If you want to gain muscle mass, here are the simplified basics of putting on size
1. Eat big to get big
Gaining muscle and getting the muscular body that you want is calorie driven. To gain muscle mass, you have to eat more… period Sure, you could throw down a few burgers each day and gain mass, but it won't be the kind of muscle weight you want. So Eat good foods instead, make your diet high and low in fat. So, to gain muscle mass, eat big.
2. To get big, lift big
None of this isolation stuff people do… those lifts need to be saved for once you have most of the muscle that you want. To gain muscle mass, you need to lift heavier and heavier weight over time. For the most part keep the reps low so you can get up more weight. Stick with tried-and-true basics like squats, deadlifts, bench, barbell rows, bar bell curls, and military presses. Skip the high reps, use them in your training no more then one out of every 8 weeks of training.
3. Get Enough Rest
After the other 2 steps, rest and recovery is the next most important. Without proper recovery, your body doesn't heal from the previous workout and no new muscle growth can take place. Weight lifting tears down muscle. Rest builds it up.
4. Drink lots and lots of water, it helps to purify your body and keeps your muscles full.
There you have my 4 steps to gain muscle mass.
Do they work---yes
do most people do them---No
which is why most people lack results!