BMI vs. Body Fat: What's More Important?

We’ll start at the very beginning: Body mass index (BMI) is a measure of someone’s weight compared to their height whereas body fat percentage is a measure of how much body fat someone has relative to their overall body weight.

They’re both ways of assessing whether someone has a healthy weight, excess weight or obesity. But, if we’re comparing the two, body fat percentage has some clear advantages.

BMI can be an inaccurate health indicator for certain people and high body fat — especially around the stomach — is linked to health conditions, even if you have a healthy BMI.

Below, we dig into the difference between BMI vs. body fat percentage, including the pros and cons for each, how they’re calculated and what healthy ranges look like.

BMI and body fat percentage are both ways of determining whether a person has a healthy weight or not. A high BMI can indicate a high body fat percentage, but it’s not quite 1:1.

Here’s the inside scoop.

BMI

BMI measures a person’s weight compared to their height. It’s a simple division equation.

Since it’s such a quick and easy way to get a rough idea of whether you have a healthy weight, excess weight or obesity, healthcare providers sometimes use BMI as a screening tool.

Discover your BMI with the Hers BMI Calculator.

If you have a high BMI, they may do further assessments, such as checking your body fat percentage or asking about your family history and eating and exercise habits to determine if you’re at risk for weight-related health conditions.

But BMI isn’t an accurate indicator for everyone.

For example, if you’re an athlete or bodybuilder with a lot of muscle, you may weigh a lot relative to your height, but that weight isn’t necessarily fat — it would be made up of a lot of muscle too.

BMI also doesn’t account for certain biological differences between men and women.

It isn’t always helpful for diagnosing abdominal obesity, or obesity around the center of the body, either. And abdominal obesity is linked with many adverse health conditions, including type 2 diabetes, high blood pressure and heart disease.

In short? BMI can be a good starting point, but it’s not the be-all, end-all.

Body Fat Percentage

Body fat percentage is a measure of how much body fat you have in relation to your overall weight. It can be more accurate than BMI at assessing whether someone has a healthy weight and whether they’re at risk for certain health conditions.

For example, research shows that higher visceral fat — fat that’s found deep within the abdomen around your organs — is associated with cardiometabolic risk and coronary artery calcification regardless of BMI.

Body fat percentage measurements might be able to pick up on these risks that BMI measurements might not.

You can calculate how much body fat you have in a few ways — such as with skinfold measurements, waist circumference measurements or a dual-energy X-ray absorptiometry (DEXA) scan.

Research shows that methods of determining body fat that consider waist circumference may be better than BMI at evaluating metabolic and cardiovascular risk.

But while body fat may seem more useful than BMI, there’s no simple formula to work it out. Tests may be expensive, not readily available and require a trained healthcare professional.

BMI vs. Body Fat: What to Focus On

BMI and body fat are linked, but not as closely as you might think.

You can have a high BMI, but a healthy body fat percentage — think back to those athletes and bodybuilders. But you can also have a healthy BMI and an unhealthy body fat percentage.

A 2023 study on 3,001 participants found that almost 1,000 of them had healthy BMIs with body fat percentages ranging from four percent to 49 percent.

In this group, 26 percent of men and 38 percent of women had excess body fat.

Despite having a healthy BMI, they had:

• Higher triglycerides (a type of fat found in your blood)

• Elevated low-density lipoprotein (aka “bad cholesterol”)

The men also had elevated total cholesterol.

Beyond this, 60 percent of the women in this group had an abdominal circumference of almost 35 inches or more, which could increase their risk of developing certain health conditions.

So, just looking at BMI here wouldn’t be an accurate indication of their health.

What’s more, two people with the same BMI can have different body fat percentages.

Women tend to have more body fat than men, even if they have the same BMI. Body fat can also differ between races, ethnicities and ages — older folks tend to have more body fat than younger adults.

These factors aren’t reflected in BMI.

So, what’s more important: BMI or body fat? Both are important measures of health, but body fat — and whether you store it around your middle — may be more helpful in determining whether you have a healthy weight or a higher risk for certain health problems.

If you’re looking to move towards a healthy weight, here are some tips to keep in mind:

• Eat nutritious whole foods and plenty of protein

• Incorporate more movement into your day — walking is linked to lower visceral fat and BMI, so upping your steps can help

• Try to drink about eight glasses of water each day

• Get sufficient sleep

To calculate BMI, divide a person’s weight in kilograms by their height in meters squared.

Translated into imperial, that’s a person’s weight in pounds divided by their height in inches squared, multiplied by 703.

So, BMI = lbs/in² x 703

If you weigh 160 pounds and you’re 5 foot 6 inches (66 inches), that would be 160 / 66² x 703, which equals 25.8.

Check out our guide to BMI to learn more.

Anywhere between 18.5 and 24.9 is considered a healthy BMI.

In total, there are four BMI ranges and categories that apply to all adults — both men and women — aged 20 and older:

But remember, BMI isn’t the full picture. It’s not an accurate health indicator for everyone and it doesn’t necessarily indicate whether you have a healthy or unhealthy amount of body fat.

Think of it more like a starting point that can help you figure out whether you have a healthy weight.

Body fat percentage is a little more complicated to work out than BMI.

You’ll probably have to visit a healthcare provider to find out your body fat percentage.

Here are a few different ways they might calculate your body fat percentage:

• Anthropometry. This includes waist circumference, waist-to-hip ratio and skinfold measurements — the last of which requires measuring the width of your skin and the body fat underneath it in places like your triceps using calipers.

• DEXA scans. An X-ray of your entire body can help a healthcare provider work out your body composition, or how much of your body is made up of fat, muscle and bone.

• Bioelectrical impedance analysis (BIA). Muscle and fat conduct electricity differently, so this test uses electrical conduction to determine how much body fat you have.

• Air displacement plethysmography (ADP). This test involves sitting inside a special chamber known as a “Bod Pod” for about five to eight minutes. The air volume before you get inside the chamber is compared to the air volume once you’re inside to determine bone density, body fat and muscle mass.

Check out our guide to understanding body fat percentage to learn more.

Unlike BMI where there are agreed-upon ranges, there isn’t one set “healthy” body fat percentage.

In general, a body fat percentage of 35 or more is considered a sign of obesity in women. It’s 25 percent or more for men.

But a healthy body fat percentage will be different for everyone. You can speak to a healthcare provider to find out what a healthy range would look like for you.

Body fat and BMI are both important indicators of health, but they’re not equal.

Here’s a recap:

• BMI compares your weight to your height. It’s an easy calculation you can do at home to get an idea of whether you have a healthy weight, excess weight or obesity. But BMI tends to overestimate body fat in people with a lot of muscle and it doesn’t show how much abdominal fat you have, which is a risk factor for health issues like cardiovascular disease.

• Body fat percentage is a measure of body fat relative to your overall weight. It’s usually a much better indication of whether you have a healthy weight or are at risk of health issues. The catch? Body fat percentage tests can be expensive, difficult to find and require a healthcare professional.

• Speak with a healthcare provider to find out what’s healthy for you. You could have a healthy BMI, but an unhealthy body fat percentage or a healthy body fat percentage, but an unhealthy BMI. Your best bet is to speak with a healthcare provider to find out what a healthy BMI and body fat percentage would be for you.

If you’re looking into moving towards a healthy BMI or body fat percentage, remember to focus on eating nutritious foods and healthy snacks, incorporating more walking and movement into your day, drinking more water and getting enough shut-eye.

For some, weight loss medication can help you reach your goals.

Learn more about weight loss treatments from Hers.