Question 1

What is the skinfold (Jackson-Pollock) method?

Accepted Answer

The Jackson-Pollock 3-site skinfold method estimates body fat percentage by measuring the thickness of subcutaneous fat at three specific body sites using a caliper. These readings are used to calculate body density, which is then converted to body fat percentage via the Siri equation. The method was developed and validated by Andrew Jackson and Michael Pollock in 1978 and is widely used in exercise science research and practice.

Question 2

Why is skinfold considered the gold standard among field methods?

Accepted Answer

Skinfold testing directly measures subcutaneous fat at specific body sites rather than relying on proxy measurements like circumferences. When performed by a trained technician with accurate calipers, skinfold correlates closely with DEXA and hydrostatic weighing — the laboratory reference standards. It also accounts for sex and age differences in fat distribution, which circumference-based methods handle less precisely.

Question 3

What is the difference between 3-site and 7-site skinfold?

Accepted Answer

The 3-site Jackson-Pollock method (used here) measures three body sites and is faster and practical for regular self-monitoring. The 7-site version adds four additional sites (subscapular, midaxillary, suprailiac, and triceps for men; chest, subscapular, midaxillary, and abdomen for women) for a more comprehensive picture. Research suggests the 3-site and 7-site protocols produce similar results when measurements are taken correctly.

Question 4

How do I take accurate skinfold measurements?

Accepted Answer

Grasp the skin and underlying fat between your thumb and index finger approximately 1 cm above the measurement site, then apply the caliper jaws at the site itself. Read the caliper after about 2 seconds to let the jaws stabilize. Take each measurement twice and average the two readings. Measure on the right side of the body, avoid measuring immediately after exercise or bathing, and maintain consistent technique across sessions to ensure comparable results over time.

Question 5

Can I do skinfold measurements on myself or do I need help?

Accepted Answer

The chest and abdomen sites are difficult to measure on yourself with consistent technique. The thigh site can be self-measured but is easier with a partner. For the most reproducible results — especially if you are tracking changes over time — having the same trained person take measurements each time is ideal. That said, self-measurement with care can provide a reasonable estimate for general monitoring.

Question 6

How accurate is skinfold compared to DEXA or hydrostatic weighing?

Accepted Answer

In trained hands, the Jackson-Pollock 3-site method produces results that correlate closely with DEXA and hydrostatic weighing. Measurement error increases with poor technique, inconsistent site location, or calipers that are worn or poorly calibrated. The method tends to be less precise at very high or very low body fat levels, where fat distribution patterns differ from the populations used to develop the formula.

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