The fastest way to gain weight would be eating more. Plain and simple but a lot of people aren’t dedicated enough to do this. If you lift properly (heavier weight) and eat properly, you will gain weight. Now it varies on how many calories you burn and what your weight is like in general. Let’s say for example you have somebody who is 150 lbs and they want to get up to 170 by next season. You should be consuming 150-170 grams of protein per day. Now this can be very easy if you make an effort. And yes, it’s going to cost money to pay for food but what if a college coach told you to gain weight? You would do it right? Because that could mean a spot on their team and a possible discounted tuition or free because of a scholarship. That’s how you have to look at it. You could easily do a high protein breakfast, lunch and dinner with high carbs. I’ll give you an example: Breakfast: Eggs, potatoes/oatmeal and a banana. You could even put protein powder in the oatmeal if you choose. After your first class: protein shake that you pre packed. Lunch: Chicken Breast, Pasta/brown rice and a fruit or vegetable. Then you go to practice. After practice you have a protein shake. Then dinner: Some kind of chicken or beef, pasta/brown rice and a vegetable. That’s what dedication is. And maybe 1 more shake before you go to bed. Yeah that sounds like a lot of work but how bad do you want it?