When it comes to understanding how much muscle mass you can gain in a week as a male, it’s important to set realistic expectations. On average, a beginner male following a proper strength-training routine and consuming a protein-rich diet can gain around 0.25 to 0.5 pounds of lean muscle per week under ideal conditions. This rate may be slightly higher in the initial stages of training due to “newbie gains,” where the body responds quickly to resistance training.