1) For those looking to maximise their muscular hypertrophy gains in response to resistance training, one should aim for a daily protein intake range of between 1.6-2.2g/kg/day.
2) Single servings of between 20-40g of fast-acting WHEY protein produce the greatest increases in post-exercise muscle protein synthesis rates. But, it is not clear how this would influence long-term muscular hypertrophy gains.
3) Mixed meals, or slower acting proteins (e.g. eggs) might allow for higher protein servings per meal (up to 70g) due to their slower release into the circulation.
4) In order to maximise the bodies capacity to utilise your total daily protein intake (and hence potential muscular hypertrophy gains), spreading your protein intake across several meals MIGHT be more beneficial than having all your daily protein in one or two servings.
Ok, so over the last few blog articles I have talked about general recommendations for daily protein intakes in those who want to maximise their muscular hypertrophy gains. Given the current research, it seems that in combination with resistance training, muscle gains (for most) can be optimised with daily protein intakes at around 1.6g per kilogram body weight per day (1.6g/kg/day). However, if you are a highly advanced weightlifter or a competitive athlete (such as a bodybuilder), you might benefit from even higher daily protein intakes (approx. 2.2g/kg/day or higher!).
Well, the important thing to remember is that whatever your lifting experience, if you truly want to maximise your muscle gains in response to resistance training, then you need to make sure your giving your body what it needs to make those new muscle gains happen. If you ask me, a daily protein intake range of between 1.6-2.2g/kg/day seems to be a sweet spot for maximising gains in 99% of people looking for optimal muscle growth. Of course, there will always be those who need less or more, but given the numbers coming out of current studies, 1.6-2.2g/kg/day sounds like a safe bet for the majority. Just ensure you don’t fall into the magazine traps that say you need mountains of protein to make those gains! More is good, but too much is simply going to be waste, both metabolically and financially! Protein is not cheap.
Why Protein For Muscle Growth?
The ultimate driver for new muscular hypertrophy arises out of the constant flux between muscle protein synthesis and muscle protein breakdown. Simply put, protein synthesis is the building up of new proteins that go to produce new muscle tissue (hypertrophy!). The other side of the coin is protein breakdown. Well, you probably guessed it, it is the breaking down of proteins thus preventing your body from building new muscle tissue over time. If your goal is more gains, you need to maximise protein synthesis as much as possible and limit protein breakdown. This you can certainly do with sufficient resistance training and enough daily protein! Your job as someone who wants to build more muscle is to ensure you tip the balance away from protein breakdown towards protein synthesis. If you can do that, then you are well on your way to achieving the muscle gains you want.
Today, we have a pretty good idea on how you can maximise protein synthesis so that it remains higher than protein breakdown. While we know that resistance training causes both a rise in protein synthesis and protein breakdown, the protein synthesis response can be maximised and sustained following this resistance training with sufficient intake of daily protein. Why is this necessary to your gains? Well, by sustaining maximum rates of protein synthesis, you ensure that protein synthesis is higher than protein breakdown yielding a net gain over time in the production of new muscle proteins. These are then used to build new muscle. Given the current intake recommendations, regular resistance training combined with daily intakes of 1.6-2.2g/kg/day (as well as sufficient overall daily calories!) should allow you to maximise muscle protein synthesis responses, and thus allow for the maximal accrual of muscle building proteins. You now have your winning formula for more muscle! Resistance training + sufficient daily protein + enough overall calories. Don’t make it more difficult than this!
Ok, so we have daily protein intake recommendations. That part is pretty clear. But, one piece of the puzzle is still missing. What am I talking about? Well, something known as protein utilisation. That is, how much protein your body can actually utilise in one sitting. You can only maximise muscle protein synthesis responses if your body can access the available amino acids (from ingested protein). But, your body cannot utilise all of them at once. For instance, say you consume a daily protein intake of 1.6g/kg/day and you weigh 180 pounds. That is a daily protein intake of 1.6g x 81 kg (180 pounds) = 130g protein per day (approximately). Say you have three meals per day each consisting of 43g protein (130/3). The question is, can your body really utilise all 43 grams of protein in one sitting or will some of that simply be wasted or converted into other products? If your body can utilise all of it, then great! But if not, that 130g of protein per day is not all being utilised by the body to maximise muscle protein synthesis responses. If this is the case, then your body is getting access to less protein than it really needs, and you are missing out on potential gains. As a result of this, it is important that we know how much protein your body can utilise each meal, in order to make sure your body can make use of your total daily protein intake for muscle growth.
