Why BMI is a Terrible Health Metric – What Are the Alternatives
October 10, 2022BMI – this little numerical label can be found all over gyms, doctor’s offices, and health books. Haven’t seen it? Just look on the side of the treadmill next time you work out. Though it was designed to be a quick and easy way to calculate weight relative to height, BMI – short for Body Mass Index – isn’t as telling as it claims to be and may not be as effective and actually a terrible health metric.
What is BMI Good For?
BMI is a simple chart and calculation method that allows you to place yourself within a designated range: underweight, healthy weight, overweight, obese. Developed in the 1830s – before everyone had calculators and digital tools at their disposal – BMI consists of an easy, straightforward formula.
BMI = weight in kilograms divided by height in meters squared.
In general, a BMI that falls between 18.5 and 22 is considered ‘normal’ or healthy, while a BMI over 25 is considered overweight, and a BMI of 30+ is considered obese. BMI is often used as a screening tool to alert individuals to potential risks associated with weight. Of course, BMI was created with good intentions: to allow people to better understand and manage their health. The only problem? Well, it isn’t very accurate!
Underweight, Overweight, Obese – It’s Important to Know Where You Stand
BMI categories can be helpful in understanding if a person may have an elevated risk for all sorts of different health conditions. For example, research shows that a person with obesity has a higher risk of developing type 2 diabetes, heart disease, cancer, and sleep apnea.
Thus, knowing where you stand can provide a clearer picture of your health profile and your potential risks. For some, linking these BMI labels with certain risks can also provide a much stronger dose of motivation to drive forward in adopting a healthier lifestyle.
Two Major Flaws with BMI
Though weight is often a key component to assessing one’s health, BMI is far from being a flawless tool. In fact, BMI can be quite misleading and is terrible health metric in two very specific ways:
1.
BMI does not account for body shape
Pear-shaped, top-heavy, shorter torso – we come in all different shapes and sizes! Because the formula only includes weight and height, BMI alone doesn’t paint the whole picture. And as research shows, there is a closer link between diabetes and waist size than diabetes and overall body weight. So, while BMI shows us a relationship between our height and weight, it doesn’t account for the shape of our body and the distribution of that weight on our bodies.
2.
BMI does not distinguish between muscle/fat
It is well known that muscle weighs more than fat. And since BMI is a measurement based on our weight, it doesn’t account for whether or not that weight is muscle or fat. And someone who has a very high percentage of muscle contributing to their weight may see a much higher BMI, which can certainly cause confusion.
Better Ways to Understand Weight
BMI can be a helpful data point but it shouldn’t be used as an isolated measurement. Instead, it should always be used alongside other assessments for a more complete understanding of health. Also, it’s important to consider fat distribution throughout the body, as that can play a role in determining elevated health risks. So using BMI in combination with a body composition measurement will give the data more meaning.
Additionally, excess fat around the abdomen can put strain on important organs like the liver, heart, and kidneys. Comparatively, a little extra fat around the thighs or rear is typically not as concerning as fat around the waistline when it comes to cardiovascular health and the risk of developing diabetes. Thus, some doctors suggest another formula that’s easy to remember: a waist-to-height ratio. The general rule of thumb? Keep your waist circumference less than half your height to reduce the risk of developing diabetes and other conditions associated with obesity.
BMI can be a useful measurement but it shouldn’t be an isolated one. It is simply one data point that that can be a terrible health metric and doesn’t paint a full picture so make sure you are considering it that way!
Dr. Candice Seti, Psy.D., of Me Only Better is known in the community as "The Weight Loss Therapist."
 | ABOUT THE AUTHOR Dr. Candice Seti, Psy.D., of Me Only Better is known in the community as "The Weight Loss Therapist." Dr. Seti is renowned for her expertise in applying cognitive therapy to weight loss and weight management and extensive knowledge of nutrition and exercise applications to a weight management program. This is an area Dr. Seti has been passionate about for many years after her own weight loss experience. Read more articles by Dr. Seti! |
