An Objective Review of John Kiefer’s Carb Back-Loading (Part 2)

An Objective Review of John Kiefer’s Carb Back-Loading (Part 2)

The Limitations of CBL

Some general concerns with CBL

Firstly, I don’t think that eliminating carbs all day is needed for most people, and is potentially detrimental to some, especially those who generally don’t feel good on low carbs, or athletes with high carb requirements. Given the requirement to train in the late afternoon/early evening, CBL is also not practical for those who train in the morning or afternoon. However, Kiefer does address this issue and adapts CBL for people who have work/family commitments that would clash with early evening training. To me, this somehow contradicts all what is said in the rest of the book with regards to physiology and circadian rhythms.

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An Objective Review of John Kiefer’s Carb Back-Loading (Part 1)

An Objective Review of John Kiefer’s Carb Back-Loading (Part 1)

For those that don’t know anything about the author or the book, John Kiefer holds a bachelor’s degree in Physics and Mathematics as well as a master’s degree in Physics, and is the owner of the Dangerously Hardcorewebsite. In addition to Carb Back-Loading(CBL), Kiefer has written a previous book titled The Carb Nite Solution. From his credentials and by listening to him on various podcasts and YouTube videos, Kiefer comes across as an intelligent and genuinely nice guy, so that’s where the personal judgments stop. As such, in this review, I’ll take a reasonably in depth look at CBL and examine whether the claims behind it withstand scientific scrutiny.

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BCAAs for Bodybuilders: Just the Science (Part 3)

Firstly, I’d like to apologise for my lack of activity on my blog. I have been extremely busy over the past few weeks and was lucky enough to have Matt Jones of Nutrition Condition to fill my shoes and post a couple of guest articles. As his content has been well received, you can expect to see future posts from him here.

Today, I aim to tie up the article series looking at BCAA supplementation and its effects on body composition. Before moving onto part 3, I first want to quote the summary from part 2, as it will set the stage for this post:

  • The amount of muscle mass a person has depends on the long-term relationship between muscle protein breakdown and synthesis.

  • A threshold amount of leucine of 2-3 g (~ roughly 0.05g/kg body weight) is thought to exist, with no apparent further stimulation of MPS with higher intakes.

  • This would translate to 25-37.5 g of leucine-rich protein sources.

  • Yes, you can absorb more than 30g of protein in one sitting!

  • Due to the apparent refractory nature of MPS, it would seem that eating meals spaced every 3/4-6 hours apart would optimise MPS within a 24-hour period.

  • However, it appears that there is more to muscle gain than frequently stimulating MPS; the reasons being as follows:

  1. A recommendation for higher daily amounts of protein than is likely to ‘max’ out MPS.
  2. Concept of the anabolic drive and hidden signaling pathways involved in protein turnover and AA oxidation.
  3. Real-world observations of excellent improvements in muscle mass despite theoretically ‘too high/too low’ meal frequencies.
  1. Apparent lack of effects on LBM whilst dieting with reduced meal frequencies (i.e. 1-2 meals per day).
  • It therefore seems that total protein intake is the most important variable, and how this intake is distributed, impacts body composition to a lesser degree.
  • For this reason, I don’t see any reason for meal frequency to be higher than the typical 3-4 meals per day for most people seeking optimal rates of muscle gain.
  • Though it is unknown whether moving to the ‘optimal frequency’ would be of benefit, it seems unlikely in the real world; and if so, it may only benefit the elite physique athlete looking for that 1-2% over their competition. Likewise, eating less than twice per day may compromise rates of muscle gain, however, no solid data exist to be make definitive conclusions.

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Whole proteins vs. free form amino acids: between-meal dosing

Having mentioned the practise of consuming free-form amino acids such as leucine and BCAAs on top of an existing sufficiency of protein in part 1, it is now time to get to the main point of this article and discuss the more theoretical uses of BCAAs. Having nicely set the stage by taking a look at the topic of meal frequency, the information that follows will hopefully make a bit more sense.

It was Dr. Layne Norton who originally popularised the notion of consuming free-form amino acids (e.g. BCAA) between meals. In recent years, several others have latched on to this concept and recommended their own protocols, such as dosing leucine between meals, on top of meals, between exercise sets etc.; I’m still waiting for someone to recommend snorting pure leucine!

If you remember from part 2, I talked about the refractory phenomenon associated with MPS, which has been explained by the ‘protein stat hypothesis’. It is argued that because free-form BCAAs aren't protein-bound within the matrix of the food, they are more quickly absorbed than intact proteins such as whey. It is further argued that because of this protein stat hypothesis - which indicates that an extracellular membrane-bound sensor is influenced by relative changes in amino acid concentrations as opposed to absolute concentrations - whole proteins don’t elicit a rapid rise and subsequent fall in amino acid levels, unlike their free-form counterparts. As such, Norton has advised that a BCAA mix containing 2-3g leucine (with our without additional carbohydrates – as the time course of MPS somewhat reflects plasma insulin levels) should be consumed between meals spaced 4-6 hours apart, with the aim of circumventing this refractory phenomenon associated with protein synthesis in response to the first meal. Theoretically, blunting the decrease in MPS (with a BCAA/BCAA-CHO mixture), which may occur a couple hours following the first meal, would lead to increased muscle hypertrophy over time.

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Is there any data to support this theory?

