I am a 16 year old that plays high school baseball and is a starting pitcher. I am 5'9" and weight about 150 lbs. I want to have a body that looks real good. Some people tell me that to do that I should gain lbs. so i can get a little fatter and then work it out and other people tell me to lose lbs so my abs and all that will show more. Which one or what should I do to accomplish this. Also, what should I eat to do this?

Don't get fat in hopes of getting bigger or making it easier to gain size. You will only get fat. Then, you will have to work extra hard to get lean so your abs will show. The best thing to do is to eat healthy, take quality supplements like AST Micronized Creatine and Glutamine and Myoplex or Met-RX shakes and you will have everything you need to put on muscle size as quickly as possible. You need to eat quality protein sources like tuna, chicken, turkey, fish, egg whites, and cottage cheese. Then you need to eat quality carbohydrates like vegetables and fruits (apples, broccoli, oranges, tomatoes, green beans, lettuce), whole wheat grains and oatmeal. Also, nuts, seeds and peanut butter are a great way to bring some healthy calories into your diet so you can put on some size and increase your power.