The body is composed of water, protein, minerals, and fat. A two-component model of body composition divides the body into a fat component and fat-free component. Body fat is the most variable constituent of the body. The total amount of body fat consists of essential fat and storage fat.
Essential Fat is necessary for normal body functioning and is found in the following places:
- Bone Marrow
- Heart
- Lungs
- Liver
- Spleen
- Kidneys
- Intestines
- Muscles
- Lipid-rich tissues throughout the central nervous system
Storage Fat, on the other hand, accumulates in adipose tissue and is located around internal organs (internal storage fat) and directly beneath the skin (subcutaneous storage fat). It provides bodily protection and serves as an insulator to conserve body heat.
The relationship between subcutaneous fat and internal fat may not be the same for all individuals and may fluctuate during the life cycle.
Importance
Health practitioners universally agree that too much body fat is a serious health risk. Problems such as hypertension, elevated blood lipids (fats and cholesterol), diabetes mellitus, cardiovascular disease, respiratory dysfunction, gall bladder disease, and some joint diseases are all related to obesity. Also, some research suggests that excessive accumulation of fat at specific body sites may be an important health risk factor. 1 For instance, it appears that extra fat around the abdomen and waist is associated with higher risk of diabetes, heart disease, and hyperlipidemia. Individuals who accumulate a lot of fat around the waist (apple-shaped) are worse off than those who tend to accumulate fat in the thighs and buttocks (pear-shaped). The apple-shaped pattern of fat deposition is more commonly seen in men; whereas women tend to be pear-shaped.
Now, more than ever before, people are preoccupied with how much they weigh. In an effort to lose weight and excess fat, Americans spent in 1989 an excess of 30 billion dollars for 54 million diet books and for services and products at 1500 weight control clinics. 2 Yet, efforts such as these to achieve thinness are often based on popular misconceptions about body weight and body composition. Being thin does not necessarily reduce one’s health risk. In fact, obsession with becoming thin often leads to serious eating disorders such as anorexia and bulimia. Thinness simply refers to weighing less than the recommended values in age-height-weight tables. Leanness, on the other hand, refers to the muscle, bone, and fat composition of your body weight. Although some lean individuals may actually weigh more than their “tabled” ideal body weight, low body fat lessens the risk of health problems.
Understanding the difference between healthy leanness and undesirable thinness is important. In addition, there are some other reasons to become more informed about body composition:
- To develop complete physical fitness profiles
- To monitor body fat loss and muscle growth resulting from exercise.
- To provide baseline data for nutritional counseling and treatment of obesity.
- To describe changes due to growth, development, maturation, and aging.
- To maximize the performance of athletes.
Lean Body Mass
Lean body mass represents the weight of your muscles, bones, ligaments, tendons, and internal organs. Lean body mass differs from fat-free mass. Since there is some essential fat in the marrow of your bones and internal organs, the lean body mass includes a small percentage of essential fat. However, with the two-component model of body composition, these sources of essential fat are estimated and subtracted from total body weight to obtain the fat-free mass. MuscleSound is the most practical method of assessing body composition. It is based on the two-component (fat and fat-free mass) model of body composition.
This information is particularly valuable if a client is going on a weight loss diet. Oftentimes diets will result in loss of mostly lean body tissue and water. By tracking a client’s body fat you can closely monitor what body composition changes are actually happening. Just knowing how many pounds a person has lost is insufficient. The goal of any weight control program is going to involve adjusting a person’s exercise and dietary habits to reach that ideal percentage of body fat.
Body composition is an integral component of total health and physical fitness. We promote leanness, not thinness, to enhance lifetime physical and mental well-being.
- Wilmore, J. H., Buskirk, E. R., DiGirolamo, M., & Lohman, T. G. (1986). Body composition: A round table. The Physician and Sportsmedicine, 14(3), 144-162.
- McArdle, W. D., Katch, F. I., & Katch, V. L. (1991). Exercise physiology: Energy, nutrition, and human performance (3rd ed). Philadelphia: Lea & Febiger.
Do you have a love-hate relationship with your bathroom scale? The bathroom scale may be a good tool for measuring weight, but it may not accurately reflect your true health. Body composition takes your weight measurement one step further, figuring out what percentage of your weight comes from 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.
This article reviews the basics of your body composition, what it means, and what you can do about it.
Your body composition determines what percentage of your total body weight comes from fat, muscle, and bone. Knowing your body composition provides more detailed information about your health. Two people can weigh the same, but have very different wellness and fitness needs because of their body composition.
Body composition is important because it measures your overall health and fitness level in terms of your body fat percentage. Your bathroom scale can’t tell the difference between how much of your weight comes from fat and how much from muscle. But body composition measurements can.
Less fat and more muscle tends to point toward a better level of health.
Body fat includes all the stored fat 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 is the fat that 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 is the percent of fat that makes up your total body weight. Many factors influence your body fat percentage, including sex, age, fitness level, and lifestyle.
The body fat percentage ranges come from the American Council on Exercise (ACE).
| 10% to 13% | 2% to 5% |
| 14% to 20% | 6% to 13% |
| 21% to 24% | 14% to 17% |
| 25% to 31% | 18% to 24% |
| 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 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.
Health professionals use the BMI to assess an individual's risk for disease based on their body fatness, or where they fall on the BMI table. But recent evidence suggests that the BMI is a very poor measure of body fatness and disease risk, and may not serve as the best—or only—metric for measuring body composition and health.
Body Mass Index (BMI) 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 today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.
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.
However, the BMI isn’t perfect and may not accurately assess body fatness in all people. For example, a bodybuilder may have a BMI that puts them in the overweight category, but have a low body fat percentage.
There are a number of 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 percentage comes from muscle.
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.
Pros
Painless, quick, and easy
You can purchase scales with BIA technology to use at home
Cons
Not a good predictor of body fat percentage in all people
Hydration affects results
Skinfold measurements involve the use of special calipers that measure the skinfold—subcutaneous fat—on different parts of your body. Fitness trainers use skinfold measurements to assess body fat because it’s quick and convenient.
Pros
You can wear shorts and a t-shirt when getting measured
The test is quick and painless
Cons
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
The DEXA scan, or dual-energy X-ray absorptiometry scan, uses a low-level X-ray to measure bone, muscle, and body fat.
Pros
Fast and painless test
Provides regional body composition
Measures bone mineral density
Cons
Requires trained medical professionals for testing
Not suitable for all body types
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.
Pros
Gives the most accurate results
Cons
Not widely available
Requires special equipment and professional testers
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.
Pros
Test is quick and provides a print out of your measurements, including calorie needs
Results are accurate
Cons
Overestimates body fatness in lean individuals
Clothing and facial hair may affect results
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 get older, which affects your body composition. However, age-related muscle loss is most often due to a decrease in physical activity.
- Genes: Your genes determine your body type and composition and your inherited body type may have more body fat that’s hard to lose.
- Hormones: Hormones also influence body composition. Testosterone is a male sex hormone that increases muscle mass.
- Sex: Due to a combination of genetics and hormones, women have more body fat than men.
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.
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 health care professional before making any major changes to your diet or exercise routine.
Frequently Asked Questions
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Which are the 3 somatotypes (body types)?
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.
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What is the 4-component model of body composition?
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.
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What is a healthy body fat percentage for males and females?
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.