Alan Arogon's Natural Lean Muscle Mass Gain Model
According to Aragon, advanced trainees near their genetic potential are lucky to gain 0.25% to 0.5% of their total body weight gain as fat-free muscle per month. That makes the 10-pound-gain claims of already ripped celebrities seem outrageous, right?
In my opinion, it's rare to see a natural bodybuilder or fitness enthusiast close to their genetic muscular potential gain more than 2-3 pounds of lean muscle in a year. This is why it's an accomplishment when experienced bodybuilders manage to gain 7-10 pounds of fat-free muscle in a year.
https://www.bodybuilding.com/content/ask-the-ripped-dude-how-much-muscle-can-i-put-on-naturally.html