Why BMI is BS: Health Experts Weigh In

BMI, or Body Mass Index, is a common, yet flawed measure that is used to determine an individuals overall health. While this tool can be useful in research and screening, it is prone to various inaccuracies and limitations in assessment.

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 is 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 the two criteria listed does not take into account the complexity of the human body. Crucial factors that are not considered when using BMI are muscle mass, bone density, and distribution of fat.

Strictly Height to Weight Ratio 

Research shows that using BMI alone isn’t an accurate measure of a person’s health. Many active individuals can be at an “ideal” weight for their height, but aren’t necessarily considered healthy. They could be dealing with imbalances with other health indicators such as cholesterol, hormone balance, lipid profile, blood sugars, etc.

BMI can lead to misclassification of an individual’s true health status as 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.

Why is BMI Still Being Used?

Despite its limitations, BMI is used in healthcare for several reasons:

  1. 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.
  2. Widespread use: BMI has been used for over a century and became a standard measure of body weight in healthcare. This widespread use has made it a well-established and widely recognized tool.
  3. Convenience:  BMI provides a convenient way to categorize individuals into broad weight categories (underweight, normal weight, overweight, and obese). 
  4. Lack of Alternatives: While there are more accurate measures of body composition, such as skin fold 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:

  1. Waist circumference: This measures the amount of abdominal fat which is a strong predictor of health problems associated with excess body weight.
  2. 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.
  3. Lipid profile: This measures levels of cholesterol and triglycerides in the blood, which are important indicators of heart health.
  4. Blood pressure: High blood pressure is a risk factor for heart disease and stroke.
  5. Glucose and insulin levels: These measures can help to identify individuals who are at risk for diabetes.

How we can help

It is best to meet with a specialized health professional (i.e., Registered Dietitian) to assess nutritional status 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. 

Schedule an appointment with one of our Registered Dietitian Nutritionists (RDNs) at one of our locations in Arizona, Pennsylvania, or virtually. We are excited to help get you started on your health and wellness journey. We promise…no BMI, and no BS!