There are two main pieces of data used to support this hypothesis. The first is the already cited amino acid infusion data by Bohe et al. (2001). Secondly, Norton uses the study by Paddon-Jones et al. (2005) to justify his between-meal dosing strategy. In this trial, the authors compared the effects of supplement containing 30g of carbohydrate and 15g of essential amino acids (EAA) ingested between meals (consisting of 23.4g PRO, 126.6g CHO, 4g FAT) spaced five hours apart, with ingesting nothing between meals. The authors found that the supplement group experienced a greater overall anabolic response (nitrogen balance and fractional muscle protein synthesis) compared with the control group. This is all well and good but the problem with these findings are that the supplement group consumed 45g extra EAA (equivalent to 90g of whey or roughly 20g BCAA) and 90g extra carbohydrate than the control group. Furthermore, since total protein intake in the experimental group was 109g compared to 64 in the control group, what we’re actually comparing is an adequate intake (1.25g/kg) with an intake below the RDA of 0.8g/kg (0.74g/kg). As such, it is extremely unsurprising that a sufficient protein intake plus extra carbs is potentially more anabolic than an insufficient protein intake.

Ultimately, the practise of ingesting BCAAs between meals is largely based on amino acid infusion data - that doesn’t accurately represent oral protein ingestion – and a heavily flawed piece of research by Paddon-Jones et al. (2005). As such, between-meal dosing is an extremely optimistic strategy, based on questionable theoretical evidence. For such a strategy to prove its worth, I’d like to see a between-meal dosing strategy set up around a sufficient protein intake, in trained individuals undergoing a structured resistance programme with body composition endpoints. Will we ever see this data? I doubt it, but I can always dream! But unless it happens, I wouldn’t recommend it to my clients.

Moreover, as discussed in my last article, given the apparent lack of difference in body composition with a decent protein intake spread over 3-4 meals compared with six meals, it is highly unlikely that a slight extension of MPS with a given meal will make any meaningful differences in terms of muscle mass accrual; it almost certainly wouldn’t make a difference in terms of maintenance of muscle mass.

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BCAAs and fat loss?

As you recall from part 2, reducing meal frequency doesn’t seem to affect muscle mass retention as long as sufficient protein is being consumed. This is why intermittent fasting (LeanGains style) works very well for those looking to lose fat and retain muscle. In fact, an interesting review by Varaday (2011) concluded that intermittent calorie restriction (ICR) is just as effective as daily calorie restriction (DCR) at promoting fat and weight loss, though ICR may be more effective for retaining lean mass. However, before the intermittent fasting crowd gets too excited, it is worth remembering that the majority of the ICR studies used bioelectrical impedance (BIA) as a measure of body composition. Anyone familiar with BIA knows that it’s inaccurate at the best of times.

Therefore, it appears that an optimal meal frequency whilst dieting is the one you can best stick to. Because of this, attempting to increase the number of stimulations in MPS, or extend this process, during dieting seems a futile one.

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What about their caloric efficiency?

Given that BCAAs are the only amino acids that stimulate protein synthesis, another rationale for the use of BCAAs whilst dieting is due to their greater caloric economy in comparison to whole protein sources. In other words, if your aim were to get 3g of leucine in a given meal, ingesting whole protein food such as whey would require about 25g (100kcal), whereas 6g (24kcal) of BCAAs would provide the same amount of leucine.

By the same logic, if things were only as simple as getting enough leucine to max out MPS at each meal (~4-6g of most brands of BCAAs), we would theoretically only need 24-36g of BCAAs per day to cover protein requirements. However, it’s no use having leucine to initiate protein synthesis if there is no protein (i.e. other amino acids) to actually carry on this process. What will basically happen is that things will short circuit, meaning that MPS may begin but then stop soon after. A quote from a review by Balage & Dardevet (2010) on the topic sums this up nicely:

“There is some evidence that long-term leucine availability is sufficient to improve muscle mass or performance during exercise training. However, it needs to be associated with other amino acids to be efficient (for example, through leucine-rich proteins).”

This wouldn’t seem to be a problem for the between-meal dosing of BCAAs since there are already other amino acids in circulation. The aim of this strategy isn't to stimulate MPS using BCAAs by themselves; rather, it is to extend MPS.

However, like a complete protein, it also appears that an EAA mixture may optimise MPS. As such, consuming sufficient whole protein the majority of the time and then replacing around-workout whey protein with BCAAs may also have the intended benefit (i.e. optimal MPS stimulation) but with greater caloric efficiency. For example, whey contains roughly 25% BCAA, so assuming someone consumes 30g of whey protein pre and post training, this would amount to 60g of whey (240kcal), whereas isolated BCAAs will account for 15g total (60 kcal), a saving of 180kcal per workout day. If this person trained four times per week, this would be a saving of 720kcal per week, just over 100 kcal per day.

However, I honestly can’t see why someone would want to save calories by reducing protein intake in the first place, never mind go to all that effort just to save themselves 100kcal per day. The same reduction could be achieved by sticking with whey and reducing fat by 11g or carbohydrate by 25g per day, or a combination of the two. Not only will this save you money, you’ll get as much BCAA as well as all the other essential and non-essential amino acids (which may impart added benefit). You’ll also get the

I don't know about you but I'd prefer more to a meal than this whilst dieting.

potentially therapeutic compounds contained in whey such as immunoglobins and lactoferrin, as well potentially anabolic properties of whey independent of its constituent amino acids. Finally, you’ll likely experience greater satiety with whey compared to isolated BCAAs (something that would benefit dieters). In clinical research, BCAAs have been used to stimulate appetite in populations at risk for muscle wasting. The mechanism to explain why this is the case involves BCAAs competing with tryptophan for entry into the brain, thereby reducing the production of a satiating neurotransmitter, serotonin.  As such, it is ironic that the same supplement many take for dieting purposes may actually make dieting a more difficult experience than it needs to be. Conversely, the satiating effects of whey protein are well documented.

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Conclusions & Practical Recommendations

In summary, form part 1 of this article series, I discussed BCAA supplementation on top of a pre-existing sufficiency of protein and came to the conclusion that BCAAs would seem to make little, if any, difference in terms of muscle gain. In part 2, the stage was set for the current article in where I discussed the issue of meal frequency, the conclusion of which is outlined at the beginning of this article.

