Friday I am going to have two different types of health assessment. In the morning, I will go to the Mena Medical Center to have blood drawn for testing. This is the “after” part of the 8 week walking program I have been participating in as a member of one of four teams from the college and numerous other teams from the community. Our campus wellness committee is paying for the blood work and I will report on it later. In the afternoon, I have an appointment with the Ouachita Rehabilitation and Fitness Center where I work out, to have skinfold body composition testing using calipers.
Body composition testing is intended to reveal the density of the body. The assumption is that there is a relationship between higher levels of body fat and disease conditions such as diabetes, heart disease and high blood pressure. I have written before about the Body Mass Index (BMI) which is a crude measure of body fat and is based on sedentary populations. The BMI is not appropriate for anyone who works out to build muscle, nor does it work on the extremely thin. Body composition analysis is a good way to track progress toward health during weight loss and/or fitness regimes. The recommended levels of body fat for men should range between 8-25 percent, and for women, 21-36 percent.
The most accurate way to measure body fat is to measure it after death, but by then, it’s too late. There are various methods to measure body fat, but the most accurate, on a living person, uses underwater or hydrostatic weighing. This isn’t always the most convenient method because the facilities for such testing are usually only available at research institutions and colleges or universities (not a small rural community college such as mine). Hydrostatic testing is based on the fact that bone and muscle are more dense (have more mass per volume unit) than fat. Fat floats in water so a body with more fat is lighter in the water. The accuracy of hydrostatic testing in vivo is +/- 1.5% error when compared with postmortem testing.
Skinfold Testing
Skinfold testing measures body density by taking measurements of how thick the folds of skin are at several points on the body using calibrated calipers. These measurements do not measure body density (or body fat) directly. Instead, they rely on the thickness of the fat in the skin fold and use equations that correlate with body density, and another equation that correlates with body fat. The body fat percentage is determined from the estimate of body density. Skinfold measurement correlates very well with hydrostatic testing, about .9, and has a standard error of about 3%. The BMI, on the other hand, has a much lower correlation of about .6. Skinfold testing is more convenient than hydrostatic testing and more accurate than simply using the BMI. Measurements are taken from either 7 points on the body, the 7 site skinfold test, or on three sites, the 3 site skinfold test. The 7 site test is slightly more accurate at predicting body fat with a hydrostatic correlation of .9 than the 3 site at .89. The sites that are measured are listed below.
7 site skinfold:
- chest
- triceps
- subscapular
- axilla
- suprailiac
- abdomen
- thigh
3 site skinfold (Men):
- chest
- abdomen
- thigh
3 Site Skinfold (Women)
- tricep
- suprailiac
- thigh
Here is my recap for the last few days.
| Calories | Protein | Carbohydrates | Sodium | Fat | % Calories from Fat |
| 1168.39 | 60.54 g | 194.88 g | 969.22 mg | 16.11 g | 12.01% |
| Calories | Protein | Carbohydrates | Sodium | Fat | % Calories from Fat |
| 1392.54 | 42.49 g | 242.79 g | 827.94 mg | 28.86 g | 18.32% |
| Calories | Protein | Carbohydrates | Sodium | Fat | % Calories from Fat |
| 1168.39 | 60.54 g | 194.88 g | 969.22 mg | 16.11 g | 12.01% |
