4 Ways to Measure Your Body Composition

Why You Need to Know Your Body Composition

Measuring body composition will help you make diet and exercise choices.
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Body composition refers to the amounts of you that are fat, water, bone and lean mass. Measuring and monitoring your body composition will help you know if your current diet and exercise program is working, or if you need to make some changes.

There are four common ways you can measure your boy composition at home. You can weigh yourself, calculate your body mass index, determine your body fat percentage, or get out your measuring tape and take a few measurements. 

Seems easy, right? Well, it is -- but flip through the slideshow to learn more about how to do these body composition measurements at home.

Weigh Yourself on a Scale

Woman weighing herself at home
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A typical bathroom scale is easy to use because all you need to do is stand on it, then the scale shows you a number that corresponds to your weight. You'll want to see the number on the scale go down if you wish to lose fat, but you might prefer to see that number go up if you want to gain muscle.

You can use the scale to track changes in your weight over time, but remember that fat loss and muscle gain aren't the only things that can affect the numbers. Your body weight naturally fluctuates during the day depending on what you eat. For example, foods high in sodium may cause some people to retain fluid, which will show up temporarily on the scale as weight gain. Regular monthly hormonal changes can cause many women to see their weight change due to bloating and fluid retention.

It can be very disappointing to step on the scale expecting to see weight loss and see a little weight gain instead, so don't get upset.

Instead, keep these tips in mind whenever you step on your bathroom scale:

Weigh yourself on the same scale each time. Scales aren't always accurate or precise. Your scale may read a couple of pounds different from your best friend's scale or the scale at the health club. By using the same scale each time; your actual changes in weight will be accurate.

Always weigh yourself at the same time of day. You might find your weight changes by a pound or two throughout the day so choose a time of day that's most convenient for you and always weigh yourself at that time.

Wear the same amount, or no clothing. If you're using a bathroom scale at home, you can shut the door and step on the scale in the nude. If you use a scale at your health club, you may need to keep your clothes on (unless it's in the locker room), so always wear a similar weight of clothing - like your workout t-shirt and shorts.

Don't become a slave to the scale. It's tempting to hop on the scale each time you're near  -- just to check on your progress -- but weight loss or gain is a slow process. Constantly checking your weight isn't going to help you lose weight any faster. It might even leave you feeling disappointed when you're hoping for quick changes.

Some people like to weigh themselves every day, but using the bathroom scale once each week is probably often enough to track your progress. Once you reach your goal weight, you'll still need to weigh yourself periodically in case the numbers start to go up (or down) again. That way you can get your diet back on target before gaining or losing too much weight.

Don't rely on the scale as your only body measurement. There are other methods for monitoring your weight, such as estimating body fat percentage (many scales have this built-in), calculating your Body Mass Index, or using a measuring tape to measure your waist to hip ratio, or determine your clothing size.

Know Your Body Fat Percentage

Body fat percentage monitor measures body fat.
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Body fat percentage is the amount of you that's fat. We all need some fat, but when your body fat percentage gets too high, you're putting yourself at a higher risk for cardiovascular disease, arthritis, some forms of cancer, and diabetes.

By monitoring body fat percentage, you'll have a better idea if you're losing fat or muscle. Or if you're gaining weight.

Measuring Your Body Fat Percentage

A body fat monitor is a device you can use at home to measure your body fat percentage. It sends a small current of electricity through your body, then analyses how different tissues -- fat, lean tissue, and fluid -- react to the current. These hand-held devices require you input your height, age, and weight. Then all you need to do is hold the device for a few seconds.

Or you can make it even easier by stepping on a body fat scale that calculates body composition along with your total body weight. Body fat scales are easy to find and easy to use, just input your age, height, and sex, then step on the scale and in a few seconds you'll have your readings. 

Need Something More Accurate?

Body fat monitors and scales are easy to use and fairly accurate, but if you want something even more accurate, you need to see a health professional who uses a different method.

For example, he or she may use a set of calipers to pinch the fat folds on various parts of your body. These measurements, along with your height weight are used to determine your body fat percentage. You can buy body fat calipers to use at home, but you'll need help from another person.

Some health care providers offer DEXA, which stands for dual energy X-ray absorptiometry. DEXA machines can measure bone density as well as body fat percentage. 

Hydrostatic weighing involves being dunked under water in a big tank and exhaling completely. Bod Pods are similar, but they measure the displacement of air rather than water. These two methods are very accurate, but obliviously not something you can do at home.

What's a Good Body Fat Percentage?

Two people who weigh the same can have completely different body shapes. A muscular person with a big body frame may weigh the same as someone with a smaller frame and a lot more fat.

If you want to lose weight, you probably want to keep the amount of muscle you have and reduce your body fat. If you want to gain weight, you'll want to gain both muscle and fat.