The Scientific Studies (Looking At Acute Protein Synthesis Responses)
A study conducted by Areta et al. (2013) investigated the influence of different amounts of a whey protein ingested (total being 80g) following a bout of resistance training (leg extension bout) over a 12 hour period in 20 resistance trained males. Group 1 (PULSE) consumed 80g of the whey over 8 servings every 1.5 hours (8 x 10g), group 2 (INT) consumed 80g of the whey over 4 servings every 3 hours (4 x 20g) and group 3 (BOLUS) consumed 80g of the whey over 2 servings every 6 hours (2 x 40g).
Following the bout of resistance training it was found that all three groups exhibited elevations in muscle protein synthesis above rest throughout the 12 hour post-exercise period. However, the INT group exhibited the greatest increases protein synthesis during the 12 hour period in comparison to the BOLUS and PULSE groups. Results suggested that 20g of fast-acting whey protein following resistance training every 3 hours is the optimal dose of protein in order to maximise post-exercise muscle protein synthesis rates. Unfortunately, we don’t know what the effect of this would have on long-term gains in muscle. But, it does give us some indication of what is happening to protein synthesis with different amounts of protein in one sitting.
Areta et al. (2013). Figures show the increases in muscle protein synthesis following a single bout of resistance training over a 12 hour period. As you can see, the intermediate (INT) group consuming 4 servings of 20g of WHEY protein over a 12 hour period resulted in the greatest increases in post-exercise muscle protein synthesis compared with the BOLUS (2 servings of 40g of protein) and PULSE (8 servings at 10g of protein) groups.
However, it’s important to keep in mind certain aspects of this study. For one, the total ingested protein over a 12 hour period was only 80g. That is less than 1g/kg/day of protein. Given that the subjects were resistance trained individuals (they need far more protein for gains!), they would have needed a lot more than 80g per day to maximise muscle-protein synthesis. Most individuals interested in resistance training and muscle growth habitually ingest more than 80g of protein per day. Another aspect to keep in mind is that the protein used was a fast-acting WHEY protein. According to Schoenfeld and Aragon (2018), due to the rapid availability of amino acids in whey, some of these are likely to be oxidised by the body resulting in a lower net protein balance in comparison to protein that is absorbed at slower rates. Slower absorption is likely to reduce the effect of amino acid oxidation making more of them available to be used for protein synthesis. As a resulted, the net protein balance is likely to be greater with slower absorbing proteins (e.g. eggs). Lastly and probably the biggest, muscular hypertrophy was not measured in this study! Given that acute increases in muscle protein synthesis following resistance training are not necessarily associated with increase in muscular hypertrophy over the long-term (Schoenfeld and Aragon, 2018), it is impossible to say whether a dose of whey protein at 20g would have also led to the greatest gains in muscle growth.
In a more recent study, Macnaughton et al. (2016) investigated the influence of 20g and 40g of ingested WHEY protein on protein synthesis following whole-body resistance training in resistance-trained males with different levels of lean body body mass. The participants were assigned to a group of lower lean body mass (<65 kg) or higher lean body mass (<70 kg) and participated in two trials in random order. In both groups, a similar post-exercise protein synthesis response was observed following ingestion of either 20g or 40g of protein. However, with both groups combined, the post-exercise protein synthesis response was significantly higher with 40g of ingested WHEY protein. These results are opposite with that of those obtained by Areta et al (2013) in which 20g of WHEY protein produced the greatest protein synthesis responses. A possible reason for this is that in the Areta et al study, resistance training consisted of only leg extension work, while in the Macnaughton et al study, whole-body resistance training was utilised. Whole-body training would have activated a larger amount of muscle mass increasing the demand for amino acids from ingested protein. However, like the Areta et al study, the impact of different ingested amounts of protein on long-term muscular hypertrophy was not tested.
Macnaughton et al. (2016). Figures show the changes in muscle protein synthesis following whole-body resistance training. In both the lower LBM and higher LBM groups, intake of 40g of protein (triangles) resulted in significant increases in post-exercise muscle protein synthesis above those taking 20g protein (circles).
In another study, Kim et al. (2015) studied the influence of different amounts of ingested protein on protein synthesis (PS), protein breakdown (PB) and net balance (NB). Since muscular development is a function of the dynamic balance between PS and PB, this is interesting to look at in the context of varying ingested protein amounts. In this study, 20 resistance trained individuals were assigned either to an exercise or resting group. In each group, individuals were given either 40g (moderate) beef-protein or 70g (higher) beef-protein (as part of a mixed meal containing carbohydrates and fat). The PS, PB and NB responses were expressed as increases above basal, fasting levels. In response to feeding at both protein levels (40g and 70g), NB was positively increased. This increase was greater in the group given 70g of protein in comparison to the 40g group, with the increases in NB occurring through primarily a decrease in PB (previous studies only measured PS). While both protein intakes led to increases in whole-body NB (anabolic response), 70g led to the greatest anabolic response. Something to note in this study is that the protein ingested came from a mixed meal. While in the previous studies, 20-40g of ingested protein resulted in the highest post-exercise anabolic responses, in this study, ingestion of 70g of protein led to the highest anabolic responses. A possible explanation for this difference is that the fats and carbohydrates of the mixed meal could have slowed the digestion and absorption of amino acids compared to fast acting WHEY protein. This would result in a slower release of amino acids into circulation from the mixed meal and hence might have contributed to the differences in anabolic responses observed (Schoenfeld and Aragon, 2018).
