t mean a person is unhealthy. Welcome to the “obesity paradox” and why health assessment isn’t so black and white.

According to an article published in Annals of Internal Medicine, along with other recent studies, there is an association between mild obesity and a lower mortality risk.

BMI is a measure of one’s weight in relation to their height and is only a risk factor (depending on the number, it may be considered multiple risk factors) for additional health issues and mortality. BMI does not accurately measure body composition such as bone density, muscle mass, or body fat.

The findings from the article above indicate that body fat alone, not weight or BMI, was independently associated with higher mortality.

Another recent study indicates a potential equation that could be used instead of BMI to better estimate risk factors as it looks at body fat percentage. The equations provided were tested against gold standard devices and according to the abstract “was more accurate than BMI to estimate whole-body fat percentage among women and men and improved body fat-defined obesity misclassification”. We're referring to Relative Fat Mass or RFM.

There are other devices available that help measure body composition, of course. I've seen BIA scales at Target. Some gyms offer the hand-held versions. Unfortunately, these are not very accurate compared to more expensive devices some health professionals can afford to purchase. A BIA scale in which you step on measures your lower half and the hand held measure your upper half, typically; you're only getting a glimpse into a portion of your body composition and it probably isn't as accurate as you think. That doesn't mean they are all bad- I'm a fan of the InBody products in which you are holding onto a bar and standing on a scale for a full body assessment, for example.

So, let’s take a step back and consider that it is more likely a higher body fat percentage than actual weight or BMI that puts us at higher health risks. If so, perhaps we can throw terms like obesity out the window and focus more on an individual’s health behaviors, genetics, environment, and body composition?