Why BMI is BS
Our cultural fear of fatness heavily influences how we measure health. It might shock you, but weight isn’t necessarily a predictor of poor health.
You are likely familiar with the term BMI and have seen or been told which category your body falls into; under weight (>18.5), normal weight (18.5-24.5), over weight (25-29.9) or obese (30+).
BMl, body mass index, is a simple calculation that expresses the relationship between your height and weight as a single number. Some studies suggest that a high BMI can also be an indicator of high body fat and therefore can be used to screen for certain weight levels that could lead to health problems like diabetes and heart disease. Although this may be true for some, it is not a true diagnostic of body fatness or of an individual's overall health.
BMI is not a true diagnostic of body fatness because it doesn’t take into consideration; body composition, age, gender or race and ethnicity.
Body Composition-BMI can’t tell what percentage of a person’s weight is from their fat, muscle or bone. Since bone weighs more than muscle and muscle weighs more than fat, people with more muscle mass will naturally have higher BMIs.
Age- As we age, our body composition changes. We tend to lose muscle and bone mass and increase fat storage in the abdominal region.
Gender - BMI was developed and validated mostly in white men. Additionally, a woman tends to have more body fat than a man with the same BMI.
Race and Ethnicity - More and more research shows that there are biological and genetic differences in the relationship between weight, muscle mass and disease risk among different groups of people. Some studies have found that black women had less metabolic risk at higher BMIs than white women. 1 Asian or Middle Eastern descent have a higher risk for metabolic diseases like diabetes at a lower BMI than people of European descent. 2
Determining someone’s overall health status is complex. Health is influenced by many factors, which may generally be organized into five broad categories known as determinants of health: genetics, behavior, environmental and physical influences, medical care and social factors.
BMI can be a piece of the health puzzle but by no means should it define you. In our practice, too often we see clients who have felt judged, shamed and stigmatized as not being “normal weight” and thus “not healthy”. According to a recent New York Times article, only a quarter of adults in the United States can call themselves “normal” based on their BMI. 3 Unfortunately, these labels often result in extreme behaviors to lose weight and or prevent some patients from seeking medical attention which ironically results in poor health.
What’s “normal” to a person's unique genetic makeup varies person to person. Not only that, our weight is going to look different at different stages in our life based on those determinants of health. We believe whatever weight a person reaches when they’re living the healthiest life they can actually enjoy no matter where it lands on the BMI chart is likely the right weight for you!