If you're looking to build muscle, boost your performance, and make the most out of all your hard work in the gym, whey protein is the way to go. That's not just because whey protein powder tastes great, is widely available (even grocery stores carry the stuff now), and goes down relatively easy. It's because science backs whey protein. Research suggests that consuming whey protein powder in conjunction with a resistance training program can help you maintain lean body mass and increase your upper and lower-body strength. But walk through the aisles of any supplement store, and you'll see a wide variety of different protein types.