The purpose of whey protein is to provide protein supplementation for people who either don’t get enough protein in their diet through normal eating or want to ingest a lot of it fast. It is true that after you exercise you should consume both proteins and carbohydrates to repair and rebuild your body. Often people use whey protein for this. But if you are working on losing weight there is no reason you need to be drinking your protein or supplementing. You would be much better off having a small healthy snack after your workout than having a protein shake. Some nuts, some lean turkey, or beans. These would all be much better options for you . Basically you don’t need it for what you want to do and it’s not going to be of any help in your case.