When we designed the 52 Weeks to Peak Physique challenge, we decided it was important to establish some parameters and ways to measure our progress from the very start so that we would be able to track our progress and ensure that we didn't get too carried away. In addition to weight and measurements, we decided we should also try to measure body fat percentages, but what we have come to discover has had me questioning - is body fat an accurate and reliable measurement?
There are a lot of ways to measure body fat percentage, but many of them, such as DXA X-ray scans, or hydrostatic weighing where you submerge into a tank of water, while fairly accurate, just aren't practical for regular use. We have tried a few different methods to measure our body fat, including two different BIA (Bioelectrical Impedance Analysis) devices (a handheld device and a bathroom scale), as well as a calculation that uses your weight and BMI
to calculate your body fat percentage. The result? Numbers that are all over the map!
When I stepped on the scale, my result was 19.4% but when I ran my calculation, my result was over 25%. That is 6 percentage points of variance! I didn't have access to the handheld device, but JC did, and between all three methods, his numbers spanned over 10 percentage points depending on which method he used. I should also note, that the different methods fluctuated in different directions for both of us, so they weren't even increasing or decreasing at a consistent rate. The problem is that these devices aren't really measuring your whole body, and they can't always tell the difference between muscle and fat. For example, when you stand on the scale, a small electrical current will run up one leg and down the other in order to measure your body fat. The problem here is that you are only measuring your legs (similar issue with the handheld device), not your whole body. Add to this, if you're muscular and athletic, it can skew your reading based on the mass. These devices can also be skewed by hydration and glycogen levels, and variance in the placement of your hands or feet on the device. The written calculation doesn't do a great job either as it only takes into account your height and weight, which doesn't accurately represent your muscle to fat ratio.
We've considered calipers, and other methods as well, but based on the results we've had so far, I'm not sure that any method will provide a more accurate measurement. Ultimately, we decided that the actual number doesn't matter as much, but as long as we use the same device every week, we should still be able to measure our progress, which is really what we need it for. My point here is to say, don't let the body fat number on the scale scare you! The main goal is to continue making progress toward your goals, and remember to take these numbers with a grain of salt, because they might not be as accurate as we think.