Supplements are substances taken by athletes or individuals involved in weight training or other physical activity to aid in the building of lean muscle mass or to cause fat loss. BSupplements may also be used to improve sports performance and improve recovery from events and training. The theory behind this supplementation is that having a sufficient protein intake allows for efficient growth and repair of muscle tissue. Some common supplements used are: Protein powder, this is generally consumed immediately before and after exercising, or in place of a meal. There are different types of proteins:

Whey protein is the most commonly used type of protein. It is absorbed by the body very quickly and easily. It contains high levels of all the essential amino acids, branched-chain amino acids and has the highest content of the amino acid cysteine which is important for the biosynthesis of glutathione; which has extremely important immune boosting properties for the body.

Casein protein (or Milk protein) is the richest in glutamine, an amino acid that aids in recovery[citation needed], and has casomorphin which helps the body to absorb the amino acids over a long time.

Soy protein contains all essential amino acids, and is an alternative protein for vegetarians. Soybeans also contain isoflavones, a type of phytoestrogen, which have a weak estrogenic activity

Creatine is another popular supplement,it is an organic acid naturally occurring in the body that supplies energy to muscle cells for short bursts of energy (such as lifting weights) via creatine phosphate replenishment of ATP. A number of scientific studies have shown that creatine can increase strength, energy, muscle mass, and reduce recovery time. In addition, recent studies have also shown that creatine improves brain function[14] and reduces mental fatigue. Unlike steroids or other performance-enhancing drugs, creatine can be found naturally in many common foods such as herring, tuna, salmon, and beef, making it difficult to ban it from sporting competitions.It increases what is known as cell volumization by drawing water into muscle cells, making them larger. This intracellular retention should not be confused with the common myth that creatine causes bloating (or intercellular water retention). Creatine is sold in a variety of forms, including creatine monohydrate, and creatine ethyl ester, amongst others. Though all types of creatine are sold for the same purposes, there are subtle differences between them, such as price, and necessary dosage. Non-supplemental suppliers of creatine include various types of offal, red meat, and kidney meat.