Everything You Want to Know About Body Fat

Determining your percent body fat is very important because the amount of fat in your body is related to health as well as fitness and sports performance. In fact, if you go to a gym or health club, assessing your percent body fat has become quite common. But what exactly is body fat? What percent body fat is healthy for men and women? Here we try to answer the most common questions about body fat.

What is Body Fat?

Fat is one of the basic components that make up the structure of your body. The other components include muscle, water, bone and your organs — the brain, liver, kidneys, spleen, stomach, pancreas, and intestines. etc. All are necessary for normal, healthy functioning.

Body fat can be divided into two categories: Essential fat and storage fat. As its name implies, essential fat is necessary for normal, healthy functioning. It is stored in small amounts in your bone marrow, organs, central nervous system and muscles. In men, essential fat is approximately 3% of body weight. Women, however, have a higher percentage of essential fat — about 12%. This is because their essential fat also includes some sex-specific fat found in the breasts, pelvis, hips and thighs. This sex-specific fat is believed to be critical for normal reproductive function.

Storage fat is the other type of body fat. This is the fat you accumulate beneath your skin, in certain specific areas inside your body, and in your muscles. It also includes the deep fat that protects your internal organs from injury. Men and women have similar amounts of storage fat.

It is desirable to have some storage fat due to the protective role it plays in your body. However, most storage fat is considered to be "expendable". Storage fat:

  • increases when you gain weight
  • is what you want to lose when you lose weight. Many Americans have too much storage fat, while some have too little. Too much or too little storage fat is unhealthy.

What is the Healthy Range of Body Fat?

For the average adult the healthy range of body fat is shown below. The ranges are different for men and women depending on their age.

Healthy Range of Body Fat
Age Female Male
18-39 21-32% 8-19%
40-59 23-33% 11-21%
60-79 24-35% 13-24%

Professional and superior amateur athletes often have a body fat percentage much lower than the average person. For example, male marathon runners have been found to have body fat as low as 3.3% and female Olympic swimmers have been found to have body fat as low as 14.5%.

What happens when your percent body fat goes above the desirable range? Your risk for developing heart disease, high blood pressure, gallstones, type 2 diabetes, osteoarthritis, certain cancers and for an early death increases. In some cases, the excess fat becomes a mechanical barrier to breathing properly. This condition is called sleep apnea.

Where your excess fat is located is even more important than the amount of body fat you have. Recent studies have shown that if you carry your extra fat around your waist, you are at a higher risk for developing the diseases mentioned above than if you carry the same amount of extra fat around your thighs and buttocks.

Can Body Fat Be Too Low?

The answer is YES for both men and women.

If a man's body fat is less than 3%, his health may be compromised because normal, healthy functioning requires some fat. He may become more susceptible to illness or experience chronic fatigue. Remember that 3% the amount of body fat considered to be essential for men.

Based on current information, a woman must have a minimum percent body fat of 13-17% for regular menstruation. If a woman's percent body fat is too low, her periods may stop and she may experience infertility. Her menstrual irregularities may also compromise the health of her bones, normal hormonal function is necessary for bone health.

Women, and an increasing number often men, with eating disorders — anorexia and sometimes bulimia — can lose large amounts of fat. Thus having too little fat can be a sign of the presence of an eating disorder.

For information on gaining weight, check out the Cyberkitchen.

What Is Lean Body Mass?

Lean body mass is commonly used to describe the muscles in your arms, legs, back, neck and abdomen. But actually it also includes your heart muscle, and the tissues of your other internal organs as well as water, and bone. This is the part of your body you want to preserve or expand.

How much lean body mass you have is the most important factor in determining your metabolism (the rate at which you burn the calories). The higher the amount of your lean body mass, the higher your metabolic rate and the more calories you will burn when you are sitting or lying down. This higher metabolic rate makes it easier to maintain your weight.

Want to build up your lean body mass? The good news is that you can increase the amount and the strength of your muscles through a regular program of strength training — also known as "resistance" training.

What Happens When You Gain Weight?

Fully grown adults gain both lean body mass and storage fat when they gain weight. The amount of fat gained usually far exceeds the amount of lean body mass gained. The exception to this is if you are involved in a training program specifically aimed at increasing your muscle mass.

More specifically, the extra weight you gain is about 60-80% fat and 20-40% lean body mass. Therefore, if you gained 10 pounds, about 6-8 pounds would be fat and 2-4 pounds would be lean body mass. This would mean increases not only in your fat tissue but also in your muscles, stomach, intestines and other organs, bone and water.

What Happens When You Lose Weight?

When you lose weight, you lose water, lean body mass and storage fat. To replace lost water, it is important to maintain proper hydration. From a health standpoint and to maintain your metabolic rate, it is better to preserve as much lean body mass as possible as you reduce your body fat.

How much fat and lean body mass should you lose when you lose weight? Experts have determined that:

  • during the early weeks of weight loss, at least 75% of the weight you lose should be fat loss and not more than 25% should come from lean body mass.
  • as you continue to lose weight, especially if certain types of exercise are included in your weight loss plan, fat loss should be about 90% of the weight you lose and lean body mass should be about 10%.

What is the Best Method to Lose Weight?

The best method for losing weight is to follow a program that helps you to maintain hydration, lose more storage fat, and lose as little lean body mass as possible. Such programs promote a balanced eating pattern and a well rounded program of physical activity that includes some strength training to build or preserve muscle.

  • Balanced eating means including foods from all food groups and portion control.
  • Physical activity not only boosts metabolic rate and burns calories, but strength training also plays an important role in building and preserving muscle as you burn fat. Finally, weight bearing activities such as walking help to maintain and improve bone density.

The average rate of weight loss should be no more than two pounds a week. If the calories you eat are too low and you lose weight too fast, you will lose a greater percentage of lean body mass than is desirable. Some dietary strategies may allow you to lose pounds faster; however they promote the loss of both lean body mass and body water. Therefore, even though the pounds you lose may be higher, you will be losing the wrong type of weight.

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