Do you have a love-hate relationship with your bathroom scale? The scale may measure your weight but not accurately reflect your true health. Body composition takes your weight measurement one step further, figuring out what percentage of your weight is fat, muscle, and bone.
The difference between fat mass and non-fat mass (muscle and bone) paints a more complete picture of your health and fitness. Learn the basics of your body composition, what it means, and what you can do about it.
We've tried, tested, and reviewed the best bathroom scales. If you're in the market for scale, explore which option may be best for you.
What Is Body Composition?
Body composition is the phrase used by medical professionals and the health community to refer to the percentage of fat, water, bone, muscle, skin, and other lean tissues that make up the body. Knowing your body composition provides more detailed information about your health. Two people can weigh the same but have different wellness and fitness needs due to their body composition.
Why Is Body Composition Important?
Body composition measures your overall health and fitness level in terms of your body fat percentage. It measures the difference between how much of your weight comes from fat and how much from muscle, unlike your bathroom scale which measures weight only.
Less fat and more muscle tend to point toward a better level of health.
What Is Body Fat?
Body fat includes all fat stored in your body. There are two types of body fat:
- Subcutaneous fat: This is the layer of fat under your skin. It insulates and protects your body.
- Visceral fat: This fat surrounds and cushions your abdominal organs.
In addition to insulating and protecting your body, fat provides energy, carries fat-soluble vitamins, makes certain hormones, and serves as a building-block for cell membranes.
You need a certain amount of body fat to perform these functions—this is known as essential fat.
Body Fat Percentage
Body fat percentage is the percent of fat that makes up your total body weight. Many factors influence your body fat percentage, including gender, age, fitness level, and lifestyle.
The body fat percentage ranges come from the American Council on Exercise (ACE).
ACE Body Fat Percent Norms for Men and Women | ||
---|---|---|
Description | Women | Men |
Essential Fat | 10% to 13% | 2% to 5% |
Athletes | 14% to 20% | 6% to 13% |
Fitness | 21% to 24% | 14% to 17% |
Acceptable | 25% to 31% | 18% to 24% |
Obese | Over 32% | Over 25% |
Athletes tend to have a lower body fat percentage than people who are physically fit because having less fat improves their athletic performance. However, when body fat percentages dip too low, athletic performance suffers and immune function declines.
On the flip side, a body fat percentage that’s too high is a risk factor for chronic illnesses like diabetes, high blood pressure, and heart disease.
Body Composition vs. Body Mass Index
Body composition and body mass index (BMI) are tools that assess body fatness. However, the methods used to measure body composition and BMI differ. Additionally, BMI may not provide accurate results in all situations.
Body Mass Index is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age. Despite being a flawed measure, BMI is widely used in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.
Body Mass Index
BMI is a tool that has been used by health professionals to assess body fatness and health. It’s a mathematical equation that compares your weight to your height.
- BMI = (weight in pounds)/(height squared) X 703
For example: (150 pounds)/(66 inches x 66 inches) X 703 = 24
This BMI table is from the Centers for Disease Control and Prevention (CDC).
- Less than 18.5 = underweight
- 18.5 to 24.9 = healthy weight
- 25.0 to 29.9 = overweight
- 30 or higher = obesity
You don’t need any special equipment to measure BMI, making it a quick tool to assess body fat and health.
How to Measure Body Composition
There are several ways to measure body composition. However, you need more than a bathroom scale and calculator to figure out what percentage of your weight comes from fat and what comes from muscle. A smart scale can help you monitor various key metrics.
Bioelectrical Impedance
Bioelectrical impedance (BIA) is a tool that estimates your body composition by measuring your body’s resistance to a low-level electric current, or impedance. Muscles have a lower resistance to an electric current than fat.
Painless, quick, and easy
You can purchase scales with BIA technology to use at home
Not a good predictor of body fat percentage in all people
Hydration affects results
Skinfold Measurements
Skinfold measurements involve the use of special calipers that measure the skinfold—subcutaneous fat—on different parts of your body. Skinfold calipers are perhaps the most portable type of body fat monitors on the market. Fitness trainers use skinfold measurements to assess body fat because it’s quick and convenient.
You can wear shorts and a T-shirt when getting measured
The test is quick and painless
Difficult to get accurate results when performed by someone without proper training
Not a good tool for measuring body composition in people with weight challenges
DEXA Scan
The DEXA scan, or dual-energy X-ray absorptiometry scan, uses a low-level X-ray to measure bone, muscle, and body fat.
Fast and painless test
Provides regional body composition
Measures bone mineral density
Requires trained medical professionals for testing
Not suitable for all body types
Hydrostatic Weighing
Hydrostatic weighing involves full submersion in a water tank, using water displacement to measure body composition. Since fat floats and muscle sinks, a person with more lean body mass weighs more underwater.
Gives the most accurate results
Not widely available
Requires special equipment and professional testers
Bod Pod
Bod pod is similar to hydrostatic weighing but uses air displacement instead of water displacement to measure body composition. For this test, you sit in an egg-shaped chamber which uses your body weight and volume to determine your body composition.
Test is quick and provides a print out of your measurements, including calorie needs
Results are accurate
Overestimates body fatness in lean individuals
Clothing and facial hair may affect results
Factors to Consider
Body composition provides valuable information about body fat percentage. However, your body shape is unique to you and there are uncontrollable factors that affect your body composition, including:
- Age: You lose muscle as you age, affecting your body composition. However, age-related muscle loss is most often due to decreased physical activity.
- Genes: Your genes determine your body type and composition and your inherited body type may have more fat that’s hard to lose.
- Hormones: Hormones also influence body composition. Testosterone is a male sex hormone that increases muscle mass.
- Gender: Due to genetics and hormones, women have more body fat than men.
Changing Your Body Composition
To change your body composition, you need the right balance of physical activity and nutrition to reach your goals. Slow and steady changes work best when you want to increase muscle and lose fat. It's important to remember that some factors will remain out of your control.
Before making any changes to your diet or workout routine, consult with your primary care provider or a registered dietitian for guidance.
A Word From Verywell
Your body composition may help you better understand your current level of health and fitness. It can also serve as a measuring tool to monitor progress when starting a new fitness or wellness program.
When trying to change your physique to improve your fitness level, it’s important to implement a safe and effective workout routine and a balanced eating plan. Seek advice from a healthcare professional before making any major changes to your diet or exercise routine.
Frequently Asked Questions
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The three somatotypes include ectomorphs, endomorphs, and mesomorphs. These body types are determined by your genetics.
A person with an ectomorph body type has very little body fat and muscle and struggles to gain weight. Someone with an endomorph body type, on the other hand, has a high percentage of body fat and muscle and has no problems gaining weight. Mesomorphs have an athletic build and can gain and lose weight easily. -
The 4-component model of body composition measures body fat, water, mineral, and protein content to assess body composition. By comparison, the traditional 2-component model only uses fat mass and fat-free mass to assess body composition.
Because the 4-component model measures multiple components to assess fat mass and fat-free mass, it provides more accurate measurements for those who don’t fit the traditional body composition references.
This model is often used to measure body composition in children. -
According to data from the American Council on Exercise, body fat percentages for males generally range from 18% to 24% and for females 25% to 31%. Body fat percentages that measure higher than that range classify someone with obesity.
If you’re an athlete or regular gym-goer, it’s possible to have a body fat percentage lower than the acceptable range for your sex and still be healthy. However, a body fat percentage less than 5% for males and 10% for females is unhealthy.