you have to eat a TON when trying to gain mass. creatine and whey and all that are decent for giving protein, but they won't do anything unless you are on the right program. What is your routine? how often do you work each muscle? i would suggest 3 - 5 exercies for each muscle. And, for someone that's trying to put ON weight, you can't be on a low or no carb diet. the whey/creatine are good, but you have to have some carbs to go with them. here's my current routine to give an idea...
friday and saturday-off
i do 30 min. cardio each work out day. remember also to eat protein (tuna, chicken breast, turkey, salmon, etc.) even on your off days.
to add mass, you don't want to to 16 reps. you want to do more weight less times. so, if you can do 16 reps of bench press, you want to be doing 180lbs. 8-10 times instead.
good luck... pm me and I can give you a few good weightlifting sites.cheers,
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