It seems like you can't open a cycling magazine, read a running forum or speak to an endurance enthusiast without being drawn into a discussion about beetroot juice. With article headlines such as, “Power to the beetroot - PB up, BP down” and “Beetroot Juice: The Drink of Champions” becoming evermore common, I thought it would be a good time to take a look at some of the research and determine whether these claims are justified. As such, the aim of this article is to discuss all things beetroot and try to find out if it really is “The Drink of Champions”.Read More
Just when I thought I was done with the BCAA series after exhausting the scientific literature, I came across some more research that put a spanner in the works. Many of you reading this know I’m not a fan of Poliquin in general, but if he turns out to be right and I’m wrong, I’m willing to change by position, as that is what every good scientist should do. As far as I’m concerned, I’m not interested in being right, but having the right answers. So if I am wrong, I consider it a learning opportunity.
What is this research?
The research in question is two papers by Bul & Chitè published in an obscure Soviet (now known as Russia) journal in 1941 and 1942, respectively. The reason I missed this research during the time of writing my initial articles, is due to the fact that they can’t be accessed online, and therefore can’t be linked to, unfortunately. However, I was lucky enough to receive an email last week from a subscriber to my blog who kindly emailed me the two articles in full. Since they can’t be accessed online, I’d be happy to send them to whoever wants them, just drop me an email.
What was found?
Because the papers were published in a Soviet journal, they were written in Russian. Luckily, one of these papers (the 1942 one) has been translated to English so I can only comment on the details of that particular study. In it, Bul & Chitè compared the effects of a BCAA-saline solution (0.2g/kg/h) with a placebo (saline solution), delivered intravenously every hour, for four hours, following a series of intense training drills, on measures of body composition and performance in a cohort of Soviet Special Operatives. Given the invasion of the Soviet Union in 1941 by the Germans, this type of study seems rather timely. After the 12-week trial, the authors observed an increase in muscle mass of 6.3kg and decrease in fat mass of 1.7kg in the experimental group, compared to values of 0.9 and 0.6kg, respectively, in the placebo-control group. To top things off, the experimental group gained an average of 28kg on their back squat and 37kg on their deadlifts, compared to 6 and 8kg, respectively, in the control group. Though I’ve highlighted limitations of such studies before, what makes this study unique is that subjects were consuming a maintenance calorie diet with already sufficient amounts of protein (2.6g/kg of protein). This is significantly more protein that that observed in other investigations, making things very interesting indeed!
Though this study is limited by the method of BCAA delivery (infusion vs. oral ingestion), as BCAA are rapidly digested and appear in the blood stream soon after ingestion, oral ingestion probably would’ve produced similar results. As such, if we take a 75kg individual as an example, it would be the equivalent of ingesting 15g of BCAAs straight after a workout, and an additional 15g every hour, for the next three hours (60g total). Coincidentally, this arrives at a value remarkably similar to that advised by Poliquin. Is this a fluke on Poliquin’s part? Nobody knows, and I’ve never heard of him speak of this research. It would seem however, that with his years of experience in the field, he is able to notice subtle trends regarding the efficacy of various supplementation protocols, which future research would be needed to verify. Because of this, it begs the question: if Poliquin might be right about the BCAAs, what else might he be right about?
Though the authors of the study were unable to explain the mechanism behind their findings, based on advances in the understanding of protein metabolism in the past decade, there seems to be some plausible explanations. Firstly, as BCAAs aren’t bound to the matrix of a whole food protein source, they are rapidly absorbed and create a huge spike in levels of leucine in the blood. During normal situations (i.e. between-meal doing of 6g BCAA as advised by Layne Norton) levels of plasma leucine would quickly return to baseline. However, with the aforementioned higher doses, supraphysiological levels of plasma leuince concentration would be extended for a much longer duration, resulting in a much higher rate of MPS, thus leading to greater muscle growth over time. This is something that is not achievable with a normal protein source given its relatively slower rate of digestion.
Other lines of evidence supporting these findings
The knowledge that the Soviets possessed regarding the effects of mega-dosing BCAAs may have translates to other uses, most notably, their domination of the summer Olympic games following WWII. The Olympics were suspended in 1940 and 1944 due to the war, and the Soviet Union didn’t compete in the 1948 games. However, from 1952-2000 (with the exception of 1984 when the Soviet Union boycotted the Los Angeles games), the Soviet Union/Russia have either placed 1st (1956, 1960, 1972, 1976, 1980, 1984, 1988 & 1992) or 2nd (1952, 1964, 1968, 1996 & 2000) in the medal table; that includes topping the medals table in six consecutive games!
Though anabolic steroids certainly played a large part of their success, virtually every developed country would have had access to the same drugs, nullifying any potential advantage to be gained from them. As such, it may well have been the inside knowledge of the benefits of BCAAs that were responsible for their Olympic domination.
Further support comes in the form of BCAA supplements. The popularity of BCAAs as a supplement didn’t really being until the early 2000s, so by the time the Athens games were held in 2004 (when athletes from all countries were using them), Russia didn’t have the advantage of BCAA supplementation. So what happened in Athens? Well, Russia placed below 2nd for the first time in over half a century; this can hardly be written off as coincidence.
