Many people who want to reduce their weight may think why should we know about the body fat? And why should we calculate the body fat? The reason for measuring the body fat is that it is the realistic measurement of fitness of our body. Fat loss is nothing but weight loss. Body mass index is an indicator of the health and fitness of the body. The big disadvantage of the body mass index is that it may conclude that you are overweight. But your body fat may be normal. When the body fat is normal, your health is perfect though you are overweight. Hence body fat calculation is the best method to assess your fitness.