From my basic understanding and excluding the 100 variables
- When muscle mass is built there is a corresponding fat mass gain.
- when fat mass is lost there is a corresponding muscle mass loss
Diet, training and PED’s will impact the ratios these correspondences occur at.
I.e.
- A “Dirty Bulk lifting hard” without gear may produce a high ratio of fat to lean mass gain can increase overall body fat %.
- A well structured diet with a sensible calorie surplus (~500), solid training plan and correct anabolics program can reduce the fat to lean mass gain ratio.
If the ratio of fat gain to muscle gain is less than 1:1 then you can gain muscle while reducing overall bodyfat %. Also muscle and fat distribution can impact what a xx% body fat actually looks like. Ie someone with a 18% body fat on gear may a have well developed upper body which helps him carry the fat and look in better shape than a natty 18% er with a pencil neck and pigeon chest.
I remember some cyclists such as Floyd Landis got popped for Test. He was skinny af but the test probably reduced the ratio of muscle mass loss to fat loss and reduced “wasting” during the rigours of the Tour. This wasting prevention is something which most AAS were intially developed for.
I have no idea what these ratio ranges are mind you but i would be interested if some if the experienced bodybuilders / trainers know.