Hello friends, firstly if u r really passionated towards gym then ur art right place. if it lean, start doing regular exercise at home and then go for gym training.normally, for a body builder, protien plays a crucial role in muscle building. On gym training, muscle tissues get damaged and it should be repaid by protien which is made up of aminoacids. First 3 months start ur diet with normal food, till then don’t take Protien supplements. Because, normal person can digest 25gms of protien at a time, but a body builder can digest protien more than that easily, so even if u take supplements at starting stage, it is waste as ur body can’t digest.always keep in mind that, " food -exercise-rest" should be in cyclic order, if any one is missed, u can’t gain muscle, it is the biggest secret.also don’t repeat the same body part exercises regularly, change the exercises daily, as ur body needs rest to build muscle. all the best thank u!