Designing a Body Composition Assessment Plan

Often when people think about a body composition test, they think: Client or Athlete arrives, a body composition test is performed, they get a printout of their results and then they are on their way.

Is it really this simple? Our view is that it shouldn’t be.

We recommend developing a Body Composition Assessment Plan. The Plan should consider: what is the Client’s goal, what assessment ‘method’ is most appropriate for this individual, what (if any) follow up testing will be done, and, since every method has some inherent error, what is the error rate for the chosen method? Let’s discuss each.

The client’s goal is important to consider when planning an assessment because the goal will help determine what test method is chosen. For example, if the client is interested in building bone, the best choice would be to use DXA, which gives bone, fat and lean mass. On the other hand, if losing fat in response to a weight loss effort is their goal, then a method that is both accurate for measuring fat and is reliable to detect changes would be the most appropriate. So, knowing the goal will help in choosing the correct method.

Another important factor to consider, when choosing a method, is whether the method is appropriate for the person being measured? Assessment methods are often ‘validated’ on certain populations so they are accurate when used on those populations and may not be as accurate for others. For example: there are skinfold equations validated for athletes, and there are different equations for non athletes. Differences in youth, adults and elderly clients can also be significant. Accuracy is also influenced by technician error. Technicians should acquire training and calculate their technical error of measurement (TEM) for the methods they use. Drop us a note if you’d like to know how to do this. Appropriate training and a full knowledge of the strengths and weaknesses of body composition methods are important in choosing a method.

Finally, a few other important factors that can affect accuracy over time are:

• Hydration level
• Time of day
• Time since last meal

So, in summary: a Body Composition Assessment Plan

• Should be individualized for a client.
• Include a statement of the client’s goal.
• Employ the most appropriate assessment method.
• Use a ‘protocol’ to perform the measurement to improve reliability.
• Standardize the actual protocol, the pre-test conditions, and the client preparation.
• A plan should include detailed documentation in the event a different technician performs the follow-up measurement.
• A calculation of the TEM for the chosen method.
• A plan for the length of follow-up.

A Body Composition Assessment Plan ensures that you are choosing the right method given the client’s goals and that measurements are made with the lowest possible error. Everyone who makes body composition measurements should have a plan! Do you have a plan?