My goal, whenever entering a project, is always to gain 12 pounds.
In a key--but commonly overlooked--aspect of obesity, weight gain can be caused by the slightest increases in consumption, if it continues day in and day out.
At one point I had to shove as much food in my body as possible to pack on calories. My trainer wanted me to do six meals a day and not go two hours without eating. If I would cheat on eating one day, I could tell - I'd drop a few pounds.
When your goal is to put on muscle mass you must increase your calorie intake as you increase the activity level being given to the muscle.
You can dramatically affect the expression of your metabolism and your biochemistry by the way you eat and the way you live.
Guys like me can put on 10-15 pounds in a week.
I've often said that while gaining muscle can be very difficult, it's also pretty simple - at the heart of it, you just need to take in more energy than you expend, and use an intelligent program. This is especially true for beginners.
The path to added muscle is consuming more calories than the amount needed to keep your current bodyweight unchanged.