Did you know you can trick your body fat meter with water, making it think you have a different body fat percentage than you actually do? Now I doubt you would want to do this on purpose. What’s the point of measuring if you’re going to fudge the results. But knowing how you could trick your meter into giving incorrect results tells you how to make it give more accurate results. So let me explain how to trick your body fat meter and we’ll take it from there.

First off, you need to know that this trick only works for devices that use bioelectrical impedance analysis (BIA) to figure out your body weight. In other words, if you use one of those gizmos that applies a tiny electrical current to you to measure your body fat percentage, this trick will work.

The Trick

Here’s the trick. To make your body fat device show a lower body fat percentage, make sure you drink plenty of water to keep yourself well hydrated. Conversely, to make it show you to have a higher body fat percentage than you actually do, let yourself get dehydrated.

Here’s why the trick works. BIA devices measure the amount of resistance your body provides to the small current they zap you with. Fat has less water in it than muscle, and provides more resistance. And muscle provides less resistance than fat. In effect, the device is measuring the overall amount of water in your body. You can trick it by manipulating the amount of water in your body yourself.

Drink a lot of water and stay well hydrated, and your device will show you to have a lower body fat percentage. Don’t drink enough water, or get yourself hung over and dehydrated that way, and the device will show you to have a higher percentage.

How Knowing the Trick Helps You

If you know how to trick your body fat measuring device, you also know how to make it more accurate. Try to keep your consumption of water and other liquids consistent from day to day. Doing that will keep the amount of water in your body relatively consistent, which will make the results from the device more consistent. Along the same lines, be consistent about whether you have anything to drink right before you measure. A big glass of something shortly before you measure could throw off the results too.

And don’t measure your body fat percentage if you had a lot of alcohol the night before. You probably won’t like what you see. Alcohol dehydrates you and that will make your body fat percentage appear to increase.