Optimum Nutrition 100% Gold Standard Casein Protein is a Micellar Casein which is low in fat, sugar and carbohydrate.Each serving provides 24g of slow release protein providing your body with a continual supply of high quality Protein and Amino Acids. It contains Branched Chain Aminos and Amino Acids such as L-Glutamine, Leucine, Isoleucine and L-Valine. Amino acids are of importance due to their role in stimulating protein synthesis. Protein contributes to a growth in and maintenance of muscle mass. Therefore increasing protein intake may be of particular benefit to those working to build muscle mass.Slow digesting Protein and Amino Acids, such as found in Optimum Nutrition 100% Gold Standard Casein Protein, helps to satisfy your appetite. It can be enjoyed at any time but is of particular use before bedtime as a continual protein source to feed your muscles.