In this final instalment, we dug deeper into the more theoretical arguments for BCCA supplementation. Specifically,  the claims behind the between-meal dosing of BCAAs and how this might positively impact on muscle hypertrophy were examined, as well as their potential benefits whilst dieting.

The protocol advised by Layne Norton involves using doses of BCAAs likely to maximally stimulate MPS (~4-6g) in between meals spaced 4-6 hours apart. However, this strategy is largely based on amino acid infusion data and a deeply flawed study with highly predictable findings. Therefore, the practise of between-meal BCAA doing is essentially a hypothesis (that extending MPS slightly will lead to greater gains in strength/hypertrophy over time) based on a hypothesis (that such dosing protocols will actually extend MPS  under more realistic dietary conditions) based on a hypothesis (that the protein stat hypothesis holds true), thus extremely optimistic.

In terms of muscle retention whilst dieting, the frequency of protein ingestion doesn’t seem to make a difference as long as sufficient total protein is being consumed, meaning that between-meal dosing is irrelevant under dieting scenarios, at least in terms of optimising MPS on a meal-per-meal basis. As such, the caloric economy of BCAAs is their main attraction for dieters. However, at best, this tactic will save you a few calories, possibly at the expense of hunger, other beneficial properties associated with complete protein sources and money. It is much less hassle, cheaper, and potentially more beneficial to cut calories from either fat or carbohydrate.

Layne Norton may indeed be ahead of the game when it comes to his suggested BCAA protocol taken between meals separated by 4-6 hours. However, when compared to a sufficient protein intake (2.5-3g/kg) spread over the typical 3-4 meals (as suggested in part 2), I can’t see how this tactic could be much more beneficial, if at all. To quote Alan Aragon speaking about Layne Norton about the very topic:

“it’s crucial to realize that [Layne’s BCAA protocol] might be miniscule and not worth the effort or expense for non-competitive populations. In repeated personal communication, he has admitted to me that this tactic is done in attempt to clinch a very small edge to win. As a top-level, drug-free competitor, it’s justifiable to exploit all hypothetical nutritional means within reason in order to conjure the last bit of potential.”

As such, unless you are a physique competitor in search of that extra 1-2% (if it exists), it may be feasible to experiment with such tactics in the effort to gain an advantage. For the rest of us (>99.99 of people) looking to get in better shape, I see little point in supplementing with BCAAs. Instead, I’d urge you to save your money and invest in what delivers. That is, consume a sufficient amount (2.5-3g/kg) of high quality protein that will put you in good stead for making solid gains in the gym, whilst constantly hitting other macronutrient targets across a range of minimally processed foods. From there spread this intake evenly over the typical 3-4 meals, with two of these protein-containing meals placed within windows 90-120 minutes prior to and after weight training. If you have difficulty in reaching such intakes with solid proteins, opt for a decent whey protein concentrate or isolate in order to make up the difference. Speaking of weight training, focus on adding manageable weight in the main compound movements. Not only will this save you money, you will surpass the vast majority of people who use isolated BCAA supplements.

BCAAs for Bodybuilders: Just the Science, Part 2 (Meal Frequency)

In part one of looking at what part BCAAs play in bodybuilders’ diets, I discussed what BCAAs are, their unique role in protein synthesis, as well as what foods they are contained in and in what percentages. On a gram per gram basis, you would get more than double the amount of BCAAs for your money if you opt for a high quality whey protein isolate than if you were to purchase isolated BCAA; as well as the benefit of all the other essential and non-essential amino acids. As such, I see no use for BCAAs unless they prove to be beneficial despite a sufficient protein intake.

Given the controversy that surrounds their use on top of a sufficient protein intake, I examined the limited human trials on the very matter and came to the conclusion that BCAAs would seem to make little, if any, difference in the presence of sufficient protein. In the absence of sufficient human data looking at body composition endpoints, these conclusions are somewhat speculative. However, my personal observations support my contention that they provide no benefit to those hoping for more muscle and less fat.

As I feel that the available human data doesn’t sufficiently answer the main question behind this article series, I will dig a little deeper and see if more mechanistic and theoretical arguments shed any more light on this matter. I will spend this post looking at the issue of meal frequency and how it pertains to maximising anabolism, as it will lay the foundations for the discussion in the third and final part, in which I will dissect the claims made about between-meal BCAA dosing strategies, and their use whilst dieting.

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Maximising anabolism: the role of leucine in muscle protein synthesis.

 To quote myself from my protein requirements article:

“The amount of muscle tissue in the human body remains fairly stable over time. However these tissues are undergoing a continuous process of breakdown and resynthesis; these processes are referred to as protein turnover. The amount of muscle mass a person has depends on the long-term relationship between muscle protein breakdown and synthesis. For example, if muscle protein synthesis exceeds breakdown, there will be an increase in the amount of that protein. Protein turnover is mediated by several factors including hormones (testosterone, growth hormone, thyroid, insulin, glucagon & cortisol), caloric intake, amino acid/protein availability and training. The largest factors that influence skeletal muscle metabolism are eating and training… This may lead one to assume that the simple act of eating a load of protein will lead to gains in muscle mass. However, this isn’t the case due to a process called diurnal cycling, whereby net protein synthesis following a meal is matched by an increased protein breakdown when food is not being consumed… diurnal cycling tends to keep the body at a stable amount of muscle mass. However, when [resistance] exercise is introduced, it basically “forces” the body to store more protein (assuming sufficient protein and overall caloric intake that is).”

As such, it would appear that maximising daily dietary-induced muscle protein synthesis (MPS) would yield the greatest benefit in terms of maximising the potential for muscle gain. Theoretically, it seems that maximising the anabolic response via eating, revolves around the leucine content of a protein containing meal, and the frequency of which such meal is eaten (i.e. meal frequency; technically protein frequency).

