Sherrie Hebert

You could be pinched, dunked, have electrical currents run through your body or take a spin on a merry-go-round. Mean bully? Weird carnival? Bad dream? Maybe so, but not here. They are methods used to measure body composition. Your body composition is the ratio of fat mass to non-fat mass, which includes muscle, bone and water. Measuring body composition is one of the most effective ways to define and monitor your health and fitness goals and is done using various methods, including those above. But isn’t that what my BMI measures?

Body Mass Index, or BMI, has been around since the early nineteenth century with the purpose to determine whether one is at a healthy weight. BMI is calculated by dividing your weight in kilograms by your height in meters squared, then ranking your health based on the following:

Underweight: Less than or equal to 18.5

Normal weight: Between 18.5 and 24.9

Overweight: Between 25 and 29.9

Obesity: 30 and greater

Even though your BMI is a simple calculation, the results are misleading. For example, a 5 foot-6 inch, 150-pound female has a BMI of 24.2, lying in the healthy range. However, if that same person has much greater muscle mass weighing 165 pounds, her BMI would be 26.6, putting her in the overweight category. Thus, the formula disregards the ratio of lean muscle mass to fat mass.

Measuring your body composition is best done with more than a calculator. The techniques below are the most common methods with more realistic representations of your body composition along with the following general body fat ranking percentages.

Essential body fat: Women 10 to 12 percent; Men 2 to 4 percent. (It is extremely dangerous to drop below the essential fat values)

Athletes: Women between 14 and 20 percent; Men 6 to 13 percent

Fitness: Women between 21 and 24 percent; Men 14 to 17 percent

Acceptable: Women between 25 and 31 percent; Men 18 to 25 percent

Obese: Women 32 percent and above; Men 25 and above

Body circumference, aka the tape measure method, measures body circumferences to estimate body fat and is inexpensive, quick and simple to learn. Skinfold calipers are used to pinch subcutaneous fat, which is the fat underneath the skin, in three to seven specific sites on the body, varying between men and women. Calipers are inexpensive and take little time to learn, however accuracy depends upon the skill of the person taking the measurements. With both the circumference and caliper methods simple to use and readily available, they are preferred for monitoring the progress of body composition changes.

Dual-Energy X-ray Absorptiometry (DXA) is used to assess bone density but also measures fat and lean mass with little error. Only physicians perform the scans, thus are very expensive and done infrequently making them unfit for evaluating progress.

Hydrostatic weighing, also known as underwater weighing, estimates body composition while under water to determine your body’s density. It is accurate and quick yet is often only available in research facilities. Additionally, some people prefer not to be submerged or they are unable to hold their breath long enough to complete the assessment.

Bioelectrical Impedance Analysis (BIA) detects how your body responds to small electrical currents from electrodes on your skin. Electrical currents move through muscle easier than fat, providing relatively accurate results. BIAs are available to consumers but are less accurate than those used in medical and research facilities. Bioimpedance Spectroscopy (BIS) and Electrical Impedance Myography (EIM) also use electrical currents to measure body fat. BIS devices are unavailable for purchase and primarily used in research and medical facilities. Inexpensive EIM devices are available to purchase yet are less accurate.

3-D Body Scanners use infrared sensors to get a three-dimensional look at your body shape taken from millions of points on your body. Scan data then generates body fat and muscle mass and provides a visual posture analysis that may provide guidance for training methods. Some scanners have you stand on a rotating platform, while others rotate around your body. Scanners take little time, are fairly accurate and may be used often to evaluate progress.

The availability of body composition measuring methods in Southeast Idaho is comparable to larger cities. The least expensive and best methods for consistent evaluation of body composition changes are skinfold calipers and body circumference with a tape measure. As 3D scanners gain in popularity, they, too, will provide consistent body fat analysis.

Measuring your body composition is key to beginning a health and fitness program. Initial measurements will help to establish your goals, then scheduled measurements will mark your progress. As a personal trainer, I regularly measure body composition using tape measure, calipers and 3D scanner methods. Whether you are beginning or currently in a health and fitness program, or just curious, send an email or call to schedule an appointment to measure your body composition, with your initial visit at no charge.

And the fun part? You get to ride a merry-go-round and be pinched!


Healthline “Body composition: Health and Performance in Exercise and Sport,” ​ Henry C. Lukaski

Sherrie Hebert is a certified personal trainer and Pilates mat and equipment instructor. She teaches and trains at Performance Pilates and Gold’s Gym of Pocatello. Contact her at 208-317-5685 or for all your health and wellness needs.