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Skinfold Formula Description

This method estimates body fat percentage based on skinfold thickness measurement at specific anatomical sites. The formula used is often specific to the gender and may be part of a more extensive set of formulas for various populations. Here's a detailed description of how the skinfold formula works:

Components of the Formula:

  • The sum of Skinfold Thicknesses: This variable represents the sum of skinfold thickness measurements taken at specific anatomical sites on the body. These sites commonly include the triceps, biceps, subscapular, supra iliac, abdominal, front thigh, and medial calf.
  • Gender: The consideration of gender in formulas for estimating body fat percentage, particularly those derived from skinfold measurements, is based on observed differences in fat distribution patterns between males and females. Men and women tend to store body fat in different areas and exhibit variations in fat distribution, even at the same overall level of body fat percentage.

Skinfold Formula Description

This method estimates body fat percentage based on skinfold thickness measurement at specific anatomical sites. The formula used is often specific to the gender and may be part of a more extensive set of formulas for various populations. Here's a detailed description of how the skinfold formula works:

Components of the Formula:

  • The sum of Skinfold Thicknesses: This variable represents the sum of skinfold thickness measurements taken at specific anatomical sites on the body. These sites commonly include the triceps, biceps, subscapular, supra iliac, abdominal, front thigh, and medial calf.
  • Gender: The consideration of gender in formulas for estimating body fat percentage, particularly those derived from skinfold measurements, is based on observed differences in fat distribution patterns between males and females. Men and women tend to store body fat in different areas and exhibit variations in fat distribution, even at the same overall level of body fat percentage.

Measurement Points:

The seven measurement points used in skinfold thickness are specific anatomical sites on the body where the thickness of subcutaneous fat is assessed using a skinfold caliper. These measurements are often part of formulas to estimate body fat percentage. Here are the details of the seven measurement points:

  • Triceps Skinfold:
    • Location: The back of the upper arm, halfway between the shoulder and elbow.
    • Procedure: The skinfold is pinched vertically, and the thickness is measured.
    • Purpose: Reflects fat stores on the back of the upper arm.
  • Biceps Skinfold:
    • Location: The front of the upper arm, at the same level as the triceps site.
    • Procedure: Similar to triceps, the skinfold is pinched vertically, and the thickness is measured.
    • Purpose: Assess fat stores on the front of the upper arm.
  • Subscapular Skinfold:
    • Location: Just below the bottom tip of the shoulder blade (subscapular region).
    • Procedure: The skinfold is pinched diagonally below the shoulder blade, and the thickness is measured.
    • Purpose: Reflects fat stores on the back, particularly near the shoulder blade.
  • Suprailiac Skinfold:
    • Location: Just above the hip bone on the side of the body (supra iliac crest).
    • Procedure: The skinfold is pinched diagonally above the hip bone, and the thickness is measured.
    • Purpose: Assess fat stores on the side of the torso.
  • Abdominal Skinfold:
    • Location: Approximately one inch to the side of the navel.
    • Procedure: The skinfold is pinched vertically to the side of the navel, and the thickness is measured.
    • Purpose: Reflects fat stores around the abdominal region.
  • Front Thigh Skinfold:
    • Location: The front of the thigh, halfway between the hip and knee.
    • Procedure: The skinfold is pinched vertically on the front of the thigh, and the thickness is measured.
    • Purpose: Assess fat stores on the front of the thigh.
  • Medial Calf Skinfold:
    • Location: The inner side of the calf, at the maximum circumference.
    • Procedure: The skinfold is pinched vertically on the inner side of the calf, and the thickness is measured.
    • Purpose: Reflects fat stores on the inner side of the lower leg.

Considerations:

  • Bilateral Measurements: It is expected to take skinfold measurements on both sides of the body and calculate the average to account for potential asymmetry.
  • Technique: Proper technique is crucial for accurate measurements. The skinfold should be pinched firmly but not aggressively, and the caliper should be applied perpendicular to the fold.
  • Professional Assistance: While skinfold measurements can be done independently, having a trained professional conduct the measurements can enhance accuracy.

How the Formula Works:

Skin Measurements:

Skinfold thickness measurements are taken at specific anatomical sites using a skinfold caliper. These measurements represent the amount of subcutaneous fat beneath the skin.

Summation:

The individual skinfold thickness measurements are summed to get the total skinfold thickness (skinfoldSumskinfoldSum).

Calculation:

The formula involves three terms: a linear term 

bodyFat = 0.29288 × skinfoldSum - 0.0005 × skinfoldSum^2 + 0.15845
  • The linear term represents the contribution of skinfold thickness to body fat.
  • The quadratic term captures the potential nonlinear relationship between skinfold thickness and body fat.
  • The constant term adjusts the formula to align with reference methods or to correct biases.

Gender Differentiation:

The formula includes a conditional statement to differentiate between males and females. This differentiation accounts for known differences in body fat distribution and the relationship between skinfold thickness and body fat in different genders.

Output:

The result (bodyFatbodyFat) estimates the individual's body fat percentage based on skinfold thickness measurements.

Considerations:

  • Empirical Basis: The formula is based on empirical studies and statistical analyses of population data. It may have been derived through regression analysis, where the relationship between skinfold measurements and body fat percentage is modeled.
  • Limitations: Skinfold measurements indirectly estimate body fat percentage and are subject to variations. The accuracy depends on factors such as the examiner's skill and adherence to standardized measurement protocols.
  • Population-Specific: The formula and coefficients may be specific to a particular population, and different formulas may exist for other demographic groups.
  • Professional Interpretation: Interpretation of the results should be done in consultation with trained professionals, as they can provide insights into individual variations and potential limitations of the method.

While widely used, this method is just one of many techniques for estimating body fat percentage. Consulting with healthcare or fitness professionals and considering multiple measurement methods is recommended for the most accurate assessments.