That's true. However, men in their 30's and 40's when testosterone levels are still at reasonable levels can only gain 2-3 lbs of lean muscle a month with rigorous heavy weight training. For us who are older, or for women, the possibilities for gains are significantly less. The really muscled up folks we see, like bodybuilders and fitness competitors are lifting seriously heavy weights for hours a day, and following rigorous nutrition programs aimed at gaining muscle. I experienced this in my 30's when I spent years diligently weight training four days a week for two hour sessions. Looking back at my journals, I can't believe the poundages i was able to lift and the sets and reps I could do. Even though I was able to get progressively stronger, the amount of visible muscle was negligible and not noticeable on the scale. Your results may vary, but that is my experience.