#1 Reason You Should Measure Body Fat

As most of you know, my main business is fitness testing. One of the tests we perform is the hydrostatic body composition test (underwater weighing). This method is known as the "Gold Standard" as it is the most accurate way to measure body fat. People often ask me why they should get a body fat test done. Here is a response I gave to that question on the blog of a body transformation contest where we were testing the participants.


Mr. Harris, I have read all about this competition and wonder about the getting dunked (hydrostatic test). Why can't you just use the scale as a measurement of weight loss?

Great question! The simple answer is body composition. The scale can't tell you how much of your weight is fat mass and how much is lean mass. Body composition is a much better indicator of overall health than just scale weight. For example, two women are the same height and weight. After "dunking" them, we determine body composition for one to be 25% body fat and the other to be 35% body fat. While they both weigh the same, the one at 25% would be in the healthy category and the one at 35% would be in the poor category.

Here is a real life example. We just finished the first retest of the Healthquest participants. Everyone made a positive improvement, however the improvement was different for each participant.

Let's look at the numbers for two of them:

Participant #1: Scale Weight-lost 8 lbs (sounds great!) Fat Mass-lost 4.8 lbs (woo hoo!) Lean Mass-lost 3.2lbs (uh oh).

Participant #2: Scale Weight-gained 2 lbs (yikes!) Fat Mass-lost 1 lb (good) Lean Mass-gained 3 lbs (yeah!!)

According to the scale, one of them lost 8 pounds and the other one gained 2 pounds, however both dropped 1% from their starting body fat percentage. Both ladies made a positive improvement in body composition overall, yet what happened on the scale was totally different. Losing Fat Mass is important but retaining Lean Mass is very important as well. While the scale is a good tool to use as a relative measure of the changes that you are making, you need to “get dunked” to see what the number on the scale just can’t tell you.