Depending on how much weight you want to gain or muscle you want to attain, you should eat more protein. I'm not sure how much you eat per day but if you want to gain muscle, yeah, you should probably eat about 2,500 calories per day. Chicken, eggs, red meat (though I'd limit the intake of this, lol), as well as protein shakes are the easiest and most efficient ways to acquire the adequate amount of protein you'd need -- most people seem to always have chicken, eggs, and red meat in their freezer, not to mention protein isn't hard to get though it can be pricey at times, lol. I actually replace a meal, mainly breakfast, with a protein shake.