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Bioelectrical impedance analysis

Why get a body composition test?

 
The main reason to get a bio-electrical impedance analysis (BIA) test is to see how much of you is lean mass and how much is fat mass. Standing on the scales gives you your total mass (weight) but a BIA test will break down that mass into fat mass and lean mass (muscle, tendon, bone etc).
 
As BIA testing is affordable and quick, you can get regular tests and monitor your progress, or maintenance over time. This will let you see how well your dieting, hypertrophy training, new running club or whatever new thing you are adding to your life is affecting your body composition.
 
 

 

A body composition test will tell you your:
  • Body fat %
  • Lean mass %
  • Water content
  • Estimated Kcal requirements
  • Basal metabolic rate

 

 

Body composition pie chart
An example print out of body composition as a pie chart

How does it work?

Body composition is calculated using bio-electrical impedance analysis. Simply put, it sends an electrical current through your body. The machine measures the impedance (the amount of current your body stops passing through you) and calculates the percentage of fat, water and lean mass. A higher impedance means more fat% as electricity can pass through muscle much more easily as it has a higher water content.
Body composition analysis
An example print out of body composition in it's healthy ranges

Things to remember:

It works through impedance, so for most accurate measurements you should not eat or drink for 2 hours before your test.
 
You should also refrain from intense exercise as sweating will reduce you total body water, reducing the accuracy of the test.
 
It’s not only for top tier athletes, it’s not just for people who want to see their fat loss progress over time. Everyone can benefit from knowing what their body is made up of!
Bioelectrical impedance analysis

A body composition test will tell accurately and consistently how much of you is fat mass, and how much is fat free mass. It also works out how hydrated you are. Once it works this out, it can also tell you your kcal requirements  to maintain, reduce or increase your overall weight.

Whilst this testing is almost 100% accurate, it does rely on a few things. Firstly, you shouldn’t drink before the test. You shouldn’t play sport within 12 hours and you shouldn’t drink alcohol within 24 hours. The more of these you can check off, the more accurate your results will be.

This is because it relies on your bodies resistance to electricity. The machine sends a current from your foot to your hand and measures the difference. If you drink or eat before the test and it doesn’t get digested (hence 4 hours), it will bias the results. Alcohol dehydrates you so will inflate the fat mass estimate, the same reason why you shouldn’t exercise prior, because it dehydrates you. And a low water content will inflate your fat mass estimate.

This test is also relatively quick compared to other methods. It needs you to lay down for 5 minutes to let your bodies liquid level out then 2~ seconds for the test to run. So I like to repeat the test, which takes a couple more seconds to make sure the test is reproduced accurately and only then record those numbers.

 

References

 

 

1. Chula De Castro, J. A., Lima, T. R. D., & Silva, D. A. S. (2018). Body composition estimation in children and adolescents by bioelectrical impedance analysis: A systematic review. Journal of Bodywork and Movement Therapies, 22(1), 134–146. https://doi.org/10.1016/j.jbmt.2017.04.010