Episode 46 - Protein and Muscle Growth/Retention

Key Topics Covered

Background

You can categorise important aspects of protein in 4 key areas:

1) Total Protein Intake

The most important factor when it comes to protein intake is total protein intake.
It is super important to be aware that this is the most important factor, since sometimes it nullifies other arbitrary rules like:
- “You can only absorb 30g of protein per sitting.”
The research shows that for relatively lean people wanting to optimise muscle growth, we want to be:
- Aiming for 1.6-2.2g/kg of Bodyweight per day
- Eg. An 85kg athlete would be aiming for 136-187g
But if they limited to “30g per meal MAXIMUM” over 4 meals, they would end up with a maximum of 120g?!
This is especially relevant for those who intermittitent fast or are time poor. It shows that if you’re trying to maintain or grow muscle, the more important factor is simply hitting your total required protein each day.

2) Distribution of Protein

Even though total protein intake matters most, distribution is still super important.
The reason “your body can only absorb 30g protein in one sitting” was broadcasted was due to a study that showed that muscle protein synthesis is only slightly increased after 30g of protein.
- But while higher dosages DO lead to significantly higher rates of amino acid oxidation e.g. not being used for muscle growth, there is still some that will be used for the creation of muscle tissue.
- More importantly we care about longitudinal data focused on muscle growth more than acute muscle protein synthesis studies.

A review of all the research on the topic (including both longitudinal and acute data) up until 2018 by Brad Schoenfeld and Alan Aragon concluded that the best approach would be to aim for that 1.6-2.2g/kg/ day AND achieve this by aiming of 0.4-0.55g/kg of protein per meal over a minimum of 4 meals
And interesting line from that paper was “Consumption of slower-acting protein sources, particularly when consumed in combination with other macronutrients, would delay absorption and thus conceivably enhance the utilization of the constituent amino acids.” – which is part of an explanation as to why the whole 30g being the limit thing might be less relevant than a lot of people think

Summary: If you want to optimise muscle growth, aiming for 4-6 meals with >20-40g of protein (depending on size) is the best approach. But 3 is almost as good as this too.

3) Protein Quality

Protein is made up of amino acids:

There are 20 amino acids, 9 of which are essential (we can’t create them).
3 of them are BCAAs – which are most strongly linked with muscle growth.
1 of those is leucine – which is the one that is the most linked with muscle growth.

3 main components of protein quality

1. Leucine threshold

Leucine “triggers” muscle protein synthesis
We want to aim for 2-3g of leucine per meal to optimise muscle mass growth.
Most animal sources will hit this easily. People on a plant based diet may struggle with this, soy is one of the proteins highest in leucine.

2. Protein quality – Overall amino acid profile

This refers to those foods that are “complete proteins”, where they have all of the essential amino acids.
- e.g. If a protein source is missing or low in a key amino acid, under some circumstances it might be sub-optimal for muscle growth.
Most animal protein have a ‘complete’ amino acid profile except for gelatin/collagen protein.
Most plant based source are considered incomplete, except for soy.
- To optimise muscle protein synthesis on a plant based diet, I often recommend protein combining within meals that are not soy based – outside of the context of optimising this isn’t necessary
But if you have a high enough total protein intake, coming from a variety of sources, often this stuff sorts itself out without much thought.

3. Protein quality – Digestibility

The amount of protein digested and absorbed differs between protein sources
Animal source usually have really good digestibility
Whilst again plant based source have a lower digestibility.
- This is because plant based proteins are often higher in fibre, which makes it harder for the gut to absorb.
This just means if you are relying on plant based source, you probably need 10-20% more total protein intake to optimise muscle protein synthesis OR aim for the higher end of that 1.6-2.2 range.

4) Specific Timing

What we’re talking about here is that specific timing of taking protein. Ie. Having a quick digesting protein post workout like whey protein, or having a slow digesting protein like casein before bed.

In terms of post-workout protein, this is what is referred to as the anabolic window. Some people consider this to be a 30-60 minute window where it is super important to get >25g of protein in. Others consider it to not matter at all.
The answer is somewhere in the middle.

Another review by Alan Aragon and Brad Schoenfeld titled “Nutrient Timing Revisited” concluded that it is still beneficial to have protein 3-5 hours around the time of your workout.
- The 5 hour aspect is only really relevant if you have a large amount of protein a few hours before training e.g. >40g at minimum. This is theoretically because of the delayed digestion/absorption aspect.
- Therefore the 3 hour around your workout is more relevant. And if you happened to train fasted, that would give you roughly 1.5hrs to get protein in, if you want to optimise things. So the anabolic window is far more important if training fasted.
Outside of that, if you have 4+ meals/snacks that are high in protein, this is likely to work itself out without you even thinking about it. But having protein post-workout is not really a bad idea, since it basically means it will be a habit that guarantees you meet this criteria every time.

The whey vs casein argument makes sense logically, but studies measuring muscle growth have found no difference when comparing whey vs casein post workout. So clearly it is not a massive priority. Part of this is because muscle protein synthesis is elevated for 48-72 hours post workout.
If training in a fasted state, outcomes might be different though e.g. whey might be more relevant.
The casein before bed hypothesis also makes sense logically, but when protein intake is optimised through having enough total protein intake, from a variety of sources, spread out over 4-6 meals/snacks with 30+g of protein, it no longer appears to show benefits.
We don’t literally need to consume protein around the clock – it seems like that process can be optimised with a 10-12 hour eating window.

Useful Links/ Resources

Studies Mentioned