Kim et al. (2015). Figure shows the changes in anabolic responses (whole body protein kinetics) in response to feeding with a mixed meal containing either 40g protein (MP) or 70g protein (HP). R represents time-matched resting and X represents prior resistance exercise. In both cases, feeding with 70g of protein in a single serving resulted in the greatest increrase in net protein balance (NB). This was attributed mainly by an attentuation in muscle protein breakdown (PB) rather than muscle protein synthesis (PS).
The Link To Increased Muscular Hypertrophy?
Although these studies give us some idea of how varying protein in a single sitting is likely to influence acute anabolic responses following resistance training, they do not give us an indication of how these post-exercise anabolic responses might alter your long-term muscular growth potential. None of these studies actually measured changes in long-term muscular hypertrophy in response to changing protein amounts in a single sitting. So, what now? Well, good news is that a study by Arciero et al. (2013) helped fill in some of these gaps.
In this study, Arciero et al. (2013) compared the effects of 3 diets on lean mass changes. Overweight individuals were randomised into three groups: two high protein groups (35% of energy), protein consumed as either 3 (HP3) or 6 (HP6) meals per day and one group (15% of intake) consumed 3 meals per day of a traditional intake (TD3). Each group consumed their diets over two periods, 28 days of energy balance (BAL), followed by 28 days of energy deficit (NEG). Daily energy intakes and expenditures were similar among groups. During the BAL period, the HP3 group consumed protein at 2.27g/kg/day and the HP6 group consumed protein at 2.15g/kg/day. The TD3 group consumed protein at 0.9g/kg/day. In the NEG phase, the HP3 group consumed protein at 1.71g/kg/day, the HP6 group at 1.65g/kg/day and the TD3 group at 0.75g/kg/day.
At the end of the study it was observed that the HP6 group had significantly gained lean body mass during the BAL phase, and were the only group to maintain this lean body mass during the NEG phase. In fact, the HP3 group had significantly lost its lean body mass compared to control in the NEG phase! It is likely that the protein ingested across the 6 meals in the HP6 group (smaller per-serving protein intakes) led to greater amounts of amino acids being utilised by the body in comparison to the HP3 group. Therefore, this would allow for most of the daily protein consumed by the HP6 group to be directed towards muscle synthesis. In the HP3 group, the larger per-serving intakes of protein could have increased the chance of some of these amino acids being oxidised by the body and thus rendered unable to be utilised for protein synthesis. It is likely then that not all the daily ingested protein of the HP3 group could be used for muscle protein synthesis, leading to potentially less lean body mass accumulation during the BAL phase and also the inability to maintain lean body mass during the deficit period (NEG).
Arciero et al. (2013). Figure shows the changes in lean body mass over both study phases: BAL and NEG in response to HP3 (high protein, 3 meals), HP6 (high protein, 6 meals) and TD3 (traditional intake, 3 meals). HP6 resulted in significant increases in lean body mass during BAL, as well as retention of this lean body mass during NEG. It is likely that 6 meals a day as opposed to 3 would allow higher daily protein intakes to be more efficiently utilised by the body, thus resulting in higher protein synthesis rates and subsequent muscular hypertrophy.
So given these studies, what is the general guidance on per-serving protein intakes in order to meet a given total daily protein intake? Well, it doesn’t seem that clear cut! Using fast acting WHEY protein, it seems that single protein boluses between 20-40g appear to maximise the post-exercise protein synthesis response, while slower acting proteins (as a mixed meal with carbohydrates and fats) might allow for higher single protein boluses (potentially as high as 70g). Also, there is very little data linking these changes to muscle hypertrophy over the long-term. More still needs to be done in this area. What is clear is that splitting your total daily protein up is much better than having it in one or two larger sittings. By splitting your total daily protein up across more meals, you likely increase the body’s capacity to utilise all available amino acids from ingested protein for muscle growth. Although it is impossible to tell you how much protein you should aim for with each meal, it is clear that if you want to maximally utilise your daily protein intake for muscle growth, splitting your total protein intake up, is probably better than having it all in one or two sittings.