BMI, or Body Mass Index, is an all-too-common yet flawed number that’s used to determine a person’s health. And while the tool can be useful in research and screening certain populations, it’s prone to inaccuracies when used to rate healthy individuals who exercise regularly.
Our Bodies are More than a Category
We know our bodies are more than a category. Health is complicated. BMI is a simple height to weight ratio that can be calculated by dividing your weight in kilograms by your height in meters squared. The criteria for determining if a person is underweight, normal (healthy weight), overweight or obese are as follows:
Underweight: < 18.5 kg/m2
Normal: 18.5 – < 25 kg/m2
Overweight: 25 – < 30 kg/m2
Obese: > 30 kg/m2
To assume health based upon two criteria, height and weight, does not take into account the complexity of the human body. Some people have a high BMI and are fit, while other people have a low BMI but are unfit.
Strictly Height to Weight Ratio
Research show that the BMI alone isn’t an accurate measure of a person’s health. Many athletes and other highly active individuals are at an “ideal” weight for their height, but aren’t necessarily healthy based on other health indicators such as cholesterol, hormone balance, lipid profile, blood sugars, etc.
BMI can also lead to misclassification of an individual’s true health status because it does not take into account the distribution of body fat. For example: a person with high muscle mass and low body fat may be classified as overweight or obese based on their BMI, while a person with a lower muscle mass and higher body fat may be classified as normal weight. This is because muscle weighs more than fat.
So Why is it Still Being Used?
Despite its limitations, BMI continues to be used in healthcare for several reasons.
- Simplicity: BMI is a simple and easily calculated measure that requires only two measurements, height and weight. This makes it accessible and cost-effective, especially in resource-limited settings.
- Widespread use: BMI has been used for over a century and has become a standard measure of body weight in healthcare. This widespread use has made it a well-established and widely recognized tool.
- Convenience: BMI provides a convenient way to categorize individuals into broad weight categories, such as underweight, normal weight, overweight, and obese.
- Lack of Alternatives: While there are more accurate measures of body composition, such as skinfold thickness, bioelectrical impedance, and dual-energy x-ray absorptiometry (DXA), these methods are often more expensive, time-consuming, and require specialized equipment.
Better Indicators of Health
There are several other indicators that encompass a more accurate representation of health other than BMI:
- Waist circumference: This measures the amount of abdominal fat, which is a strong predictor of health problems associated with excess body weight.
- Body composition: Measures such as skinfold thickness, bioelectrical impedance, and dual-energy x-ray absorptiometry (DXA) can provide a more accurate assessment of body fat and muscle mass.
- Lipid profile: This measures levels of cholesterol and triglycerides in the blood, which are important indicators of heart health.
- Blood pressure: High blood pressure is a risk factor for heart disease and stroke.
- Glucose and insulin levels: These measures can help to identify individuals who are at risk for diabetes.
It’s best to meet with a specialized health professional (i.e., a Registered Dietitian) to assess nutritional status and other biomarkers, to gain a true understanding of your overall health. Having the support of professionals is key to making informed decisions and devising a treatment plan that is best suited to your unique needs.
Meet with a Registered Dietitian to get started on your health and wellness journey. We promise…no BMI, and no BS!