Protein is the ingredient that is responsible not only for muscle building but also maintaining bones and organs. It is also responsible for making hemoglobin in the blood. So as you can see, without a proper supply of protein, all your hard work in the gym will not pay off. Furthermore, when it comes to reforming your physique more protein is required for more muscle and fitness. It is not possible to have just protein-enriched food every day so it is good to supplement your everyday meal with some quest protein bars.