Does your body mass index (BMI) really matter?

There are many reasons a healthcare provider takes your height and weight at your annual checkup—one of them being so they can calculate your body mass index (BMI). What exactly is BMI though? And does the number really matter?

What is BMI?

Your BMI is a measurement of your height-to-weight ratio (e.g., the taller you are, the more you're expected to weigh). Everyone's BMI falls somewhere on a scale, which classifies their measurement as underweight, healthy or a level of obesity. So, what is a healthy BMI?

Here are the body mass index (BMI) categories for adults:

• Underweight: BMI under 18.5
• Healthy: BMI between 18.5-24.9
• Overweight: BMI between 25-29.9
• Obesity: BMI of 30 or more

How can I calculate my BMI?

One of the easiest ways to figure out your BMI is by using the CDC's free adult BMI calculator.

After entering your height and weight, the calculator will quickly provide your BMI value and tell you which category you fall into. This can be a helpful starting point for understanding your body composition and overall health.

However, it's important to remember that BMI is just one tool among many. It doesn't take into account factors like muscle mass, bone density or distribution of fat.

Is BMI an accurate assessment of my health?

Yes and no. BMI is a useful tool for healthcare providers to quickly identify health risks. For example, a person with a high BMI has a greater chance of developing cardiovascular disease and diabetes—but your BMI alone doesn't provide a detailed picture of your health. Regardless of your BMI, it's more important that your provider knows about lifestyle factors and family history that could affect your health.

"Making sure you're getting enough activity, staying away from nicotine, engaging in regular physical activity and eating a good balanced diet are better indicators of your overall health than your BMI alone." —Laura Birkel, Gundersen Registered Dietitian (RD)

It's also worth noting that your BMI does not always accurately depict your specific body composition, such as how much fat versus muscle you have. You may increase your physical activity and find that your clothes begin to fit differently, but your weight or BMI remains unaffected. This is because the composition of your body is changing (you're gaining muscle, losing fat).

OK. So why does my BMI matter then?

Knowing your BMI can help your healthcare team better understand what care options are available to you. This is especially true if your BMI is greater than 30 and you want to improve your health. For example, if you are interested in taking weight-loss-aiding medicines or trying a medically supervised meal-replacement program, you must have a BMI greater than 30. For bariatric surgery, your BMI needs to be above 40, with some exceptions for those with a BMI between 30 and 40.

"BMI is a baseline measurement to help dictate where we go in terms of what kind of plan or program is most appropriate for a patient," Birkel says. "The number is not meant to define someone's health. It's meant to guide their care where it needs to go."

Key factors to consider when evaluating BMI

It's important to remember that BMI is just one piece of the puzzle. For example, athletes may have a high BMI due to increased muscle mass, but they can still be very healthy. Therefore, it's crucial to have a comprehensive discussion with your healthcare provider about your individual situation.

If your BMI indicates that you may benefit from weight management strategies, your healthcare team can help you explore various options. These may include lifestyle changes, such as adopting a healthier diet and increasing physical activity, or more structured programs that provide additional support.

Ultimately, the goal is to create a personalized plan that fits your needs and preferences. This approach not only helps you achieve a healthier weight but also promotes long-term well-being.