Skinfold Thickness Measurements

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Definition




Skinfold Thickness Measurement is an essential methods used for anthropometric assessment of body composition. This quick and noninvasive method requires a minimal number of tools to calculate the total body fat.[1]

Relevant Characteristics




A skinfold thickness measurement provides an estimated size of the subcutaneous fat deposit, which is basically the fat under the skin. By estimating the thickness of this area, researchers are able to obtain an estimation of the total body fat. The goal of this method is to provide an assessment of adiposity, which is a better method than the Body Mass Index (BMI). Researchers in different disciplines can use this method to analyze the malnutrition of a specific individual, group, or population. Since fat is considered one of the main sources of energy, a large and rapid loss of body fat is indicative of severe negative energy balance [1]. However, small changes in the body fat- for example less that 500 grams- cannot be assessed using anthropometry. This method can also provide an association between body fat, disease, and illness, which result from undernutrition.

Skinfold thickness measurements can be used in clinical settings or in the field. There is no limited or required sample size involved in the method; however, if the research involves a population or a clinical study, the recommended sample size can be 10 times as many participants as variables to obtain statistical significance.[2] This method is considered one of the more reliable methods in accessing body fat, compared to other anthropometric measurements. As stated by Brewis (2011), skinfold thickness measurements are standard practice in assessing nutritional status by bio-cultural anthropologists, nutritional anthropologists, and human biologists who engage in fieldwork.


"Method Made Easy”




The only tool needed for this method is the precision thickness caliper. There are three different types of calipers that can be used: Harpenden, Lange, and Holtaino [1]. These calipers usually are costly. Low-cost calipers are also available; however, they tend to have a lower precision and accuracy.

To begin the assessment, skin is pinched using both the index finger and measured at the following five skin fold sites:Triceps, Biceps, Subscapular, Suprailiac, and Midaxillary. To measure those skinfold sites, the participant would stand up, with relaxed shoulder and arms hanging freely at the sides. According to the National Health and Nutrition Examination Survey (NHANES), the measurement of the skinfold site should be on the right side of the participant. Lohman et al. (1988) had described in detail the steps in taking the measurements of those five sites[3]

The following steps are necessary to obtain the final value of the body fat percentage or total body fat (kg):

  1. After obtaining all the skinfold sites measurement, the choices of the most appropriate sites depends on the age, sex, and race of the subject, and whether the researcher wanted to estimate the body fat percentage or total body fat.
  2. After choosing the appropriate sites for the study, an equation will be used to calculate the body density using either population-specific regression equations or generalized regression equations.
  3. The sum of the choice skinfold will be used in the regression equations to obtain the body density.
  4. Finally, an equation will use the body density to calculate the total body fat. In this last step, there are three different equations that can be used that all yield approximately similar results.

Male Body Density and Percentage Body Fat


There are different formulas used to calculated Body Density (BD) and Percentage Body Fat (%BF). Formula vary according to the gender of the participant and the number of skinfold sites. Below is formula for three-sites:[4]

Male Three-Site Formulas

(Chest, Abdomen, Thigh)
BD = 1.109380 – (0.0008267 × sum of three skinfolds) + (0.0000016 × [sum of three skinfolds]2) – (0.000257 × age)

(Abdomen, Suprailiac, Triceps)
%BF = (0.39287 × sum of three skinfolds) – (0.00105 × [sum of three skinfolds]2) + (0.15772 × age) – 5.18845

Female Three-Site Formulas

(Triceps, Suprailiac, Thigh)
BD = 1.0994921 – (0.0009929 × sum of three skinfolds) + (0.0000023 × [sum of three skinfolds]2)– (0.0001392 × age)

(Abdomen, Suprailiac, Triceps)
%BF =(0.41563 × sum of three skinfolds) – (0.00112 × [sum of three skinfolds]2) + (0.03661 × age)+ 4.03653


Advantages




Skin thickness measurements can be obtained quickly and easily with inexpensive tools. If preformed precisely, skinfold thickness measurements are a highly accurate means of assessing total body fat percentage.


Limitations




The first and most important limitation is within-examiner error. Within-examiner errors occur when the same examiner obtains different results on a participant or subject. For example, the within-examiner errors occurs when the examiner has a minimal experience in taking skinfold measurements. Another within-examiner error may occur if the participants is relatively obese.

A second limitation is the between-examiner error. This type of error arises when two or more examiners obtained different results on the same subject and skinfold sites. [1] Another limitation is that the total body fat cannot be obtained from one single skinfold site measurement. According to Siervogel et al. (1982), the measurement of the triceps skinfold is the more representative site for total body fat. However, for adult males and females, the most representative skinfold site is the subscapular and midaxilary sites[5] Therefore, this method requires a multiple skinfold measurement, and researchers cannot depend on one site measurement. The method also requires some touching and skin exposures, which may make certain subjects uncomfortable.

Analysis




The World Health Organization has proposed the cut-off point for body fat percentage in adult men and women. The definition of obesity is a

body fat percentage in excess of 25% in men and 35% in women [5]. Although these cut-offs are debatable, the percentage of body fat cutoffs are within the range of 20-25% in men and 30%-35% in women, which can determine the risk of metabolic disease and cardiovascular diseases related to overweight and obesity[6]

Method in Context




The skinfold method can distinguish between fat and fat-free mass. The body consists of two chemically different components, the fat and fat-free mass, which refers to the skeletal muscle, non-skeleton, and soft lean tissues. The average fat content of women is higher than men. Women's fat content usually represents 26.9% of their total body weight compared with 14.7% in men. The body fat is deposited in two major types of sites one for the essential lipids that found in bone marrow, central nervous system, glands, and organs, and the second is fat storages that consists of inter and intra-muscular fat, GI track, and subcutaneous fat. One third of the total body fat is estimated to be in the subcutaneous fat[1]


Online Resources




References


  1. ^ Gibson, Rosalind S. 2005 Principles of nutritional assessment. New York: Oxford University Press.
  2. ^ Field, Andy P. 2009 Discovering statistics using SPSS: (and sex, drugs and rock 'n' roll). Los Angeles: SAGE Publications.
  3. ^ Lohman TG, et al 1988 Anthropometric Standardization Reference Manual. Human. Kinetics, Champaign, IL.
  4. ^ Guidelines for Exercise Testing and Prescription:American College of Sports Medicine. 2000. Philadelphia : Lea & Febiger, 6th ed.
  5. ^ Siervogel, R. M., et al. 1982 Subcutaneous fat distribution in males and females from 1 to 39 years of age. Am J Clin Nutr 36(1):162-71.
  6. ^ Oreopoulos, Antigone et al.2011 More on Body Fat Cutoff Points. Mayo Clinic. June: 86(6):584-587.