Why Measure Body Fat?
Body fat measurement is an import indicator of not only fitness level but also is an import predictor of future health risks.
A person’s weight does not give a clear indication of the health of that individual. The reason is that weight does not take into account the composition of that person in lean body mass (muscle) versus fat.
A person who carries too much body fat is at higher risk for many different types of health conditions. These obese individuals have a higher risk of developing serious health conditions such as: type 2 diabetes, heart disease, cancer, joint problems, stroke, osteoarthritis, skin problems, high blood pressure, sleep apnea, infertility, depression, and metabolic syndrome. That being said, there is a fairly wide range of body fat that a person can have and still be considered healthy.
How to Measure Body Fat
There are many different ways to measure your body fat. There are simple ways that you can do at home to other ways such as the DEX analysis that is very expensive and can only been done at laboratories and hospitals. If you’re looking to do testing at home, the two easiest and cost-effective options are the skinfold test and bioelectrical impedance analysis.
Skinfold Test
Body calipers are used to measure the thickness skinfolds at different sites across the body to estimate body fat percentages. These sites are:
Supra-iliac, Triceps, Bicepsk, Sub-scapular, Thigh, Abdomen, Chest, and the Mid Auxiliary.
Depending upon what type of skinfold caliper you purchase you may only need to take 3-4 site readings to get your measurement of body fat. The two types of skinfold calipers sold are digital skinfoldcalipers and manual skinfold calipers. Some of the digital calipers will also instantly show your body fat percentage without the need for you to add numbers and consult a chart.
Pro’s – the skinfold calipers are affordable and the measurements are easy to do.
Con’s – you need someone else to help you take the measurements and the chance of error is high due potentially measuring in the wrong places.
Bioelectrical Impedance Analysis (BIA)
A small (harmless) electric current is passed through the body. The electric current travels at different speeds through lean body mass (muscle), body fat and skeletal tissue. Muscle contains more water than fat and therefore is a better conductor of the electric current. Please note that the BIA doesnt’ actually measure body fat but rather the density of your body. The BIA machines have built in formulas that calculate your body fat percentage based on your body density readings. Even though you will not get your ‘true’ body fat percentage, you will get results that are accurate within 10-15% (depending upon model of device). BIA is available in laboratories or at home in the form of scales and hand-held body fat analyzers.
Pro’s – simple, safe, cost effective, and if done at home you don’t need anyone to help you.
Con’s – the user’s level of hydration affects the accuracy of this test, men and women store fat differently (abdomen versus hips) which can make the results less accurate for total body fat percentages, different machines can produce different results.
Dual energy X-ray absorptiometry (DEXA Scan/DXA)
The DXA is the current ‘gold’ standard for body composition results and is a very accurate way to measure body fat. This scan will give you an accuracy within 3-4%. It is commonly used for bone density scans but can also produce body fat readings as well. DXA uses two different types of X-rays to scan the body. One scans for all body tissue, while the other can’t detect body fat. A computer compares the two images and body fat percentage is calculated.
Pro’s – accuracy
Con’s – cost ($100 + per scan), located in hospitals and laboratories
Water Weighting
This is another accurate method of estimating body fat. The subject is submerged under water and weighed while expelling air from their lungs. This method relies on the displacement of water and the different composition (density) of lean body mass and body fat.
Pro’s – accuracy
Con’s – due to the nature of the test, it is limited to research facilities, cost
Height and Circumference Methods
There are a few different formulas that exist that compare a person’s weight to girth measurements. From these you can estimate body fat percentages. We won’t get into them here as they are not as accurate as the techniques described above.
Interpretation of Body Fat Results
When you calculate your body fat percentage you have to look at a few different body fat charts to help interpret your results. There is the basic overview and then the age-related body fat chart. In general, body fat percentages over 25% in men and 32% in women increase health risk. These percentages are independent of weight.
Body Fat Charts
Here is a body fat chart by the American Council for Fitness:
| Women | Men | Classification |
| 10-12% | 2-4% | Essential Fat* |
| 14-20% | 6-13% | Athlete |
| 21-24% | 14-17% | Fitness |
| 25-31% | 18-25% | Acceptable |
| >32% | >26% | Obese |
*Essential Fat is the lowest level of body fat that is necessary for your body to function properly. A small amount of fat is necessary to fuel the body in time of need.
| Age-Adusted Body Fat Percentage Recommendations | ||||
| Women | ||||
| Age | Underfat | Healthy Range | Overweight | Obese |
| 20-40 yrs | Under 21% | 21-33% | 33-39% | Over 39% |
| 41-60 yrs | Under 23% | 23-35% | 35-40% | Over 40% |
| 61-79 yrs | Under 24% | 24-36% | 36-42% | Over 42% |
| Men | ||||
| Age | Underfat | Healthy Range | Overweight | Obese |
| 20-40 yrs | Under 8% | 8-19% | 19-25% | Over 25% |
| 41-60 yrs | Under 11% | 11-22% | 22-27% | Over 27% |
| 61-79 yrs | Under 13% | 13-25% | 25-30% | Over 30% |
| Source: Gallagher et al. Am J Clin Nut 2000; 72:694-701 | ||||
