In the previous muscle building series we examined the impact resistance training volume has on muscle growth or hypertrophy. Continuing on from this I now want to take a deep dive into the role nutrition plays within the muscle building process and provide you with useful and digestible insight within a single article.
Over recent years we’ve been bombarded by everyone from work colleagues to supplement companies on the importance of protein intake within a healthy diet. The emphasis is turned up even more dials when muscle growth gets thrown into the conversation, but why is this and is protein intake as important for muscle growth as we’re told? And is there a ceiling to protein consumption and the amount of muscle we can build? All this and more is discussed.
What Is Protein?
It seems like a fairly bland and general question but with protein playing such an important in the muscle recovery process, having a decent understanding of what is actually is and it’s role is necessary, so hang in there!
All the food we consume can be broken down into 3 sub-categories called macronutrients or ‘macros’, these are fats, carbohydrates and proteins. They all have fairly distinctive roles within the body: carbohydrates and fat are the body’s primary energy reserves, with fat also being key in other crucial processes, such as healthy cell formation and consequently, hormone synthesis.
Although we can derive energy from protein, it isn’t preferable and is quite an energy rich metabolic process. Protein will only be used for this purpose if the diet is lacking carbohydrates and fats or an excess of protein beyond it’s utilisation is consumed. So if we’re not able to extract energy from protein effectively, what is their purpose in the diet?
Instead of offering a readily available source of energy, proteins are instead necessary for the replenishment and development of structural components of the body, such as your skin, hair, nails and also your muscles. The composition of muscle tissue is 75% water, 20% protein and 5% salts, glycogen and fat.
Essential And Non-Essential Amino Acids
When we consume the previously mentioned macronutrients each then begins to be digested by the body. Carbohydrates and reduced to glucose (blood sugar); fats become fatty acids and proteins become amino acids.
There are 20 different types of amino acids, which can be further sub-divided to essential and non-essential amino acids.
We don’t need to consume non-essential amino acids as our body is able to produce them, however there is no such luck with essential amino acids (EAA): it is essential for us to consume these within our diet. When it comes to building muscle, the terms protein and essential amino acids in research terms are one in the same, and it is essential amino acids that really drive muscle *anabolism, when paired with resistance training. This is largely due to the impact of BCAAs (leucine, isoleucine and valine) and specifically leucine’s impact on the mammalian target of rapamycin (mTOR), which up-regulates protein synthesis).
Essential amino acids are abundant in many animal based foods, include meat, eggs and dairy. For this reason – aswell as convenience – whey protein is often used as a proxy for EAA in studies which we will come onto.
Vegan diets can also be EAA rich, however plant based protein sources need to be varied, as some plant based foods have high amounts of some EAA and none others.
*a state of muscle growth and the opposite of muscle catabolism: a state of muscle breakdown.
Net Protein Balance
Like many states within the body, net protein balance (NPB) is transient and often pulling and pushing into a state of muscle protein synthesis (MPS) or muscle protein breakdown (MPB). When it comes to increasing muscle mass we need to ensure our diet is geared towards favouring a state of muscle protein synthesis as this is what allows for recovery, training adaptation and ultimately muscle growth.
Fasting for sustained periods of time may have benefits outside of the context of muscle growth, however will increase the risk of MPB allowing for more energy yield within the body.
Training can also lead to MPB within the confines of the training session itself however weight training can then lead to an increase in MPS post session to counter-balance this and combined with adequate nutrition places the body into a positive net protein balance allowing for muscle growth.
With this in mind it raises the question of cardio and it’s impact on muscle development. The aerobic nature of cardio typically means the session goes on for an extensive period time leading to a heighted calorie expenditure; increased risk of being in a long-term calorie deficit, increase in MPB and without the necessary mechanical tension allowing for hypertrophy. Overall a fairly catabolic state. For this reason I encourage people to limit their cardio if adding muscle is the primary objective.
Muscle Protein Synthesis
Now we know the equation for muscle growth how can we ensure we’re maximising MPS and getting the most out of our nutrition and maximising results?
As the term suggests MPS allows for the protein we ingest to be utilised so we can effectively recover from resistance training and also sustain muscle tissue, without said process we’d be vulnerable to a lot of muscle wastage very quickly! This is a common problem seen among the elderly population where MPS drops off, muscle tissue is lost which can lead to mobility issues.
The food that we eat spikes MPS in order to convert amino acids into muscle tissue, however this process only happens for around an hour and half after a protein rich meal/supplementation and isn’t increased in duration any longer despite amino acid availability (3), this is often referred to as the ‘muscle-full set-point’ (MFSP).
One way to increase the timespan MPS and push back the MFSP is using acute bouts of anaerobic focused training such as resistance or even true high intensity interval training, however if nutrition is inadequate this can still lead to an unfavourable NPB as you run the risk of significant MPB.
[If you haven’t already be sure to check out the article relating to training volume and hypertrophy.]
It’s therefore important to factor in the consumption of essential amino acid rich protein post training, which can help with sustaining a net protein balance which is conducive to gaining muscle and maximising the benefits of MPS.
Protein Amounts, Meal Frequency And Muscle Protein Synthesis
At this stage we’ve determined that the inclusion of protein within our diet is very much necessary, but how much is necessary in order for us to maxmise MPS and how should this be factored in within a 24 hour day with frequency of meal/EAA feedings?
Context is an important factor when determining how much protein an individual can utilise. For example guidelines for a 60 year old sedentary female will differ greatly compared with an active 20 year old male with bodybuilding ambitions and already a large amount of muscle tissue. For this reason studies will provide protein feedings based on the bodyweight (often kilograms) of the subject.