Of the three BCAAs, it is leucine that plays the major role in initiating MPS via the stimulation of the biochemical sensor named the ‘mammalian target of rapamycin’ (mTOR). Relating to the ingestion of protein, a threshold amount of leucine of 2-3 g (~ roughly 0.05g/kg body weight) is thought to exist so that changes in plasma leucine concentrations maximally stimulate MPS. Intakes above this threshold (~8 g leucine) do not appear to have any further stimulatory effects on MPS. From table 1 (in part 1), this would translate to 25-37.5 g of leucine-rich protein sources (e.g. whey, eggs and meat). It is worth highlighting that these hypotheses were developed using rodent models based on acute human data by Paddon-Jones et al. and Tipton et al.. However these notions do have some solid grounding, with more recent human data seeming to support them. This would also seem to be where the ‘broscience’ myth of being only able to absorb 30g (or other random amount) of protein came from. If this were the case, then you wouldn’t be reading this today.

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Frequency of meal/protein ingestion

Now that we know roughly how much protein is needed at each meal in order to optimise MPS, the question remains of how frequently you need to eat to maxmimise MPS, with the hope setting yourself up for maximal muscle gains.

Before we get into that, I want to quash the myth that eating more frequently helps someone to stay lean/lose more body fat by “stoking’ the metabolic fire” or whatever other silly reason is given. It makes no difference how many meals are consumed as long as total kcals (and macros) remain the same. Though the digestion of food requires energy (Thermic effect of food; TEF), TEF is directly proportional to the macronutrient content of a meal. For example, it would take twice the amount of energy to digest a 1000 kcal meal than if you were to eat only half of that meal. Therefore, you can see why splitting food intake into more meals will have no impact whatsoever on metabolic rate. As such, strictly speaking of fat loss, the optimal meal frequency is the one that suits an individual most in terms of hunger, routine, practicality etc.

Now that I’ve got that out of the way, meal frequency gets a little more complicated when talking of muscle gain; at least in theory. It would appear that increasing the frequency of which these maxmimal stimulations of MPS occur (i.e. increased meal frequency) is beneficial for those looking to build muscle. Therefore, logic would dictate that one should eat threshold amounts of protein as frequently as possible if the aim were to maximise MPS within a given 24 hour period. Unfortunately, things aren’t that simple.

Data from rodent and human amino acid infusion studies have demonstrated that MPS lasts for approximately two hours before returning to baseline, despite elevated amino acid levels in the blood. More recently, data from Layne Norton’s lab has shown that consuming a complete meal delays and extends its effects on MPS to roughly three hours, peaking at 45-90 minutes.  It therefore appears that there is a refractory response to protein synthesis (i.e. MPS decreases despite the presence of the initiating stimulus, amino acids) and that once MPS is maximally stimulated following a protein containing meal, further stimulation will not occur by simply ingesting more protein.

An explanation for this resistance to further stimulation of MPS comes from the ‘protein stat hypothesis’, which suggests that an extracellular (outside of the muscle cell) membrane-bound sensor is influenced by relative changes in amino acid concentrations as opposed to absolute concentrations. Specifically, the change from a lower concentration of AAs to a higher one is what seems to drive MPS, meaning that this whole process needs time to “reset” before MPS can be triggered again with the next meal. It therefore seems that spacing meals and allowing blood AA levels to drop, would maximise MPS in subsequent feedings.

Based on this refractory phenomenon, in his aptly titled The Protein Book, Lyle McDonald poses two questions in the attempt to negotiate an ideal meal/protein frequency:

  1. Is it possible to eat too frequently?

  2. How long will a typical meal maintain the body in an anabolic state?

The first question is getting at how long it takes for the processes discussed above to “reset”, before a subsequent meal will max out MPS. The second question refers primarily to digestion rates (i.e. how long after a meal are nutrients (e.g. amino acids) being released into the blood stream?).

Looking at the first question, based on the available data, it would seem that 3-4 hours would theoretically be the minimum time that should pass between meals if you wish to maximise MPS in the second meal. With regards to the second question, there are plenty of data points to determine roughly how long it takes for proteins to be digested. It has been shown that even a modest meal (37g PRO, 75g CHO, 17g FAT) is still releasing nutrients in to the blood stream five hours later. Slowly digesting proteins such as casein (touted as the good old “pre-bed” source to stop you waking up with no muscles) may still be releasing AAs into the blood 7-8 hours, or more, after ingestion!

"My buddy got swole by eating every 3 hours!"

However, meals consumed by most people looking to gain muscle, often contain more protein and total nutrients than in the aforementioned studies. Therefore, taken together, a VERY conservative time limit of six hours passing between meals, during waking hours, would seem reasonable. Incidentally, these recommendations of eating every 3/4-6 hours are similar to those of Layne Norton, who advocates consuming threshold doses of protein containing meals 4-6 hours apart, interspersed with a BCAA/CHO solution with the aim of circumventing this refractory phenomenon associated with MPS (more on this in the next article!). So, eating every 3-6 hours while awake (assuming eight hours of sleep) would yield a meal frequency of roughly 3-6 meals per day.

Since I previously recommended an intake of between 2.5-3 g/kg of bodyweight for bodybuilders/strength athletes, using my body mass as an example (77 kg), this equates to a protein intake of between 192.5-231 g per day. Using the higher end as an example, at a fairly standard frequency of 3-6 meals, daily protein intake would equate to roughly 38.5-77g per meal on average. At the bottom end of this intake, 38.5 g of any high quality protein would adequately cover the upper-end of the 2-3 g leucine threshold for maximising the anabolic response to a given meal (see table 1). In theory, it would seem that splitting the intake over six meals rather than three would lead to better gains in muscle mass due to 6 vs. 3 stimulations in MPS per day. In reality things aren’t that straight forward. If it were, using this example, six stimulations of MPS per day SHOULD lead to double the rates of muscle growth than three.

