Body Fat Percentage is a measure of the percentage of a person's body weight that is body fat. All measurements of body fat percentage are estimates as fat is contained throughout the body and cannot easily be measured independtly of total weight. Players participating in the GripIron Fitness Challenge typically measure body fat percentage using a body fat scale. These scales work by emitting a tiny electric signal through the body measuring the amount of resistance (electrical impedence) they receive. This resistance can be used to estimate the amount of body fat a person has.

For best results, body fat should be measured first thing in the morning before eating or working out. Fluctuations from day to day are normal, but when a person is losing body fat this trend will appear over time.

The American Council on Exercise has defined the following body fat percentage classifications.