Want to build massive muscles quicker? According to a Texas study, casein may be an important ingredient to your success. Researchers took 36 males performing heavy resistance training and found that the group consuming a whey and casein combination significantly outperformed participants who were given a combination of whey, BCAAs, and glutamine supplement. Over the course of the 10-week study, the whey and casein combo yielded the greatest increases in lean, fat-free mass. Why take only one form of protein when a combination yields much better results?