Body Composition Test

A body composition test is useful if you’re trying to lose weight, put on muscle mass or just improve your sporting performance.

Knowing your body composition can also help if you want to see the effect of different types of training, nutritional interventions or supplement use on body fat and muscle mass levels.

Athletes will use this information to help them understand performance and to determine their optimal body composition for competition. They can then adjust training and nutrition to ensure optimal body composition for their key competitions.

A body composition test is particularly useful for someone taking part in a weight-limited sport to ensure appropriate strategies for meeting body mass requirements.

There are several different ways your body composition can be assessed. These vary greatly in their accuracy, information they give you and ease of access. The one most suitable for you will depend on what information you want to find out and how detailed you need this information to be.

The main methods of measuring body composition are:

  • Skinfold calipers
  • Under-water weighing
  • Bioelectrical impedance
  • Dexa scanner
  • Bod pod

Please note, here at Loughborough University's Sports Science Service we only offer body composition assessments using the skinfold caliper method.


Skinfold Calipers

This involves using callipers to measure the thickness of skinfolds at several sites around the body. When carried out by a qualified, experienced practitioner this is an accurate way of assessing body composition.

body composition test



The International Society for the Advancement of Kinanthropometry (ISAK) has developed international standards for anthropometric assessment and an international anthropometry accreditation scheme. Someone who has an up-to-date ISAK qualification should provide an accurate assessment.

Bear in mind that someone who isn’t qualified or very experienced is likely to have quite a lot of variation in the their measurements – therefore not giving you an accurate reflection of your body composition.

Ideally skinfold measurements should not be taken immediately after training, competition, swimming, showering or sauna use. This is because these all increase blood flow to the skin which could result in increased skinfold thickness.

How Are Measurements Carried Out?

Landmarks are made on the body to mark where the measurements are taken. Landmarks are identifiable skeletal points. They are found by palpation or measurement. Commonly 7 or 8 sites are used (triceps, subscapular, biceps, supraspinale, abdominal, thigh, calf, iliac crest)

A skinfold is a double fold of skin plus the underlying adipose (fat) tissue.

What Information Do You Get?

The results can be presented as a sum of skinfolds (number in millimetres) or this can be converted into a percentage body fat. Most practitioners working with sports people will present the results as a sum of skinfolds. This is because there are many equations that can be used to determine percentage body fat.

These have been developed through research on different populations of people and use different numbers of skinfold sites. So you can put the same skinfold measurements into the different equations and get very different percentage body fat results. So by just presenting the results as a sum of skinfolds any potential distortion of the results is eliminated.

The sum of skinfolds can be compared to normative values however it is important to remember that everyone has their own optimal value and what is good for one person might not be good for another.

Underwater Weighing

Also known as hydrostatic weighing. This is based on the principle of water displacement.

How Are Measurements Carried Out?

This method can be very accurate however it is not very simple to carry out as it involves being weighed underwater. Usually multiple measures are taken to ensure accuracy. It requires the person to breathe out as much air from their lungs as possible before being submerged momentarily whilst their weight is measured.

What Information Do You Get?

The difference between an individual’s body mass ‘on land’ and that measured under water, when corrected for the density of water equals the body’s volume. Percent body fat is calculated from body density (the ratio of body mass to body volume.

Bioelectrical Impedance

How Are Measurements Carried Out?

Bioelectrical impedance analysis works by placing electrodes on the hands and feet and then a painless electrical signal is passed between them.

What Information Do You Get?

The resistance (impedance) to the flow of the signal is determined. Fat-free mass contains a high proportion of the body water and conducting electrolytes. Therefore the electrical current moved more easily and quickly through the fat-free mass than the fat mass.

So the amount of current flow through the tissues is related to the amount of fat in the tissue. This information is then used to calculate body density, which can then be converted to a percentage body fat.

Bioelectrical impedance analysis is easily carried out however its drawback is that your hydration status will affect the results.

Changes in hydration levels alter the body’s electrolyte concentration. Loss of body water means that the impedance value will be decreased resulting in an apparent lower percentage body fat, whereas increases in body water results in an apparently higher percentage body fat.

Also, skin temperature can affect the results.

This is a simple body composition test however the results are affected by an individual’s hydration status. As such this is not the ideal method of body composition assessment.

Dexa Scanning

Dexa stands for Dual Energy X-ray Absorptiometry.

How Are Measurements Carried Out?

The assessment is straight forward. The individual lies on an open ‘table’ whilst their body is scanned for around 8 minutes. Two x-ray beams with different energy levels are used to scan the body. One of the energies is absorbed more by fat than the other.

What Information Do You Get?

Specialised computer software is used to construct an image of the underlying tissue, and quantify body composition. It is most commonly used for measuring bone density, but also provides information on bone mineral, total fat mass, lean mass and muscle mass.

This method is often described as the gold standard of clinical body composition analysis, producing accurate, reliable results.

Bod Pod

The Bod Pod uses patented Air Displacement Plethysmography to determine percentage body fat.

How Are Measurements Carried Out?

It is a simple assessment and involves sitting inside a Bod Pod chamber for around 5 minutes. The individual’s body mass is measured and their body volume is calculated whilst they are in the chamber.

What Information Do You Get?

Body mass and body volume are used to calculate body density, and the percentage body fat and lean body mass.


Summary Of Body Composition Test

Body composition can be affected substantially by diet and exercise. A body composition test can help you determine the optimal body compositionr sporting performance or help you understand the impact of your diet and exercise on your body make-up.

There are a range of methods for assessing body composition, and they y in their ease of use and accuracy

Here at Loughborough University Sports Science Service we offer body composition tests with the use of nfold calipers

All staff are ISAK qualified. If you would like to make an appointment for a body composition test please contact us.


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