When we measure body fat we usually measure a percentage of fat of the total bodyweight but to me this doesn't seem right and here's why.
Say my total bodyweight is 80kg and I measure my body fat percentage to be 10%, that is I have 8kg of fat. Now suppose I gain 5 kg of muscle only, now my total bodyweight is 85kg and my fat hasn't changed so 8kg of 85 is still fat.
This means that my body fat percentage now is 8/85*100%=9.4%.
So my body fat percentage has dropped but I did not lose fat, I believe this can be misleading.
If I am correct, why do we actually prefer measuring body fat percentage and not body fat in kg?