Protein is the building block of life. You need a healthy dose of the macronutrient daily to build muscle. Plus, protein gives you energy. A new study from the University of Illinois found the humble egg to be a great source of high-quality protein. Egg protein helps preserve muscle mass and provides steady and sustained energy. The study recommends eggs as a protein source for endurance athletes since eggs are high in the amino acid leucine, which helps muscles utilize the fuel glucose. If you were avoiding eggs for health reasons, it is considered safe to eat six eggs a week.