Leucine - the master key to muscle growth

Here's what we've all been told our whole life: In order to get big and strong, you need to feed your muscles enough protein to grow. After a session of heavy lifting, most of us almost sprint home to eat our protein-rich post-workout meal or our post-workout protein shake. Though it is true that we need enough protein to grow, the whole truth is just a bit more complex. We need to look at what kind of protein we are actually getting in. More specifically, we need to look at what these proteins are made of. 

Proteins are built from amino acids. These amino acids are often relatively small molecules and chain together to create a protein. There are 20 different amino acids humans use, out of which 8 are essential and must be obtained from the food we consume. In other words, we need to eat specific types of proteins which contain these amino acids in order to properly function and of course to build or maintain muscle mass. In this image, you can see which amino acids humans produce and which amino acids are essential amino acids. 

The one amino acid that deserves a lot of attention is Leucine. Leucine is one of the 8 essential amino acids we must obtain from our diet and is also called a Branched Chain Amino Acid (BCAA). Other BCAA include Isoleucine and Valine. You've probably heard of that term before haven't you? BCAA's are very popular among gym-goers because of its supposedly muscle protecting properties during a workout. What most people don't know however, is that not only is leucine the most important of the three BCAA's, but leucine does so much more than just protect your muscles. Leucine is actually the master key to muscle growth. You read that right! Leucine is the single most important component from your protein intake that determines wether you will build muscle or not. Leucine is basically the switch that turns muscle growth on and off. Without proper leucine intake, we won't see as much muscle growth. 

 Source:  www.physoc.org

So not only is leucine intake important for muscle growth, we also need proper amounts of leucine to make those muscles grow. Science calls this the 'Leucine Threshold'.  As you can see on the image, we need sufficient amounts of leucine to surpass the threshold given with the horizontal dotted line. This threshold is 3.2 grams of leucine per meal consumed. That means, every time you consume 3.2 grams of leucine or more, your body immediately activates a cascade of hormones and signalling molecules which activate muscle growth. The important thing to realise as well here is that your body also needs enough total protein to effectively build muscle. According to research, any amount of protein between 1.6 - 2.4 g/kg bodyweight will be enough. 

So now that you know the science behind leucine and how much you need to consume per meal, how do you effectively get this amount of leucine in? The most logical answer is to eat foods that are rich in leucine. Foods that are rich in leucine include beans, legumes, corn, grains, tofu, tempeh, soy based products and also animal protein. Animal protein usually has the highest amount of leucine you can find, but shouldn't be the reason to turn to animal protein. Eating enough amounts of proper plant-based protein sources will do the job equally well.  

 L-Leucine supplements typically sold as a shake (or tabs). 

L-Leucine supplements typically sold as a shake (or tabs). 

The other option is to supplement on leucine. Most people have used BCAA supplementation before, but are you getting enough out of your BCAA supplements? The answer is usually no. Most BCAA supplements have a 2:1:1 ratio, which means that the leucine content is twice as high as the isoleucine or the valine content. That shouldn't be a problem though, if you take the right amount of your BCAA supplement in. The recommended dose is usually 5 grams, which usually means you get 2 grams of leucine. And that's not enough to surpass the threshold. The solution is to either double the recommended dose (10 grams of BCAA, giving 4 grams of leucine) or buy a pure leucine supplement and serve yourself about 3.5 grams (depending on the leucine content per gram). They are usually not very expensive and last you at least a month. This is actually an amazing investment for vegans and vegetarian, as most people have difficulties reaching the leucine threshold needed. 

Whilst BCAA's and Leucine is very popular among bodybuilders and more experienced gym-goers, it's important that everyone who is looking to add on some muscle mass or shape their body surpass this threshold at every meal. Even the ladies who don't want to put on too much mass need to ingest enough leucine. Without it, you are very likely to progress at a much slower rate or not at all. 

 Ladies, to look fit and sexy you too need leucine!

Ladies, to look fit and sexy you too need leucine!

So my recommendation is: take a look at the amount of leucine you are ingesting from your food and if this is not sufficient, change the amounts you are eating and/or add a leucine/BCAA supplement to your diet in a proper dosage. 

Let me know what your experience is with BCAA/leucine in the comments below. Share this with anyone who needs to know this valuable piece of information! 

Claudio Fray

Fray Fit, Rosseelsstraat, Den Haag, ZH,