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This is where things get confusing

For example, 25g of a whey protein isolate (WPI) (see part 1) would provide roughly 3g of leucine (the maximum amount likely to maximally stimulate MPS in anyone). If someone were to ingest 25g of WPI every three hours (six ingestions per day), then MPS should theoretically be maxed out in a day, with an intake of only 150g of protein. If we take a 100kg rugby player, this would provide an intake of 1.5g/kg per day of protein. This is half of the upper end of what I advocate for strength/power athletes, and is also on the low side of the already conservative values cited in research. What’s going on?

Though I’ve used somewhat of an extreme example to illustrate my point, it seems that there is more to building muscle than just hitting these leucine thresholds on a meal per meal basis. In my opinion, total protein intake is the more important variable in terms of muscle mass accrual, compared with how it is split up throughout the day; at least in terms of a typical meal frequency encountered by those who have more to worry about than prepping half a dozen Tupperware boxes per day.

To quote Lyle McDonald from The Protein Book on the matter,

“Optimizing the function of other important pathways [besides MPS] of AA metabolism would very likely raise protein requirements even further.”

Indeed, as alluded to in my article on protein requirements, increased levels of AA oxidation (likely due to intakes in excess of these leucine thresholds), may be involved in the overall “anabolic drive”, meaning there are likely to be “hidden” signaling pathways that contribute to muscle anabolism that we are not yet aware of. As such, increased AA oxidation may actually provide benefit as opposed to its traditional view as being a wasteful process. Essentially, we know that more protein is better (hence my recommendations), but science hasn't figured out the whys yet.

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Searching for the optimal meal frequency

Since most people tend to eat their total daily protein across 3-4 meals, an important question is whether splitting an existing protein intake across an additional 2-3 meals, will provide any benefit in terms of muscular hypertrophy. In the May 2012 issue of his monthly research review, Alan Aragon (I’d abbreviate to AA but then you may mistake him for an amino acid) attempted to answer this question with a combination of limited available data as well as his own observations in the field. In this article, he states:

“Given a diet with an abundance of high-quality protein from varying sources, frequency and proportional distribution of protein doses within day are not likely to make any meaningful impact unless extremes are pushed. It’s rare for anyone with the primary goal of muscle growth to eat twice a day (or less)… It’s reasonable to hypothesize that consuming a solid, mixed, protein-rich meal every 4-6 hours while dosing BCAA between meals could result in a higher rate of muscle growth than getting all of your protein in a single meal each day. However, I see quite a grey area when [Layne] Norton’s protocol is compared with 2-3 meals containing a matched total of high-quality protein (minus the BCAA or leucine threshold dosing between meals).”

Aragon then goes out on a limb and states that:

“even in the case of an IF-type [intermittent fasting] of scenario where only one or two meals per day are consumed, I would still challenge that any meaningful compromise in muscular growth is speculative in the absence of data."

Though seemingly counter-intuitive, there is actually nothing incorrect about Aragon's claims, despite the criticisms of IF from many experts; the scientific data just isn’t there (yet).

Despite some of its questionable conclusions, according to the ISSN position stand on meal frequency, a reduced meal frequency doesn’t appear to compromise lean body mass (LBM) under hypocaloric conditions in the presence of a sufficient protein intake. That is, eating 10 times per day as opposed to once or twice per day doesn’t seem to make a difference with regards to the sparing of LBM on a diet (assuming you're getting sufficient protein that is). If it were true that maximising MPS following the protocols outlined above (i.e. total protein spread evenly across six meals per day) would result in maximal rates of muscle mass accrual, then it raises the question, ‘why doesn’t reducing meal frequency appear to have a negative effect on LBM whilst dieting?’

It is my contention that as long as sufficient amounts of high quality protein are consumed, then spreading protein intake from 3-4 meals to 6 meals is a waste of time and effort for the vast majority of people. This increase in protein frequency may be of benefit to the elite physique athlete, but I’m yet to see how this could result in more than trivial amounts of muscle mass; quantities of which are unlikely to be detected in research (especially with modern-day assessments of body composition). On a related note, I’m not certain that the concern of eating too frequently is a valid one either. The majority of bodybuilding champions eat upwards of six, sometimes 10, meals per day, and they don’t seem to be held back by it. By the same token, there are many proponents of IF who have achieved excellent improvements in body composition despite a meal frequency of perhaps 1-3 protein feeding per day. With respect to my last point, there is at least some data suggesting that going below 2 protein feedings per day might hinder muscle gains.

So, with all things considered, I think that a minimum of three protein feedings per day would be ideal and easily achievable for >99.9% of people looking to optimally gain muscle mass.

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Summary

To briefly summarise:

  • The amount of muscle mass a person has depends on the long-term relationship between muscle protein breakdown and synthesis.
  • A threshold amount of leucine of 2-3 g (~ roughly 0.05g/kg body weight) is thought to exist, with no apparent further stimulation of MPS with higher intakes.
  • This would translate to 25-37.5 g of leucine-rich protein sources.
  • Yes, you can absorb more than 30g of protein in one sitting!
  • Due to the apparent refractory nature of MPS, it would seem that eating meals spaced every 3/4-6 hours apart would optimise MPS within a 24-hour period.
  • However, it appears that there is more to muscle gain than frequently stimulating MPS; the reasons being as follows:
  1. A recommendation for higher daily amounts of protein than is likely to ‘max’ out MPS.

  2. Concept of the anabolic drive and hidden signaling pathways involved in protein turnover and AA oxidation.

  3. Real-world observations of excellent improvements in muscle mass despite theoretically ‘too high/too low’ meal frequencies.

