The Accuracy of BMI Measurements

An unseen doctor takes her patient's weight measurements.

The body mass index (BMI) has long been used as a measurement method to determine a person’s health in relation to their weight. While it remains popular due to its relative ease of use, some have questioned the accuracy of this tool.

Is the BMI always an accurate representation of one’s health? What are the limitations of this popular tool? And if the BMI doesn’t work for me, are there other alternatives I can use to measure my body composition?

Learn the answers to these questions, and more, by reading this article.

What Is BMI?

The body mass index (often abbreviated to ‘BMI’) is a simple measurement tool used to categorize and assess people’s health based on their weight.

How to calculate BMI?

It is calculated by dividing a person’s weight in kilograms by the square of their height in meters (kg/m²). In other words:

BMI = weight (kg) / [height (m)]²

The calculation results in a number that quantifies the person’s health into one of four categories: underweight, normal weight, overweight and obese.

There are plenty of BMI calculator tools online that can help you do this calculation quickly. This includes TexomaCare’s very own BMI calculator.

Are BMI Scales Accurate?

The answer is complex. While the BMI is a simple and accessible tool, there are some factors that may influence the accuracy of one’s results.

Issues with the BMI include:

  • It does not account for muscle mass. The BMI does not recognize the difference between muscle and fat. For example, an athlete with a high muscle mass may be categorized as overweight by the BMI despite having a low body fat percentage.
  • It is not individualized. BMI measurements do not consider a variety of factors, including age, gender, bone density and fat distribution. This makes the tool prone to misclassification.
  • It does not account for waist circumference. Measuring waist circumference can provide more insight into health risks, particularly those associated with abdominal obesity. Even in people with a ‘normal’ BMI, an increased waist size may pose higher risk of heart disease or diabetes.

Overall, while this can be a quick and effective tool in providing an overview of one’s weight and health, its oversimplified nature may obscure the reality of one’s health. The BMI is good for a surface level snapshot of one’s health, but should not be used as a substitution for medical screenings.

What to Use Instead of BMI?

If you want to gain deeper insight into your health in relation to your weight, there are other tools and diagnostic methods that may give you a more accurate assessment of your body’s composition.

1. Body fat percentage

Body fat percentage is a measure of how much of your body is made up of fat. It includes both essential body fat (as in the fat we need for life and reproductive functions) and storage body fat. You can use tools like skinfold calipers, hydrostatic weighing, and bioelectrical impedance analysis to estimate your body fat percentage.

2. Waist-to-Hip Ratio

The waist-to-hip ratio, on the other hand, compares the circumference of the waist to that of the hips. It can indicate the distribution of body fat and is linked to the risk of cardiovascular disease.

3. Dual-Energy X-ray Absorptiometry (DXA)

DXA scans can provide detailed information about body composition, including bone density, fat mass, and muscle mass. Although not widely available for routine health assessments, it is considered a gold standard for body composition analysis.

4. Basal Metabolic Rate (BMR)

Understanding an individual’s BMR can help in assessing the amount of energy expended while at rest and can be used in conjunction with other metrics to gain a more comprehensive understanding of health.

Understand Your Health

While the BMI is a widely recognized tool for categorizing weight categories, it is not without its flaws. Its lack of precision in accounting for individual differences in individual body compositions make it an imperfect measure of health. While health professionals consider BMI in their health screenings, it is but one tool used in assessing health and other risk factors.

If you want to learn more about your health, TexomaCare is here to help.

Located in Denison, Texas, TexomaCare Weight Loss Surgery Center provides procedural options including gastric bypass surgery for people just like you looking for weight-loss solutions. Call us today at 903-416-6490 or take our health risk assessment to find out if weight-loss surgery is an option for you.


Individual results may vary. There are risks associated with any surgical procedure. Talk with your doctor about these risks to find out if bariatric surgery is right for you.

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