What Does BMI Really Tell Us
Although I’ve never been a great fan of Body Mass Index (BMI) to assess quality of life, I find it interesting that something so many people have relied on for evaluation of health and longevity is now being questioned. Perhaps BMI will go the way of the scale and we’ll be left determining how we’re doing taking care of our bodies by more valid health measurements. But don’t hold your breath for that to happen.
BMI is the measurement of a person’s weight in relation to their height. According to “Body mass index flawed as a measure of obesity” by Jane Brody (Sarasota Herald-Tribune, 4/22/14, 41E), the index, developed between 1830-1850, was later adopted by insurers as a way to assess weight in large populations. Brody points out that BMI was not developed for doing individual assessments of health and longevity, but it became the gold standard anyway. Gotta wonder how that happened, huh?
There are several problems with BMI assessment. First, it doesn’t measure internal body fat which is the culprit for disease and premature death. Because of this, people with normal BMIs can still have more internal body fat than is considered healthy. Second, BMI doesn’t measure the distribution of body fat which is a better predictor of being prone to certain diseases. Significant abdominal fat is metabolically active and more likely to cause unhealthy conditions than fat on the hips, buttocks, or thighs which is more “metabolically inert.” Third, maintains Brody, “a person’s age, gender and ethnicity influence the relationship between BMI, body fat and health risk.” Also, women have a higher percentage of body fat than do men, but this does not make them more disease prone. Fourth, physical fitness must be factored in when considering health risks. Remember, you can be fat and fit or thin or normal weight and still unfit.
Genetics aside, it seems to me that if we really want to be healthy, we don’t need to keep hopping on the scale or grabbing our calipers to measure our BMI. We can have blood work done to evaluate our cholesterol and triglyceride numbers and have our aerobic capacity and bone strength tested. But we can’t rely on even those numbers to tell us if we’re fit or healthy. What we can do to move toward health and longevity you already know how to do: eat mostly nutritious foods, drink plenty of water, get enough sleep, reduce stress and improve at handling it, stop smoking, don’t overdo it with alcohol, have strong connections with others, and go out there and find pleasure and meaning in life. When you’re doing all of the above, you don’t need to know your weight or BMI because you’re living the most healthy lifestyle you possibly can.