Body Composition - What You Need to Know About Body Composition

Body fat monitor
Body fat monitor. Lebazele/Getty Images

When we talk about losing weight, what we really mean is losing body fat. After all, it's the fat we want to get rid of while preserving muscle mass, which is more metabolically active than fat.

That's where the term body composition comes in. Body composition refers to how much body fat you have as opposed to lean muscle tissue. The more lean muscle tissue you have, the healthier you are and, of course, the better you feel and look.

It may surprise you that lean muscle tissue doesn't just include your muscles. It also includes all your bones and organs as well. 

Meanwhile, fat tissue is composed of three different types of fat: Essential fat, or what your body needs to continue to function, storage fat and, our least favorite non-essential fat. It's that non-essential fat that we most want to get rid of, but it's also the most stubborn.

Factors That Determine Your Body Composition

Body composition isn't just determined by our genetics and, in fact, there are ways to change body composition. By doing cardio on a regular basis, strength training for the entire body and eating a healthy low-calorie diet, you can change your ratio of fat to muscle.

However, there are factors we can't control that may affect body composition:

  • Age - As we get older, unfortunately, metabolism slows down and we can also start to lose muscle mass if we don't maintain that muscle with weight training.
  • Gender - Women tend to have more body fat than men because we need that extra fat to nourish babies during and after pregnancy.
  • Genes - Your parents and other relatives are responsible for at least some of your body composition.
  • Hormones - If you're a woman who's gone through perimenopause or menopause or you've had any thyroid issues, you've likely experienced how hormonal changes can also change your body composition, usually for the worse.


    Measuring Your Body Composition

    There are a number of ways to measure body fat. Some require visiting some sort of facility, a gym or a lab, and paying to have the measurement done. That's your best bet if you want the most accuracy.

    However, there are other options that will give you a sense of your general body fat, even if it isn't as accurate as some of the other body fat tests. 

    • Bioelectrical Impedance - This is a painless test that measures how quickly an electrical current travels through the body. You typically hold a scale in both hands or stand on a scale and the current moves through your body. The more body fat you have the harder it is for that current to get through the body. This test can change based on your hydration levels, among other things, so you always want to take this test under the same circumstances every time. 
    • DEXA Scan - This is like an x-ray and one your doctor may order to check bone density as well.
    • Hydrostatic Weighing - This is considered the gold star of body fat measurement.  It's an underwater test that you can sometimes find at universities or labs. It's also more unpleasant. You are dunked underwater where you blow out your breath so experts can measure your body fat.
    • Skinfold Measurements - For this, a personal trainer or expert uses calipers to take skinfold measurements at different parts of the body. This one can also be affected by the person taking the measurements - You want them the exact same place every time, which is difficult.
    • Body Fat Calculator - This probably the least accurate, just because it doesn't take into account all the factors that affect body fat, but it can give you a number to measure on a regular basis to track your progress.

    How to Burn Body Fat

    The question becomes, how do you get rid of that extra, non-essential fat? There's exercise, of course, but how much exercise and what kind do you need?

    It depends on a wide variety of factors, but in general, if you want to lose weight you need to burn about 1500 to 2000 calories a week with both cardio and strength workouts.

    To see some sample workout schedules and more information about burning fat, find out How Much Exercise You Really Need.

    One more thing. Too often we worry about the number on the scale, but your body composition or body fat measurement is much more important. The scale can drift higher or lower all day long and you don't know what you're gaining or losing.

    However, you can easily lose body fat and the scale may not even notice. Maybe your weight didn't go down, but you're slimmer and you've lost inches. That's really what counts. Try using body measurements to track your weight loss progress or using the same pair pants each month. Try them on to see how they fit and you'll have a better idea whether you're making progress.

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