  4. Apparent lack of effects on LBM whilst dieting with reduced meal frequencies (i.e. 1-2 meals per day).

  • It therefore seems that total protein intake is the most important variable, and how this intake is distributed, impacts body composition to a lesser degree.
  • For this reason, I don’t see any reason for meal frequency to be higher than the typical 3-4 meals per day for most people seeking optimal rates of muscle gain.
  • Though it is unknown whether moving to the ‘optimal frequency’ would be of benefit, it seems unlikely in the real world; and if so, it may only benefit the elite physique athlete looking for that 1-2% over their competition. Likewise, eating less than twice per day may compromise rates of muscle gain, however, no solid data exist to be make definitive conclusions.

I will get straight in to things in part three and discuss the issue of dosing BCAAs between meals as well as their use whilst dieting. If you’ve been paying attention in this article, you can already see where things are going…

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Protein requirements for people who will never settle for being average

With over 50 years of research, we are still debating over how much protein you actually need for given types of exercise (i.e. weight training vs. endurance training etc.). On the conservative side of protein intakes we tend to have the mainstream nutritionists who maintain the idea that athletes don’t need to consume protein in excess of the recommendations outlined for non-athletes. On the other side of the argument are the athletes and bodybuilders themselves who have for several decades maintained the idea that they need to consume greater amounts of protein than the average person.

As research exists for both sides of the argument, scientists tend to have mixed views on how much protein a person actually needs, whether they are sedentary, in training or a professional athlete.

In this article I will address the popular, yet often misunderstood, topic of protein requirements. I will examine the research from both sides of the argument, as well as what I’ve seen work in practise, and present my own recommendations.

The basics of protein metabolism

The amount of muscle tissue in the human body remains fairly stable over time. However these tissues are undergoing a continuous process of breakdown and resynthesis; these processes are referred to as protein turnover.

The amount of muscle mass a person has depends on the long-term relationship between muscle protein breakdown and synthesis. For example, if muscleprotein synthesis exceeds breakdown, there will be an increase in the amount of that protein.

Protein turnover is mediated by severalfactors including hormones (testosterone, growth hormone, thyroid, insulin, glucagon & cortisol), caloric intake, amino acid/protein availability and training. The largest factors that influence skeletal muscle metabolism are eating and training.

Eating a meal

Theprimary factors influencing protein breakdown and synthesis following the consumption of a meal are the concentrations of insulin andamino acids in the blood. With regards to protein synthesis, the essential amino acid (EAA) content of a meal plays a significant role in promoting synthesis; insulin plays a smaller role. In a more direct role, insulin increases amino acid transport into skeletal muscle. Assuming sufficient amino acids are available, only small elevations in insulin are required to maximally stimulate protein synthesis. Regarding protein breakdown, consuming a meal would appear to decrease protein breakdown by increased amino acid availability as well as the presence of insulin.

The take home message here is that insulin combined with increased amino acid availability, results in net protein gain. This may lead one to assume that the simple act of eating a load of protein will lead to gains in muscle mass. However, this isn’t the case due to a process called diurnal cycling, whereby net protein synthesis following a meal is matched by an increased protein breakdown when food is not being consumed. So the more protein someone eats and the more they store in the day, the more they break down at night. This process is thought to provide amino acids from the ingested food more evenly over a 24-hour period.

The effects of training

In untrained people diurnal cycling tends to keep the body at a stable amount of muscle mass. However, when exercise is introduced, it basically “forces” the body to store more protein (assuming sufficient protein and overall caloric intake that is).

The type of training dictates how dietary protein is used to synthesise new proteins in the body. Following weight training both protein synthesis and breakdown are increased, though breakdown is stimulated to a greater degree, meaning that the body is likely to be in a catabolic state following weight training. The provision of protein/calories around the workout will shift the body into an anabolic state “forcing the body to store protein at a higher level (increase muscle mass).

In contrast, endurance exercise results in a different effect on skeletal muscle. Instead of increasing the size of contractile proteins, it mainly stimulates the synthesis of mitochondrial enzymes within the muscle, contributing to an increase in energy production (oxidative capacity) during such activity.

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The recommended daily intake of protein

Challenging the RDA

According to thelatest dietary reference intake (DRI) in 2005, the amount of protein that all adults should consume on a daily basis (RDA) is 0.8 grams per kilogram of bodyweight (0.8g/kg). Based on nitrogen balance data, this intake is estimated to cover the basic needs of 97-98% of individuals. The authors of this report state that this intake is suitable for both sedentary individuals as well as endurance or strength athletes: “In view of the lack of compelling evidence to the contrary, no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise.”

In contrast, the most recent scientific literature would recommend intakes from 1.2-2.2g/kg for strength and endurance trained athletes. Even for untrained individuals the RDA would seem insufficient for some individuals. For example, a 14 week study by Campbell and colleagues observed that subjects (55-77 years) consuming the RDA for protein (0.8g/kg) experienced significant muscle loss in the mid-thigh area, despite consuming calories to maintain bodyweight. Since this study was published in 2001, the authors of the latest DRI report had sufficient time to amend these recommendations based upon the most recent literature. Either sincere ignorance or laziness may account for this. In keeping with the latter, this may also explain why the RDA for protein hasn’t changed for several decades.

While the RDA may meet the need for the majority of sedentary individuals in energy balance, this amount is simply inadequate for strength and endurance athletes as well as for the elderly or dieting individuals, regardless of training status. Given the lower digestibility and inferior quality of many grain and legume (i.e. beans and nuts) proteins, vegetarians and vegans may need to consume protein in the excess of the RDA to compensate.

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Protein requirements for strength and endurance athletes

An early review article by Lemon in 1991 recommended protein intakes of 1.2-1.4 g/kg for endurance athletes and 1.4-1.7 g/kg for strength/power athletes; for athletes competing in sports where a mix of these training methods is warranted (i.e. MMA, Rugby etc.), the upper limit recommended for strength athletes has been suggested to cover protein needs.

