Should You Test Your Body Fat?

Body fat testing has gained popularity and accessibility over the years but do you really need to test your body fat? Is this something that you need to focus on or is it just extra noise in the background?

Why are you getting your body fat tested?

Who is testing it?

What methods are being used and what are you comparing it to?

Can you look at this test like a data point or is it going to do more harm than good?

These are all important questions to answer and know before you decide to get a test done. And while understanding the different methods is important, what’s even more important is knowing how to get predictable results and what you can learn from body fat testing.

First, let’s dive into a few methods for testing!

If you read an Exercise Science book, you’ll often read that underwater weighing used to be the gold standard. Now, you’ll probably read DEXA is the best. There’s also bio-electrical impedance analysis (BIA), BodPod, ultrasound and calipers… to name a few of the most popular choices. So, what’s the best?

In reality, there’s pros and cons to every test. If you’re running a large study, DEXA might be best. If you’re testing a group of deep sea divers or swimmers, underwater weighing might work. If you have a skilled technician, ultrasound or calipers might be your best choice.

To learn more about different body fat testing methods, listen to this Team LoCoFit Roundtable episode with Dr. Bill Campbell, Exercise Science professor and director of the Performance and Physique Enhancement Laboratory at USF. 

My personal favorite, as you’ll hear in the podcast, is using ultrasound and calipers. This does require a skilled technician but when done right, in my opinion, is the best test to actually see true changes. But as always, what you’ll be able to repeat and get reliable results is most important.

Now, let’s discuss how to get the most predictable results.

In order to get the most predictable results you need to do the most predictable things beforehand. Shocking, I know… but this actually is something that is overlooked quite a bit. In order to replicate your test you ideally need to go at the same time, work with the same technician and use the same testing protocol.

No, you can’t get your body fat accurately tested at 4PM.

Most people will be doing multiple body fat tests over some period of time, so the only way to accurately compare results is to make your experience as replicable as possible. This is why everything down to the same fasting protocol (from food AND water, hence why a 4 PM reading isn’t accurate) is key and if you are using a method of testing where a technician is highly involved, like calipers, it’s important to use the same person. Sure, you don’t need the same technician to run your DEXA but even reading and communicating results makes consistency important.

Lastly, what does all this mean for you?

You go for a body fat test. Yay, now you know your body fat! What now? Do you change your diet, increase your calories or cry in the car? Seriously understanding what to do with these results is the most important piece of the puzzle here.

First, understand that percentages vary so much from test to test. Your body fat on the same day could be multiple points higher or lower just based on the type of test you use. Calipers said 16%, BodPod might say 23%… with back to back readings. This seriously shocks most people but that’s why it’s so important that if you are going to get testing, you have to be very detached from those numbers and simply see a number.

Quite like the scale, seeing a certain percentage can be a trigger for certain clients. But why? Why is 16% good yet 23% is bad, but you have the same body? I understand why, and I’m not trying to downplay the mental strain tests like this can take on someone but it’s important to be as rational as possible with these tests.

Second, understanding that based on your goals, certain tests might be better than others. This is why I always go back to ultrasound and calipers. Sure, most people won’t have access to an ultrasound machine, but a quality pair of calibrated calipers is around $300 USD and can give you a much better insight into actual fat thickness changes. That’s what both these methods do best and actually give, again in my opinion, the best insight into body fat differences for someone who is interested in physique changes.

Lastly, like I mentioned above, getting hung up on the numbers is the last thing that you should be worried about with body fat testing. Why? Because of the many factors that are discussed above. Seriously, what difference does is make that you were 16% or 23% on one test but then over time during a calorie deficit you dropped to 14% or 21%? It shouldn’t matter but for many clients who struggle with comparison (towards themselves or against others) it can cause a cascade of compensatory behaviors and negative self-talk.

Over the past 5 years I’ve gotten many body fat tests done by Dr. Campbell, especially to track my contest preps. We’re both data nerds so enjoyed doing the tests and seeing the trends. I had tons of people ask me how I didn’t get upset over the numbers and how it didn’t negatively affect me during my prep. My answer mirrors what I wrote above: I use body fat testing as a tool, nothing more. I expect the number to change (and fluctuate), but understand the trends I should see. Since I also had a large data set, I could compare to previous preps too which was fun and not negative in any way. This is not the case for everyone, so if you find yourself struggling to see a certain number, it’s likely best to avoid testing all together.

Body fat testing can be incredibly insightful, empowering and fun to track. It can also create a negative mindset, obsession around a number and compensatory behaviors, based on said numbers. Understanding the entire picture before you decide to get your body fat tested (once, or multiple times) is incredibly important. Neither is right or wrong, but being informed is key.

Listen to our podcast for even more nuance and details into this topic!

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