A Dietitian’s take on BMI & Understanding WHat BMI really Means
Have you ever been told to try to achieve a “healthy” BMI? We hear about BMI frequently, including BMI categories of underweight, normal weight, overweight, and obesity. But what does that really indicate for our health? There are limitations to BMI to consider:
BMI Factors To Consider
- BMI Only Uses Height & Weight
- BMI is a Poor Measurement of Body Fat
- BMI Does Not Consider Genetics
- BMI Does Not Consider Age
- BMI Does Not Indicate Overall Health
1. BMI Only Uses Height & Weight Measurements: BMI is calculated based on only two measures: weight and height. BMI was developed in the 1800s by a mathematician as a way to categorize individuals and compare weight to height ratio. It was not until later that BMI was used to assign health risks.
2. BMI is a Poor Measurement of Body Fat: BMI is a poor measure of body fat. Since it only takes into account your total weight in the context of your height, it does not differentiate between muscle and fat mass, or where that weight is distributed on your body. For example, a bodybuilder with minimal fat mass may be considered obese based on BMI.
3. BMI Does Not Consider Genetics: BMI-related health risks are not universal between ethnicities. For example, The World Health Organization proposes the current BMI cutoff of >25 being considered overweight should be lowered to a BMI of 23 for Asian populations. This is due to the genetic predisposition of Asians to store more body fat around the waist, which increases heart disease risk.
4. BMI Does Not Consider Age: An overweight BMI is actually protective for adults over 65 years old. A meta-analysis of older adults found that a BMI less than 23 (considered a “normal” BMI) is associated with increased mortality in this population.
5. BMI Does Not Indicate Overall Health: BMI should not be the only measurement of your health. Overall health is not based on a single factor such as weight, and a well-informed health provider should also take into account bloodwork, lifestyle, family history, physical fitness, and several other factors to determine your health status.
Summary:
Some takeaways to consider include challenging the thought that at a BMI of 24.9, you are considered healthy, but at a BMI of 25.0, you are considered overweight or unhealthy. BMI is a quick, simple, minimally invasive measure used in health assessments, but should always be taken into consideration with body composition, personal weight history, genetic predispositions, and other factors.
Lydia Averette
MS, RD, LDN
Lydia is a Licensed and Registered Dietitian Nutritionist who enjoys counseling clients with diverse backgrounds. She obtained her B.S. in Nutrition Sciences at NC State University with a Minor in Sports Science and her M.S.