When it comes to measuring your health and fitness, you’ve probably heard of both BMI (Body Mass Index) and body fat percentage. They’re commonly used to assess whether someone falls into a healthy weight range—but they’re not the same thing, and they don’t always tell the full story.

BMI is a quick calculation based on your height and weight. Body fat percentage, on the other hand, tells you how much of your body is made up of fat compared to everything else (muscle, bone, organs, etc.). While BMI is easy to measure and widely used, body fat percentage tends to be a more accurate reflection of health, especially when it comes to assessing risk for chronic diseases.

Let’s break down the differences between BMI and body fat, how each is measured, and why body fat may offer a clearer picture of your health.

What Is BMI?

BMI (Body Mass Index) is a simple mathematical formula that estimates body fat based on height and weight:

BMI = (weight in pounds / height in inches²) x 703

For example, someone who is 5’6” (66 inches) and weighs 160 pounds would have a BMI of about 25.8.

BMI falls into standardized categories:

• Below 18.5 – Underweight
• 18.5–24.9 – Healthy weight
• 25–29.9 – Overweight
• 30 and above – Obesity

Because it’s quick and easy to calculate, BMI is widely used in healthcare settings as a general screening tool. If someone’s BMI is elevated, providers may do further assessments, like measuring waist circumference or evaluating lifestyle and family history.

However, BMI has significant limitations. It does not account for:

• Muscle mass
  
• Gender differences
  
• Age
  
• Fat distribution (like abdominal fat)
  
• Ethnic or racial variation in body composition
  

For instance, an athlete with a lot of muscle might have a “high” BMI but low body fat. Conversely, someone with a “healthy” BMI might still carry dangerous levels of visceral fat (the kind that surrounds organs and increases disease risk).

Bottom line: BMI is helpful as a starting point, but it can be misleading when used in isolation.

What Is Body Fat Percentage?

Body fat percentage measures how much of your body weight is composed of fat. Unlike BMI, it distinguishes between fat and lean tissue (muscle, bone, organs, etc.), making it a more nuanced and accurate assessment of body composition.

There are two main types of fat:

• Subcutaneous fat: found just under the skin
  
• Visceral fat: stored deep in the abdomen, around organs—this type is more strongly associated with chronic diseases

Why Body Fat Percentage Matters

Research shows that visceral fat is a better predictor of metabolic and cardiovascular risk than BMI. In other words, even if you have a “normal” BMI, having too much fat—especially around your midsection—can increase your risk for conditions like:

• Type 2 diabetes
  
• Heart disease
  
• High blood pressure
  
• High cholesterol

A 2023 study involving over 3,000 adults found that nearly 1 in 3 people with a “healthy” BMI had excess body fat—and many of them had elevated cholesterol and triglyceride levels or larger-than-ideal waist circumferences. BMI alone would not have flagged these individuals as being at higher risk.How to Measure Body Fat Percentage

There are a few ways to measure body fat, some more accurate (and expensive) than others:

1. Skinfold measurements (using calipers to pinch fat at various body sites)
   
2. Waist circumference and waist-to-hip ratio
   
3. Bioelectrical Impedance Analysis (BIA) (uses electrical signals to estimate fat vs. lean mass)
   
4. DEXA scan (a specialized X-ray that shows fat, muscle, and bone distribution)
   
5. Air displacement plethysmography (Bod Pod)
   

Each method has pros and cons in terms of cost, accuracy, and accessibility. While some (like DEXA scans) offer precision, they may not be widely available outside of clinical or research settings.

What’s Considered a “Healthy” Body Fat Percentage?

Unlike BMI, there is no universally accepted standard for healthy body fat percentage, as it varies based on age, sex, and individual body type.

General guidelines:

• Women: 35% or more
• Men: 25% or more

These thresholds are often used to identify individuals at greater risk for weight-related conditions, but your ideal range may differ depending on your lifestyle, health history, and goals.

BMI vs. Body Fat: Key Differences

Measures

• BMI: Weight relative to height
• Body Fat %: Fat relative to total body mass

Ease of Measurement

• BMI: Very easy
• Body Fat %: Requires tools or clinical tests

Accounts for Fat vs. Muscle

• BMI: No
• Body Fat %: Yes

Cost

• BMI: Free
• Body Fat %: Can be costly

Accuracy for Individuals

• BMI: Lower
• Body Fat %: Higher

Health Insights

• BMI: General screening tool
• Body Fat %: More specific health risk indicator

So, Which One Should You Focus On?

Body fat percentage tends to be the better indicator of health risk, especially when evaluating long-term metabolic and cardiovascular health. However, BMI is still useful as a quick initial screen.

Here’s the key takeaway: Neither BMI nor body fat percentage alone tells the whole story. Ideally, they should be looked at together—and in context of other factors like lifestyle, waist circumference, blood work, and overall fitness.

How to Move Toward a Healthier Weight and Body Composition

Regardless of your current BMI or body fat percentage, the following habits can support a healthier body:

• Eat more whole foods and high-protein meals
  
• Get moving daily—even walking can lower visceral fat and improve metabolic health
  
• Stay hydrated—aim for at least 8 glasses of water a day
  
• Prioritize sleep—poor sleep can increase fat retention and slow metabolism
  
• Track progress over time using waist measurements or progress photos—not just the scale

While BMI and body fat percentage both offer insight into your health, body fat percentage often gives a more accurate, individualized picture—especially when it comes to identifying risks not obvious from weight alone.

If you’re unsure where you stand, speak with a healthcare provider who can assess your full health profile and recommend the most appropriate next steps.