Learning About Body Fat Testing

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Body fat testing

What is body fat testing?

Body fat testing checks how much body fat you have. It may be done to find out if you have too much or too little body fat.

The test is one of the ways to measure healthy weight.

People who are trying to become more fit and lose weight sometimes use the test to check for changes in their body fat levels.

How is body fat measured?

There are several ways to estimate body fat. The easiest and most popular ways to test are not as accurate as more expensive methods.

The least expensive and most popular tests include:

  • Skinfold thickness. A tool called a caliper is used to measure the thickness of fat at one or more places on your body. It is most accurate when a well-trained person measures fat thickness from several sites.
  • Bioelectrical impedance. A small electrical current is passed through your body to measure your body's electrical resistance. This resistance is used along with your height and weight to calculate your body fat. Results can vary based on how much water is in your body and where the electrodes are placed. You can buy some devices, including body fat scales, that calculate your percentage of body fat using this method.

More accurate tests are available, but they can be harder to find and can cost a lot. They include:

  • Underwater weighing. This is also called hydrodensitometry. It is based on the principle that fat tissue is less dense than muscle and bone.
  • DXA. This is also called dual-energy X-ray absorptiometry. DXA is a type of X-ray that can tell how much fat tissue you have and where it is.
  • Air displacement plethysmography. This is similar to underwater weighing, but it uses air instead of water.

What do the results mean?

The results of a body fat test give an estimate of how much of your body weight comes from fat.

But body fat percentage is not the best way to measure your risk for weight-related diseases. Your doctor may suggest checking your BMI (body mass index) and your waist size instead. A higher BMI or waist size may mean that your weight is raising your risk for health problems.

How do you get to and keep a healthy amount of body fat?

  • Get at least 30 minutes of exercise on most days of the week. Walking is a good choice. You also may want to do other activities, such as running, swimming, cycling, or playing tennis or team sports. Moderate exercise is safe for most people, but it is always a good idea to talk to your doctor before starting an exercise program.
  • Build muscle by strength training 2 to 3 times a week. You can use weights, elastic bands, or your own body weight. Talk with your doctor about strength training that is right for you.
  • Eat healthy foods. These include fruits, vegetables, lean meats and dairy, and whole grains. Do not eat too much sugar, fat, or fast foods. You can still have dessert and treats now and then. The goal is moderation.
  • Start small to improve your eating habits. Pay attention to portion sizes, drink less juice and soda pop, and eat more fruits and vegetables.
    • Eat a healthy amount of food. A 3-ounce serving of meat, for example, is about the size of a deck of cards. Fill the rest of your plate with vegetables and whole grains.
    • Limit the amount of soda and juice you have every day. Drink more water when you are thirsty.
    • Eat plenty of fruits and vegetables every day. Try to eat 2 to 3 cups of vegetables a day and 1 1/2 to 2 cups of fruit a day. It may seem like a lot, but it is not hard to reach this goal. Have an apple or some carrot sticks as an afternoon snack. Try to have fruits and/or vegetables at every meal.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.