A review by Morton et al in 2015 on trained individuals delved deeply into the topic and found that 0.25grams-0.4grams/kg bodyweight/meal to be optimal for MPS, anything beyond this threshold did not yield a significant difference, with the amino acid absorption being utilised elsewhere such as energy oxidization or to form urea.
With the recent surge in popularity of intermittent fasting or similar weekly protocols, there is more of a trend to eat larger meals or higher caloric intake in shorter timeframes. With the One Meal A Day or OMAD diet being the more extreme end of this spectrum. However in terms of MPS and hypertrophy it is more effective to split these meals out throughout the course of a day.
Areta et al’s examined the topic of protein intake frequency in their 2013 study. The study took 24 healthy male subjects and split them into 3 groups. Each group performed a bout of resistance training and protein feeding protocol over a 12 hour recovery period ingesting 80 grams of whey protein:
|Group 1||Took 10 grams every 1.5 hours|
|Group 2||Took 20 grams every 3 hours|
|Group 3||Took 40 grams every 6 hours|
The results from the study indicated that 20 grams taken every 3 hours leads to superior results Vs the other 2 protocols, based on the anabolic signalling markers taken. This suggests that splitting your daily protein intake out throughout the course of your day may elicit better results than less frequent, larger protein feedings.
The final consideration with regards to protein intake is the maximal amount that can be utilised for MPS within a 24 hour timeframe. It’s important to recognise that the RDA (recommended daily allowance) of protein within the UK at the time of writing this article is 50 grams, which is an NHS guideline.
However we need to remember that these guidelines aren’t optimised for sports performance and muscle hypertrophy. Studies that do look into these performance factors suggest that greater amounts are necessary to maximise the post-resistance training anabolic window that typically lasts for 24 hours.
Allowing for 4 daily meals or protein feedings, with the protein dose volume above, Schoenfeld suggests (in his 2018 study) that 1.6g/kg bodyweight/day is a good amount for this demographic to strive for, which is within the upper-range of the daily dose amount found within the study above (0.4grams/kg bodyweight/meal).
Protein And Carbohydrate Vs Protein Only Feedings
It’s common practice in athlete and bodybuilding communities to supplement with protein alongside a carbohydrate post-training session due to the anabolic nature of insulin in further up-regulating MPS. For this reason athletes and bodybuilders will include a high-glycaemic carbohydrate, such as maltodextrin – in there supplement armoury after they’ve trained. However controversy remains whether the natural upsurge from dietary carbohydrates is sufficient to yield an incremental benefit beyond just protein supplementation alone or is it only insulin supplementation itself and more excessive insulin that leads to these benefits.
Despite the hypothesis there have been no studies to validate the efficacy of a combining carbohydrates with protein supplementation post-resistance training session (review) and only in vivo’ check have the synergistic effects of combining the two been apparent. The improvement In net protein balance was only noted using pharmaceutical insulin intervention (study) which if unsupervised by a medical expert carries some significant risks.
Energy Balance And Muscle Growth
Throughout this article so far we’ve only discussed protein intake and I don’t want to understate the value of carbohydrates, fats and overall energy balance when it comes to building muscle and lead you to believing that 4 protein shakes a day is the key to optimising muscle growth!
At the start of the article we discussed the role of the 3 different macronutrients and established that although energy can be derived from protein it should not be its primary purpose and there are other, better-suited macronutrients for this task, such as carbohydrates. Based on this it would suggest that a caloric surplus or an excess of calories may be more conducive to gaining muscle tissues Vs a calorie deficit or maintenance amount as it allows for amino acids to be utilised for MPS rather than for energy metabolism.
Although studies have proven that building muscle tissue is feasible in a caloric deficit, many of these studies don’t report this using already lean test subjects who regularly weight train (study) or examined the response of such an intervention on professional athletes coming back after a break (study). Conversely over-feeding, calorie surplus studies have shown that providing even fairly sedentary subjects benefit by increases in muscle mass, although inevitably accompanied by fat mass.
- Protein is only one of 3 macronutrients all vital within a healthy diet and also with their roles in energy balance, muscle protein synthesis and muscle development.
- Muscle protein synthesis – muscle protein breakdown = net protein balance. It is necessary to have a positive net protein balance in order to achieve muscle hypertrophy.
- Although national guidelines for protein intake are provided to the general public this is a broad estimation aggregating energy expenditure, body mass and demographics ranging from retirees to young athletes. Studies suggest an effective protein amount to aim for each day is 1.6grams/kg bodyweight.
- If the primary training objective at this moment in time it would be more beneficial to split this protein amount through the course of your day rather than consuming it within a restricted feeding window.
- Consuming an essential amino acid rich protein source such as whey protein post-training session can serve as an effective recovery protocol however consumption alongside a carbohydrate supplement isn’t necessary to elicit any further anabolic benefits unless overall protein intake is incredibly low in which case it may aid muscle protein breakdown.
- Although muscle development is feasible in a calorie deficit, I would not encourage an already lean athlete/lifter to use a calorie deficit if the overall object is muscle hypertrophy and an excess of calories in the range of 10/15% would be more effective.
- In order to prevent muscle protein break periods between amino acid/protein intake should be minimised, therefore breakfast and food consumption close to waking up should be prioritised if muscle hypertrophy is the primary objective.
- It can be advantageous for vegans to vary their protein sources to allow for sufficient essential amino acid intake and help with muscle protein synthesis.