[724Skinsfan]

Focusing on the large muscle groups will help increase your muscle mass. The larger the muscle, the more weight you will gain. I went from 120lbs to 170 lbs in 4 years without paying any attention to diet or taking a single supplement or drinking some protein shake. Just simple weight training with the purpose of developing the muscles, special emphasis on the shoulders, upper chest, triceps and lats. 8 years later with minimal weight lifting, I still weigh 170 lbs at age 32.