"Fat percentage" refers to the proportion of fat in your body compared to the rest of your weight. It indicates how much of your body is made up of fat. Full definition
To get your body fat percentage low enough while remaining in a healthy range, the ratio of protein to carbs to fat you consume matters. (homefitnessguru.net)
To sustain his growth and large bones, you want a higher fat percentage as well, around 20 %. (dogcare.dailypuppy.com)
This is because women generally need a body fat percentage of at least 20 percent in order to remain fertile and have regular menstrual cycles. (mindbodygreen.com)