The main component of muscle fibres (myfibrils) is protein. Proteins are made up of 20 different (so-called proetinogenic) amino acids.
The two types of protein found in milk are whey and casein. Casein is a more slowly digestible protein. It contains all 9 essential amino acids (essential for life). Its slower absorption makes it very filling, a good choice for people who want to reduce their appetite. Consumed before bedtime, it will keep your body supplied with amino acids throughout the night. Sleep is a critical time as it is when large amounts of growth hormone are released, which stimulates the building of protein into muscle.
During exercise, the proteins that make up muscle are damaged (micro-tears). To heal this, an inflammatory process occurs, during which the inflammatory cells digest (catabolize) the damaged muscle fibres and new protein is produced (synthesized) to replace them. - This explains muscle fever.
The processes of protein synthesis (building) and protein catabolism (breaking down) occur in parallel in our body.
The main requirement for muscle building is that protein synthesis is positive, i.e. more new protein is built than is broken down - a growing number of studies are finding that even a calorie surplus is not necessarily required to build muscle, do with the right diet and training protocol, you can increase muscle and reduce fat mass at the same time.
With adequate protein intake, stimulating muscle growth can help preserve muscle during weight loss. Adequate protein intake is essential for all people.