Building abs is about exercising them. If you want to see them, eating healthy is a must! If your body fat percentage isn't low enough you might never see them if exercise them but don't eat well.

I'm not sure on the muscle gain shakes. I haven't personally used them but I imagine they would help build muscle everywhere, including the abs. I say give them a try and see if they work for you!

I am really skinny, I don't have a lot of body fat. Ive been doing sit ups, bridges, and flutter kicks for my abs. Thanks for the advice. What do you think is healthy to eat??