These increased requirements for endurance and strength athletes occur for different reasons. During intense aerobic activity (i.e. running or cycling) amino acids, namely the branched chain amino acids (BCAAs), have been shown to account for roughly 5-10% of total energy cost of the activity; this percentage may increase further when muscle glycogen is depleted. In contrast, amino acids provide little energy during strength training. Instead, the increased need for protein comes from the repair of damaged muscle tissue as well as the synthesis of new muscle proteins.

Lemon’s conclusions have since been criticised by Millward, mainly because of the inherent limitations associated with nitrogen balance (the technique used to deduce protein needs). Indeed, the errors associated with estimating nitrogen losses may accumulate and lead to an overestimation of true protein requirements. Additionally, nitrogen balance doesn’t consider the dynamic processes of protein turnover, rather, the amount of nitrogen going into the body (food and drink) minus nitrogen losses form the body (i.e. urine, faeces, sweat etc.).

Millward has also cited earlierwork suggesting that endurance training may actually lower protein requirements compared with untrained individuals, due to an adaptive downregulation increasing the re-use of amino acids. Indeed, in a widely cited study, it was demonstrated that nitrogen balance was negative at the start of an exercise training programme, but returned to equilibrium after a period of accommodation. This occurred despite a constant daily protein intake. Following the period of accommodation, no increase in protein intake was necessary to maintain a stable nitrogen balance.

However, while more recent research has suggested that this may be the case for individuals performing low intensity endurance exercise, endurance athletes (and the more serious recreational athletes) who perform many hours of high intensity exercise per week, would seem to benefit from higher intakes than their untrained counterparts. Furthermore, for the evidence suggesting an increased efficiency of amino acid re-use as protein intake decreases, nitrogen balance may be attained with a compromise in some physiologically relevant processes such as enzyme upregulation or capailliarisation following endurance training. It would therefore seem that while training may improve protein retention (thus achieving a neutral nitrogen balance), this might hinder potential performance enhancing adaptations associated with endurance exercise.

For athletes wishing to gain lean body mass, it has been shown that whole body and muscle protein synthesis rates are greater with increasing protein intakes. In one study, experienced weightlifters were fed either 1.2 or 2.1 g/kg of protein per day for six weeks. In the group that ingested the higher amount, gains in lean tissue mass increased significantly, whereas there was no change in the 1.2 g/kg group.

These results clearly refute the notion that trained individuals don't need more protein than the average person. However, these results still give no idea what an optimal intake might be in this case; just that 2.1 is better than 1.2 g/kg of protein.

Despite the above study, not all evidence supports the idea of increasing amounts of ingested protein leading to greater muscle mass gains. A study by Tarnopolsky and colleagues examined nitrogen balance, body composition and urea excretion during a habitual 10-day period followed by an altered protein intake for 10 days. However, by virtue of slow rates of muscle mass gains, with an altered protein intake period of 10 days, it is unsurprising that there were no changes in lean body mass seen among individuals in this investigation. A further study by the same lead researcher indicated that a protein intake of 2.4 g/kg was not superior to that of 1.4 g/kg in terms of lean body mass gain, among trained strength athletes. However, given the short (a few weeks) study period, it is possible that muscle gain was occurring in the higher protein group, and that the change was too small to be measured with existing body composition techniques.

From a separate standpoint, it has also been argued that the debate over protein requirements is pointless in the first place since the majority of both strength and endurance athletes habitually consume amounts in excess of the recommendations outlined by Lemon. While this is generally true, some athletes, particularly female athletes, have been shown to consume inadequate amounts of protein.

Why all the conflicting viewpoints?

Since the original review article on protein requirements by Lemon in 1991, much data has since been published regarding the interaction of protein and exercise. However, despite these advances, more questions remain unanswered than have been solved. Limitations in research methodology certainly confound results (i.e. nitrogen balance). Participant selection, their adaptation to the protein intakes during their respective studies, training status, nutritional status and exercise intensity further contribute to the discrepant findings, which ultimately to lead to different interpretations. As mentioned previously, short study periods are also far from realistic in order to observe true lean body mass changes with differing protein intakes.

Perhaps the most logical interpretation of the research findings thus far comes from the authors Tipton & Wolfe. Probably their most important point is that athletes and coaches are not interested in the academic debates surrounding protein requirements, rather, they are interested in the specific amount of protein that will optimise athletic performance. This is where the research has often fallen short; instead of looking at performance endpoints following the ingestion of different amounts of protein, studies have tended to simply examine protein “requirements”. That is, the daily amount of protein that supports net protein balance, measured via nitrogen balance or examining leucine kinetics. Indeed, a protein intake that stimulates optimal physiological adaptation (i.e. capillary and enzyme upregulation, muscle hypertrophy and total oxidative capacity of the muscle) as well as immune surveillance, may be in excess of the current recommendations outlined for strength and endurance athletes. It is therefore important to distinguish the difference between a protein “need” of a given athlete, and the amount of protein that will stimulate maximal “adaptations” leading to optimal performance.

A further point the authors make surrounding protein requirements is that the definition of a protein requirement is context specific. For example, the amount of protein that an strength power lifter is to consume to maintain lean body mass will be different to that of a bodybuilder trying to gain lean body mass or that of a bodybuilder aiming to lose body fat while maintaining their muscle mass. The list goes on…

This article also highlights the fact that a daily protein intake of 2.5-3 g/kg for strength and power athletes is not harmful and would appear more than is necessary for protein synthesis, any excess would simply be oxidised. As a slight tangent, it is worth noting that some authors feel that increased oxidation may contribute to the anabolic drive of the body. Given the scant and limited duration data on performance/bodycomposition endpoints, erring on the side of too much rather than too little dietary protein may be the best approach for strength and/or hypertrophy. Perhaps the single greatest risk of ingesting too much protein is the displacement of other macronutrients, namely carbohydrate, which might hinder high intensity exercise. However, since intakes of ~6400 kcal have been reported in strength athletes, an intake of 2.5 g/kg would only account for 14% of their daily intake.

