Whey protein is one of two proteins found in milk; the other protein is called Casein. While protein is important for muscle building, it does not need to come from supplements. In fact, many supplements are expensive and some can be harmful to your body. There are many foods that contain protein including lean meats, such as chicken and turkey, eggs, milk, Greek yogurt, nuts, nut butters (like peanut butter), beans, and tofu. Eating protein with all meals and most snacks is important for a healthy body.
Wanting to be fit is a great goal that can be achieved by eating healthy and being physically active every day. Healthy eating includes eating regular meals (aim for 3) and healthy snacks when you are hungry. You should try to have foods from all food groups including fruits, vegetables, protein, carbohydrates, and dairy. Physical activity that includes weight training can help you build your muscle mass.
If you have more questions about nutrition it may be helpful to talk to talk to your health care provider or a registered dietitian.