According to the American Council on Exercise, the following chart shows whether or not your body fat percentage is in a healthy range:

Essential Fat: 2-5 percent
Athletes 6-13 percent
Fitness 14-17 percent
Acceptable 18-24 percent
Obesity greater than 25 percent

Essential Fat: 10-13 percent
Athletes 14-20 percent
Fitness 21-24 percent
Acceptable 25-31 percent
Obesity greater than 32 percent

Your body fat percentage is not the same as your Body Mass Index, which is a different measurement, and the charts are not the same, so don't confuse the two.

Calculate Your Body Mass Index

Calculate your body mass index.
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The Body Mass Index (BMI) combines your weight and your height into a score that helps you determine if you are underweight, at a healthy weight, overweight, or obese.

Since a typical scale only measures your total weight, it helps to have more information to determine if that weight is healthy or unhealthy. A person who is six feet tall and weighs 198 pounds is probably going to have a smaller amount of body fat than a person who is five feet tall and 198 pounds. 

BMI is calculated by the following formula:

weight (lb) / [height (in)]2 x 703

or in metric:

weight (kg) / [height (m)]2

You can use a BMI calculator to do the math for you.

You can compare your BMI to this table to help you determine whether you're at a healthy weight.

  • Underweight = less than 18.5
  • Normal weight = 18.5-24.9
  • Overweight = 25-29.9
  • Obese = 30 or greater

If you are planning to lose or gain weight, you can use your BMI to monitor your progress. It's important to know that your BMI is not the same as your body fat percentage, which is a different number and doesn't correspond to these charts.

People who have a BMI in the overweight or obese ranges may be at a higher risk for cardiovascular disease, diabetes, arthritis, and some forms of cancer. It's important to see your health care provider, to evaluate your health.

Body Mass Index Doesn't Work for Everyone

The BMI isn't perfect because it's an indirect measurement of fat, so really doesn't differentiate pounds of fat from pounds of muscle and bone. It doesn't work well for very muscular people or for people who have lost a lot of muscle mass.

For example, an elite athlete with a slight amount of body fat will still have a high BMI, and an elderly person may have a lower BMI because they have less muscle mass. In these cases, a better method of measurement is the body fat percentage.

Use a Measuring Tape

Use a tape measure to measure your body.
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Taking body measurements doesn't require anything fancy - just a cloth measuring tape you can buy at any craft shop or any store that sells craft and sewing supplies. You can choose inches or centimeters, whichever you prefer.

Two good parts of your body to measure are your waist and your hips -- that's because both your waist measurement and your waist to hip ratio can be used to assess your risk of chronic diseases. If your belly is getting too big, it's probably fat, and abdominal obesity is associated with a higher risk cardiovascular disease, diabetes, some types of cancer and arthritis.

How to Measure Your Waist and Hips

Stand straight, but relaxed, in front of a mirror. Wear thin clothing or none at all. Place the measuring tape around your waist, close to your belly button. To measure your hips, place the measuring tape around the widest portion of your hips.

Men who have a waist circumference of more than 40 inches (102 centimeters) and women who have a waist measurement of more than 35 inches (88 centimeters) may have an increased risk of obesity-related diseases. 

The waist measurement can also be used along with the hips to determine your waist to hip ratio. Divide your waist circumference by your hip circumference to determine this ratio. Women who have a ratio above 0.8 and men who have a ratio above 0.95 may have an increased risk of obesity-related diseases.

What About Clothing Size?

Clothing size is determined by several body measurements, and it changes as you gain or lose weight. When you lose weight, your clothes start to feel loose and depending on how much weight you lose, they may not fit at all anymore. Or the opposite happens -- you gain weight, and your clothes become too tight. Then with a few more pounds, you go up a size. Or two or even more.

You can use a measuring tape to take several different measurements such as chest, waist and hips and compare them to size charts to determine your size.​

Using your clothes as an indicator can be quite motivating. It feels great to slide into those skinny jeans again, and you can see in the mirror how the fit of your clothes changes. But don't get too attached to a number. Clothing sizes vary considerably from one style of dress to another and even from one brand to another.


National Heart, Blood and Lung Institute. "Overweight and Obesity." Accessed March 15, 2016. http://www.nhlbi.nih.gov/health/dci/Diseases/obe/obe_whatare.html

American Heart Association. "What are Body Composition Tests?" Accessed March 15, 2016. http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Body-Composition-Tests_UCM_305883_Article.jsp#.Vt3FqZMrIUF.

Centers for Disease Control and Prevention. "About BMI for Adults." Accessed March 15, 2016. http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html

Després JP. "Body fat distribution and risk of cardiovascular disease: an update." Circulation. 2012 Sep 4;126(10):1301-13. Accessed March 15, 2016. http://circ.ahajournals.org/content/126/10/1301.full.

National Heart, Blood and Lung Institute. "Overweight and Obesity." Accessed March 15, 2016. http://www.nhlbi.nih.gov/health/dci/Diseases/obe/obe_whatare.html

National Institutes of Health. "Classification of Overweight and Obesity by BMI, Waist Circumference, and Associated Disease Risks." Accessed March 15, 2016. http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/bmi_dis.htm.

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