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L-Leucine is not a new supplement but some current research has shed some more light on this powerful essential amino acid.
It is an essential amino acid which the body can’t synthesise and is one of three branched chain amino acids (BCAAs). The others are valine and isoleucine.
These BCAAs make up a high number of amino acids within the skeletal muscle, and they are the only proteins that the muscle can use as fuel. Therefore, both muscle and blood levels of BCAAs drop post exercise.
In the past, many researchers believed that leucine’s only properties were to build muscle but now the scope of this powerful catalyst goes well beyond that remit!
It is well documented that by increasing protein intake in your diet will induce an increase in protein synthesis; this is the main rationale why protein shakes are the biggest seller within the sport’s nutrition market.
Current research is now honing on refining its knowledge and understanding of how protein actually stimulates muscle growth. Specifically, scientists have identified that it is the amount of amino acids within the blood that create protein synthesis within the skeletal muscle.
In fact L-Leucine has been singled out as the main catalyst for protein synthesis within your diet for building muscle.
The best piece of research to back up the claim that leucine is the driving force behind protein synthesis via dietary intake is broken down briefly as follows:
- When a complete protein diet was ingested protein synthesis increased in the muscle
- When the essential amino acids were consumed without the non-essential amino acids, protein synthesis increased in the muscle. This indicated that non-essential amino acids are not used to build muscle
- When only BCAAs were consumed protein synthesis was at the same magnitude
Here comes the kicker when only Leucine was eaten, protein synthesis was at the same level as the BCAAs intake.
Leucine stimulates the mTOR in the muscle
Leucine helps to regulate protein synthesis by activating the mTOR pathway. This pathway is very sensitive to levels of leucine.
A reduction in leucine levels signals to the mTOR that there is not enough protein in the body to create new muscle tissue. The mTOR pathway is then deactivated.
Conversely, high or adequate levels of leucine causes the activation of the mTOR pathway; resulting in the creation of the new muscle tissue.
A key point to remember is that when an overabundance of amino acids are available to build new muscle tissue, by adding leucine will increase protein synthesis even further.
Therefore, leucine has a vital role in up-regulating protein synthesis and this is an excellent supplementation strategy to maximise muscle building, especially when combined with the right resistance training program.
Leucine helps you to lose weight while retaining muscle
Diets which are high in leucine help to spare muscle loss and increase weight loss.
Research has identified that 10 grams of leucine per day combined with a high protein diet produced greater weight loss, greater fat loss and a higher preservation of lean body mass when compared to high protein diets without leucine.
In addition, the Leucine group exhibited better glucose control and a reduction in LDL cholesterols (the bad cholesterols).
How much L-Leucine do I need to build muscle?
The ideal amount of leucine required to supplement building muscle and/or weight loss is a matter of debate. When investigating single doses of leucine, as little as 1-2 grams was enough to stimulate protein synthesis.
However, some long term research has indicated that 8-10 grams of leucine should be consumed daily and at least 2-3 grams should be ingested with every meal.
Many of the whey protein powders have about 10 grams of leucine per 100 grams. Therefore, if you drink a whey protein shake of about 25 grams of protein, leucine content will be about 2.5 grams.
This is well in the daily range of 2-3 grams per meal and if your whey protein shakes powder does contain less than this amount, then maybe you need to think about switching it for a higher quality brand.
A key point to consider is that casein and soy proteins contain less leucine than whey protein products.
You may want to consider another option; such as buying a single amino acid or combined BCAAs formula to boost muscle gain/weight loss.
Many of the BCAAs contain between 35-55% leucine and a 5-7 gram dose contains about 2-3 grams of leucine.
Some of the BCAAs formulas tend to be less calorific than the whey protein powders.
In addition, you are consuming fewer calories but getting the same amount of leucine or BCAAs per sae. Another key point to consider is that if your diet is low in protein, then you should be supplementing with all 3 of the BCAAs.
Supplementing solely with leucine in this scenario will cause an oxidation imbalance, as leucine will be the only BCAA being utilised, causing a reduction in protein synthesis.