Since endurance athletes are typically less interested in gains in lean body mass, or body weight for that matter, the upper limit for protein consumption would be lower than that for strength/ power athletes. Tarnopolsky’s research group hasdemonstrated that protein intakes above 1.7 g/kg result in the excess being oxidised. Therefore, there appears to be no reason to suggest protein intakes above 2 g/kg for endurance athletes. Similar to the strength/power athletes, this intake is unlikely to impede on carbohydrate or fat intakes. For example, if an endurance athlete consumes 3000 kcal per day, an intake of 2 g/kg would only account for 18% of total intake. Endurance athletes typically consume more total energy that this anyway. As mentioned earlier, athletes competing in team sports (i.e. soccer, rugby, basketball etc.), whose training consists of both endurance and strength work, the lower intake recommended for strength athletes (2.5 g/kg) would be a good starting point. However if hypertrophy is required, they maybe should consider the upper limit of 3 g/kg.

To clarify, based on these data, I feel that daily protein intakes of 2.5-3 g/kg appear optimal for strength/power athletes as well as many team sport players, or any athlete that combines both strength/hypertrophy and endurance training. For drug fuelled athletes looking to maximize muscle gains, more protein than 3 g/kg may be required (intakes in excess of 4-5 g/kg have been reported anecdotally). However, this is beyond the scope of this article. For endurance athletes, where muscle hypertrophy is  generally undesired, daily protein intakes of 1.7- 2 g/kg have been suggested to maximise the adaptive response to such training.

Protein requirements when dieting

Given the significant protein sparing effect of energy intake, when athletes need to make weight, reduce unnecessary fat or when physique athletes need to prepare for a show or photo shoot, increasing protein above the recommendations outlined here are imperative to avoid muscle loss. As calories are reduced, the body retains less protein and more is used to supply energy (via gluconeogenesis); therefore, the body needs more.

It has been demonstrated that in overweight, non-trained individuals, protein intakes almost double that of the RDA (~1.5 g/kg) are required to maintain lean body mass losses during calorie restriction. Bodybuilders have successfully used this practice over the last 40 or so years by increasing habitual protein intakes by roughly 150% in the pursuit of rapid fat loss while maintaining muscle. However, for most performance athletes, such a drastic calorie reduction isn’t optimal. Instead, a more modest fat reduction is optimal for several reasons (perhaps, most importantly, as carbohydrate intake will suffer, thus hindering training performance).

Given the relatively high protein intakes recommended above, there would be little need to increase protein too much over the outlined recommendations. Without any scientific data to go by, the lower end of the protein intake should be replaced by the upper amount suggested. For endurance athletes, this would be an intake of 2 g/kg of protein per day. If fat loss is achieved in a preferable manner (i.e. gradually), these intakes will minimally impede of carbohydrate intake. Thus, the athlete is able to maintain performance to a degree, while consuming enough protein to cover all needs and minimising muscle loss. For physique athletes aiming to reach the limits of leanness (i.e. 3-5% body fat for men and 9-12% for women), then increasing protein intakes in excess of these recommendations, may limit muscle loss to a greater extent.

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Summary and application

In summary, well it does appear that the RDA of 0.8g/kg of protein may be enough for most untrained individuals (assuming they are in nitrogen balance), this simply isn’t enough for some untrained populations (i.e. older or dieting individuals).

There is plenty of research highlighting that the RDA is indeed insufficient for trained individuals, with original protein intake recommendations of 1.2-1.4 g/kg for endurance athletes and 1.4-1.7 g/kg for strength/power athletes. However, given that research exists supporting both the consumption of more and less than these original recommendations, the debate over protein requirements is likely to continue for decades.

More importantly, coaches and athletes are less interested in these academic debates. They simply wish to know what intake will optimise performance. However, until more valid performance endpoint research is conducted, these questions will remain unanswered. Furthermore, given the methodological difficulties in carrying out such research, this won’t be any time soon. With that being said, there does appear to be sufficient research to draw out reasonable protein intake recommendations for athletes. This, combined with my personal observations in the field, I am able to outline some specific recommendations depending on your type of training and body composition goals (see table below).

Given that protein intakes at the higher ends of my recommendations are unlikely to have negative impacts on health and performance, the best approach may be to err on the side of consuming too much, as opposed to too little. The positive effects on body composition (i.e. fat loss and muscle gain) of higher protein diets compared to calorie-matched lower protein diets, would also support this notion.

Outlined below are the intakes that I ultimately recommend. These intakes should ensure optimal adaptations as well as allowing room for the consumption of other important macronutrients. For regular gym-goers, the lower end of the recommendations will suffice.

Athlete type

Units

General intake

Dieting intake

Strength/Power

g/kg

2.5-3

3

g/lb

1.1-1.4

1.4

Endurance

g/kg

1.7-2.0

2.0

g/lb

0.7-0.9

0.9

Mixed sport

g/kg

2.5-3

3

g/lb

1.1-1.4

1.4

Although protein quantity would appear to be more important than quality, protein intake is certainly not the whole picture with regards to optimising body composition or performance. To finish off nicely, I’ll leave you with a final quote by Tipton and Wolfe:

“Current literature suggests that it may be too simplistic to rely on recommendations of a particular amount of protein per day. Acute studies suggest that for any given amount of protein, the metabolic response is dependent on other factors, including the timing of ingestion in relation to exercise and/or other nutrients, the composition of ingested amino acids and the type of protein”