Measuring skinfolds for fat mass assessment: the ultimate guide

Using skinfolds for fat mass assessment can be a good way to assess your client’s health, but it can be difficult to get an accurate measurement. Here’s what you need to know about this method if you plan on using it in your practice. 

If your client is interested in gaining muscle mass or reducing their fat mass, then it’s recommended that dietitians look at body composition instead of the number on the scale. The scale doesn’t distinguish between fat, muscle, bones, or fluid, so it’s not going to be accurate when it comes to evaluating body composition.

There are a wide variety of methods that can help you get a deeper insight into your client’s body. These include DEXA scans, Bod Pods, skinfold assessments, and even BMI, and while they can be beneficial, these all come with their own unique set of errors. 

In this article, we will focus on skinfolds for fat mass assessment, as well as some common errors, and how to correctly use this method in your practice to better assess your client’s health.

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Main Skinfolds

We present below some practical information to measure the main skinfolds. The measurement of these skinfolds is necessary for the use of absolute predictive equations, described further ahead.

Triceps Skinfold

The triceps skinfold site should be marked on the posterior surface of the arm, on the midline of the triceps muscle, halfway between the acromion and radius.

The skinfold should be picked up parallel to the long axis of the arm. The subject should be standing, with their arms relaxed along the torso. The tester should be behind the subject, on their right side.

Subscapular Skinfold

The subscapular skinfold site is marked immediately below the inferior angle of the scapula.

The location of the skinfold should be marked 2cm below the subscapular skinfold site (by using an anthropometric tape), laterally and obliquely.

The skinfold forms a line of about 45 degrees (but it follows the skin’s natural fold lines), extending obliquely in the direction of the right elbow.

Biceps Skinfold

The biceps skinfold should be marked in the anterior surface of the arm, over the biceps, and halfway between the acromion and radius.

The patient should be standing, with their arms relaxed along the torso. The skinfold should be picked up vertically (parallel to the length of the arm).

Supraspinale Skinfold

The supraspinale skinfold is located in the intersection between two lines: the line that connects the Iliospinale point to the axillary’s anterior margin, and the horizontal line marked on the Iliocristale point.

Iliospinale point: anterior superior iliac spine point.

Iliocristale point: the most lateral point of the upper margin of the iliac crest.

The subject should be standing with their arms relaxed along the torso. They can also cross the right upper arm over the torso. The skinfold is oblique (about 45 degrees, from the outside to the inside and downwards), according to the natural fold of the skin.

Abdominal Skinfold

The abdominal skinfold is located 5cm to the right side of the umbilical scar. This distance should be measured with an anthropometric tape.

This distance is used for individuals measuring around 170cm. When the individual’s height differs greatly from this value, it is necessary to adjust the distance by applying the following formula:

Distance of the point to the umbilical scar = 5 x (Height / 170cm)

The patient should be standing, with their arms relaxed along the torso. The abdominal skinfold is measured vertically at the umbilical point.

Front Thigh Skinfold

The point should be marked halfway between the inguinal fold and the upper point of the patella, in the midline of the leg’s anterior surface.

The subject should be seated on the edge of a bench with an upright torso and the right leg extended. The hands should be under the thigh and exert upward pressure to reduce the tension of the skin. The left leg should be flexed, forming a 90-degree angle between the thigh and the leg.

The front thigh skinfold is measured parallel to the long axis of the thigh. Since this fold can be harder to point out, the tester may ask for the assistance of a third person, who raises the fold with both hands at about 6cm on either side of the marked site.

Medial Calf Skinfold

The medial calf point should be marked in the internal surface of the leg, at the level of the maximum circumference of the calf. To mark this point, the subject should be standing, with their arms relaxed along the torso, with their feet apart and the bodyweight equally distributed between both feet.

The tester should be positioned in front of the patient and look for the maximum circumference using an anthropometric tape. This horizontal line should be intercepted by a vertical line located in the middle part of the leg.

The subject should place their right leg in an anthropometric box and ensure there is a 90-degree angle between the thigh and the leg. The fold should be measured in the medial calf skinfold site, vertical to the length of the leg.

Iliac Crest/Suprailiac Skinfold

The iliac crest skinfold should be raised superior to the iliocristale, at the level of the line that connects the midpoint of the armpit to the ilium.

The skinfold is measured immediately above the iliac crest skinfold site. To do so, the tester should place the thumb over the iliac crest point and then measure the fold (it is taken near horizontally, but it follows the natural fold lines of the skin).

How can Nutrium help you?

Nutrium allows you to consolidate all the information and appointments of a patient in one place. If you use the body mass determined by a bioimpedance scale or by predictive equations, Nutrium will be useful.

In the first case, please note that by using an InBody bioelectrical impedance scale, you can automatically import all the measurements with one click. Read this article to learn more.

If you prefer to determine the body mass by using predictive equations, simply register the necessary skinfold measurement. Nutrium will automatically do the math. Here’s how to proceed:

1. In the Measurements tab, register the skinfold.

If the skinfolds do not show up in that tab, just click on the green button at the bottom of the page Configure measurement types.

2. After registering the necessary skinfolds, depending on the age and the level of physical activity of the subject, the software will automatically calculate the percentage of body mass, using one of those equations.