How is fat-free mass calculated?

Fat-free mass is calculated by taking the current body weight and subtracting the fat mass. This approach is based on the understanding that body weight consists of two main components: fat mass and fat-free mass, which includes everything in the body other than fat, such as muscle, bone, and organs. By subtracting the amount of body fat (fat mass) from the total body weight, you isolate the fat-free mass. This calculation is widely used in nutritional analysis and weight management to help assess an individual's body composition and monitor changes in lean body mass over time.

The other options reflect different calculations that do not accurately represent the fat-free mass. For instance, adding fat mass to current body weight would not yield a meaningful measurement of fat-free mass, as it would incorrectly suggest that the fat mass contributes to the lean body composition. Multiplying body weight by the percentage of body fat or dividing body weight by fat mass are also not relevant calculations for determining fat-free mass.