How To Tell If  You Have Healthy Body Composition -
Written by Greg Damian

Body composition is defined as the proportion of body fat to total weight. In addition to how poor body composition can make us look and feel, there are many adverse health outcomes related to poor body composition. A 2012 study found that people with a poor body mass index (BMI) had a weakened immune system. Being overweight can trigger immune reactions in the brain that disrupt memory and thinking. A 1999 study estimated that 280,000 people died in the U.S. annually as a result of obesity.

The situation has only gotten worse in the last 20 years. In the 2015-2016 survey, 18.5% of children and nearly 40% of adults were obese. These were the highest rates ever documented by the National Health and Nutrition Examination Survey.

How is body composition determined? The challenge is that there is no method, other than dissection, that can measure body fat exactly. So, every method for determining body composition is an estimate.

There are several methods available for estimating body composition and they all have advantages and disadvantages. The simplest body composition estimate is Body Mass Index (BMI). BMI is an indicator of body composition based on height and weight. It was developed in the 1830s by a statistician from Belgium. The calculation is simply a person’s weight (in kilograms) divided by their height (in meters) squared. Following this, my BMI is 63.63 kilograms / (1.65 meters x 1.65 meters) which produces a BMI of 23.4.

There are many online calculators that you can use to calculate your BMI. Knowing your BMI, the following guidelines are available to assess your body composition.

BMI Ranges and Body Composition Status

BMI Range

Body Composition Status

Below 18.5


18.5 – 24.9

Normal or Healthy Weight

25.0 – 29.9


30.0 and Above


Per the BMI Ranges and Body Composition Status table, my BMI of 23.4 is in the healthy range.

BMI has its critics and does not assess everyone correctly, especially heavyweight bodybuilders who have a disproportionate amount of muscle weight relative to their height.

Other methods for estimating body composition include:

  • DEXA scan equipment can be found in diagnostic centers and some doctor’s offices. DEXA uses an extremely low level of radiation to assess body composition.
  • Electrical impedance measurement devices are inexpensive and readily available. Body fat causes greater resistance (impedance) than lean mass and slows the rate of electric current which can be measured.
  • Hydrostatic weighing requires specialized equipment that is not commonly available.
  • Skinfold measurements can be performed using calipers by a trained person, often a personal trainer.

Some people consider hydrostatic weighing the gold standard of body composition measurements. I disagree based on my experience having measurements taken from all four methods. The secret is that hydrostatic weighing is difficult to do, not only because of the scarcity of tanks but also how difficult it is to perform the measurement. The subject must blow all air out of their lungs underwater which is not easy to do on command.

From any of these methods, a body fat percentage calculation is accurate within a couple of percentage points, but the results from different measurement methods will vary slightly.

As an example, within two weeks, I was measured at 8% body fat using a skinfold calculation, 10% on an electronic scale, and 12% from a DEXA scan. These results could be interpreted as if I gained body fat, when in actuality, I had not.

Use only one measurement method to monitor your body composition trend. If body fat measurements from your electronic scale, week over week, are 25%, 22%, 23%, 20% and then 19%, you know that you are trending lower.

Healthy body fat levels are different for adult men and women. The American Council on Exercise (ACE) offers the following guidelines:

ACE General Body Fat Percentage Categories

Women (% fat)

Men (% fat)

Essential Fat













32% +

25% +

If a 45-year-old man has a BMI of 33 and is measured at 34% body fat by DEXA and 30% by electrical impedance, then he can know that he has a poor body composition and should discuss this situation with his doctor. Note that it is possible, though difficult, to “swap” fat with muscle such that body weight does not change.

If your body composition is not where you want it to be, work with your healthcare team to create a SMART: Specific, Measurable, Attainable, Realistic, and Time-measured, goal and a plan that you can use to achieve your target body composition.

Gregory Damian is a Certified Personal Trainer and Sports Nutrition Advisor who holds three degrees and was enrolled in a Biomedical Engineering PhD program. You can find more about Greg, his published work and speaking engagements at
Ilavskáa, Silvia, et al. “Association between the human immune response and body mass index.” Human Immunology, Vol. 73, Issue 5, May 2012, Pages 480-485. doi: 10.1016/j.humimm.2012.02.023.
HBC2 Soleymani, MD, Taraneh. “Can My Weight Cause Memory Issues?” OAC Obesity Action Coalition, Summer 2017, Accessed 23 October 2022.
HBC3 Allison, D.B., et al. “Annual Deaths Attributable to Obesity in the United States.” JAMA. 1999, 282(16):1530–1538. doi: 10.1001/jama.282.16.1530.
HBC4 Hales, Craig M., et al. “Prevalence of Obesity Among Adults and Youth: United States, 2015-2016.” Centers for Disease Control, Prevention National Center for Health Statistics, October 2017,, Accessed 23 October 2022.
HBC5 Brazier, Yvette. “How useful is body mass index (BMI)?” Medical News Today, Reviewed 16 August 2017., Accessed 23 October 2022.
HBC6 “Calculate Your Body Mass Index.” NIH National Heart, Lung, and Blood Institute, Accessed 23 October 2022.
HBC7 “About Adult BMI.” CDC Centers for Disease Control and Prevention, Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, 29 August 2017, Accessed 23 October 2022.
HBC8 DuVall, Jeremey. “The 5 Best Ways to Measure Body Fat Percentage.”, 12 August 2014, Accessed 23 October 2022.
HBC9 Muth, Natalie Digate. “What are the guidelines for percentage of body fat loss?” ACE American Council on Exercise, 2 December 2009, Accessed 23 October 2022.
BmiBody compositionBody mass indexExerciseFatFat lossFat percentageFat vs muscleFitnessMeasuringStrengthWeight loss

1 comment

M Hertel

M Hertel

So much to love about this article. Solid recommendations about how to measure/track body composition and I like the addition of the general body fat percentage categories. If I wanted to nitpick, I’d point out that BMI is not a good indicator of an individual’s health markers, including immune system function. But I’m not denying BMI and immune system health are correlated in large population studies. And, all in all, I wish we had found this resource to include in our piece about the basics of body composition.

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