Protein is a vitally important part of an athlete's nutrition plan. It contributes 10 to 15 percent of your energy while exercising in addition to being the building block of muscle growth and regeneration. While both endurance and strength athletes have an elevated protein requirement, most people can obtain all they need from normal food.
Eggs (specifically the whites) are a fantastic source of protein for athletes, as they contain all nine of the essential amino acids (the protein building blocks that aren't supplied by your body). One large egg white contains roughly 17 calories and four grams of protein. So you're going to need a lot more than three egg whites to get that protein requirement. The protein shake can help, but you're missing out on a lot of other important nutrients you get with protein from natural food sources.
Consider meat sources like chicken breasts and lean cuts of red meat, or fish like salmon and tuna that also contain heart-healthy omega-3 and omega-6 fatty acids. These options contain seven grams of protein per ounce. Cheese and low-fat dairy products are also good sources of protein, as are nuts and even whole grains. Soy is another great option because it is the only vegetable source of complete protein.