If you're looking to build muscle, put down that soy burger – and pick up a real burger. A new study found that ground beef is more effective at building muscle than soy protein. Researchers found that a single four-ounce beef patty achieve better muscle-building results than two soy-based patties. It's all about the amino acids in beef, which are used by muscles more efficiently than soy. And to top it all off, beef also gets the job done with fewer calories.