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Wednesday, 2nd December 2015 | By Bobby Garlington

Supplementation with Leucine has become increasingly popular. Leucine is one of the 3 branched chain amino acids which need to be consumed as the body is unable to produce them. It has been found to have many potential benefits such as aiding muscle growth, fat loss and glycogen replenishment.

Muscle Growth/Hypertrophy

Leucine is most well known for its role in both maintaining muscle mass and stimulating muscle growth. It has a far greater effect on the synthesis of muscle protein than any other amino acid. It helps convert the body from a catabolic state where muscle tissue is broken down into an anabolic state where muscle is being formed. It does so by activating the m-TOR pathway which is responsible for stimulating muscle protein synthesis. This property of Leucine means that it is beneficial to athletes who are looking to increase muscle mass such as bodybuilders and rugby players as well as those looking to maintain the muscle mass they have, such as endurance athletes.

Fat Loss

Leucine has also been suggested to assist with fat loss. This is due to its ability to help prevent the breakdown/loss of muscle tissue which slows down a person’s metabolism. A slower metabolism is not only going to prevent fat loss but will increase the likelihood of fat being put back on once lost. Whilst it is possible to lose weight without a sufficient leucine and protein intake it is likely that a large proportion of weight lost will be lean muscle mass rather than fat.

Glycogen Replenishment

Consuming leucine after a workout has been found to influence glycogen replenishment following exercise. A study by Detko et al, (2013) found that the addition of leucine and whey protein to a carbohydrate drink reduced the amount of carbohydrate required to replenish glycogen stores. This is likely due to this formula causing a larger amount of insulin to be secreted. The study mentioned used the unique formulation found in GlycoSource.

Sources of Leucine…

Leucine is present in a variety of foods with the best sources being animal products such as beef, chicken, eggs and fish. Leucine can also be consumed through supplementation with whey protein, which has a higher leucine content than any other protein source. Alternatively, leucine can also be consumed as a BCAA formula or as a single amino acid.


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Reference List

  • Detko, E., O'Hara, J. P., Thelwall, P. E., Smith, F. E., Jakovljevic, D. G., King, R. F., & Trenell, M. I. (2013). Liver and muscle glycogen repletion using 13 C magnetic resonance spectroscopy following ingestion of maltodextrin, galactose, protein and amino acids.British Journal of Nutrition110(05), 848-855.


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