What Is Body Composition?

Medically Reviewed by Zilpah Sheikh, MD on June 24, 2024
5 min read

Body composition is a term often used often by doctors and health and fitness professionals. It refers to the percentage of fat, bone, and muscle in your body. It can give your doctor a better idea of your physical health and fitness than your body weight alone. Your doctor may use it to learn more about your nutrition, health status, and risks of disease. In the fitness world, it's used to keep track of how effective a particular program is for fat loss and muscle gain. 

Weighing yourself only tells you one thing: your total weight. Body composition, on the other hand, gives you a much more detailed picture of your weight health because muscle is denser than fat. Someone with lots of muscle can weigh more than someone with a lot of extra fat, even though they look leaner. 

Making this distinction helps you have a clearer picture of your fitness level and health risks. Having excess body fat is linked with many diseases. It can put you at risk of cancer, heart disease, diabetes, and more. 

Body fat percentage is how much of your body is made up of fat vs. bone and muscle. For example, a body fat percentage of 25% means that one-quarter of your body is composed of fat, and 75% is bone and muscle. 

Body fat percentage chart

There are established guidelines for optimal body fat percentage for your age and sex:


If your numbers are higher than these, you are considered overweight, or obese if they are very high. If your percentage is lower than these, you are considered underweight. Note that these are just estimates and will not tell the whole story for every person. It's important to discuss your results with your doctor, who can give you experienced feedback based on your health status and health history.

It's easy to get body fat percentage and body mass index (BMI) mixed up. BMI is another measurement doctors use to assess your weight health. It uses your height and weight to estimate your body fat level. BMI is calculated by dividing your weight in kilograms by your height in meters squared. You can do the calculation yourself, or use an online calculator like this one.

Just like body fat percentage, there are established guidelines for optimal BMI:

BMIWeight Status
Below 18.5Underweight
18.5-24.9Healthy weight
30.0 and aboveObesity


BMI is not nearly as effective as measuring body fat percentage. But it's much easier to pop some numbers into an equation than it is to do a body fat test. There are many factors involved with BMI that can affect your numbers. It doesn't take into account your muscle mass. So, you might be very muscular and have a high BMI, even though you're lean and healthy. It's also affected by age, gender, and race/ethnicity.

There are several ways to find out your body composition, ranging from simple and less accurate to complex and more accurate.

Skin calipers. A health professional will use skin calipers to measure your skinfold thickness. They’ll measure areas where stored fat is commonly found. With good technique, skin calipers can be fairly accurate. But human error can cause many fluctuations.

Bioelectrical impedance. This analysis sends electrical currents through your body. It then measures the speed at which they travel. It’s the easiest method of measuring your body fat after skin calipers. But the accuracy is only fair. It’s best for monitoring changes in your body fat over time.

Air displacement (body pod). This kind of machine measures how much air your body displaces. This helps calculate your body density, after which you can figure out your body fat level.

Dual X-ray absorptiometry (DEXA) scan. A DEXA scan uses low-level X-rays to find how much fat, muscle, and bone are in your body. It's quick and also includes bone in the assessment.

Underwater weighing. When underwater, your lean tissue sinks, and fat floats. People with higher amounts of body fat weight less underwater. Your underwater weight helps estimate how much fat mass you have.




You can improve your body composition and your health at the same time. To do this, you need the right combination of burning calories and building muscle:

Diet. Focus on a balanced diet that includes plenty of fruit, vegetables, whole grains, and lean protein. Don't skip meals, but control your portion sizes. Make sure to eat enough protein to support muscle growth and repair. Limit processed foods, sugary drinks, and unhealthy fats, like saturated fat. 

Exercise. Do regular cardio and strength training. Cardio helps you burn calories, and strength training build muscle mass. Aim for at least 150 minutes of moderate-intensity cardio or 75 minutes of vigorous-intensity cardio each week. Do strength training exercises that target all your major muscle groups at least 2 days a week. 

Lifestyle. Getting enough sleep is crucial for maintaining your weight. Aim for 7 to 9 hours a night. Manage your stress levels, as stress can also lead to weight gain. 

Body composition is the amount of fat, bone, and muscle in your body. Having a good body composition is an important part of staying healthy, as having too much fat can increase your risk of illness. If you're interested in finding out your body composition, ask your doctor or a fitness professional where you can have a body fat test done. 

How can you calculate body fat percentage at home?

You can use a home scale with bioelectrical impedance that can give you a rough estimate of your body fat percentage. If you know how, you can also use skin calipers. The accuracy of both these methods isn't very high.

What is best for good body composition?

A healthy diet and regular exercise, including cardio and strength training, is the best way to burn fat and build muscle. 

What is a healthy body fat percentage for women?

A range between 16% and 33% is considered healthy for women, depending on age. As you age, body fat increases. 

Does adipose tissue contribute to total body composition?

Yes. Adipose tissue is fat mass.