Having only been aware of these studies for the past week or so, I though I’d implement BCAA mega-dosing in my current diet and training setup. Though I’ve only been using a protocol that I devised based on the above findings (20g immediately before, 20g during and 20g immediately after training) for just a week (four sessions in total), I’ve already put 25kg on my deadlift and 15kg on my squat. I’ve also gained 2kg in weight with no change in skinfold thickness, indicating it is pretty much all from muscle. For the record, my diet has remained exactly the same, ruling out the possibility of dietary influences.
Additionally, by scouring the fitness/nutrition online forums, I began to notice a trend, in that people who take upwards of 40g BCAA per day seem to benefit in the presence of already sufficient protein. Those who consume more modest amounts tend not to experience such ‘steroid-like’ gains in strength and size unless their protein is lacking.
As a final piece of evidence supporting the validity of the above study, Charles Poliquin and Nick Mitchell (dubbed by Men’s Fitness as “one of the world’s leading body composition experts” and by Time Out as “London’s best personal trainer”) – who both advocate high doses of BCAAs – are very well muscled, as well as having got their clients results following such protocols. One day, with continued use of BCAAs, I'll hopefully reach a similar size as these guys.
In summary, if you believed a word of what was said in this post then April fools’! If not, then I wasn’t subtle enough (maybe next time). For those that were fooled by the article, it is an important demonstration of how logical sounding arguments can be taken as fact. To give you an idea of how to spot such deceptions in other work, what follows is a list of common logical fallacies that I deliberately committed in order to strengthen my fabricated position:
- I made up research – this one is common, always look out for references linked to PubMed.
- I appealed to coincidence – there are numerous explanations for the success of the Soviets during the summer Olympics.
- I appealed to authority – I backed up this fictitious study with Poliquin’s practise. Since he is held in high esteem (I’m not sure why), people are more likely to believe it. I also put Nick Mitchell’s name in there too for a laugh. Speaking of Mitchell, credentials like “London’s best personal trainer” are at best, comical, and at worst, meaningless.
- I appealed to popularity – stating that everyone on message boards gets results make it seem like it is really popular and really works. Everyone is convinced when “real” people get results, right? (As if humans in controlled trials aren’t “real people”).
- I appealed to personal observation and experience. It must be remembered that the placebo effect is extremely powerful, and if I know what I’m taking, the self-experiment is flawed from the very start due to an expectation bias. Not to mention completely ignoring all the research highlighted in parts 1-3 of my BCAA series.
- In using my personal experience, I also appealed to aesthetics. Saying I got bigger by doing something, or that BCAAs must work because Poloquin and Mitchell use them suggests that only BCAAs are responsible for their physiques as opposed to other 'special supplements'.
- Finally, I also made up physiology in the part about extending supraphysiological rates of MPS and provided no scientific references to support such claims, just links to less than scientific sites such as cutandjacked.com, mensfitness.com and charlespoloquin.com.
‘Neurotransmitter’ appears to be the buzz word of the moment; the belief being that nutrition can have a significant affect on the appearance of blood and brain neurotransmitters themselves, a substantial body of evidence supports this notion (Wurtman & Fernstrom, 1974; Growdon & Wurtman, 1977, 1980; Gelenberg, Wojcik & Growdon, 1980). Such evidence has given rise to a spate of theories, generally all of the ‘Broscience’ ilk, a number of which originate from Charles Poliquin’s ideologies. The Meat & Nut breakfast is his most infamous nutrition and neurotransmission tale. While I personally also see the benefits of the inclusion of meat and nuts at breakfast, Poliquin has vastly over exaggerated the impact this meal has on your brain neurotransmitters and thus the subsequent actions and emotions. Here we’ll critique the current evidence regarding nutrition and neurotransmission and hopefully dispel any of the Poliquin myths along the way.
Science talk, a neurotransmitter is a chemical signal which allows transmission of signals from one neuron to another, across a synapse; in English that basically means it’s a vehicle which allows messages to be transported from one nerve to another. Neurotransmissions allow, and control muscle fibre contraction, bodily actions, emotions and feelings. The most significant neurotransmitters in the human body are acetylcholine, norepinepherine, dopamine, GABA, glutamate, serotonin and endorphin.
Neurotransmitters and cognitive function
Serotonin is a known sleep inducing agent (Hartman & Spinweber, 1979), and human research has suggested serotonin reduces subjective alertness, objective performance, and increases feelings of relaxation and lethargy (Spring, 1984). Dopamine on the other hand is associated with pleasurable reward, behaviour, cognition, mood, memory, movement, attention and learning. Acetylcholine has a number of physiological functions, and is a widely distributed excitatory neurotransmitter that in the central nervous system is involved in wakefulness, attentiveness and memory. Interestingly, Alzheimers disease is characterised by a significant reduction in acetylcholine concentration and function (Francis, 2005), highlighting its importance in human performance.
Neurotransmitters and nutrition
The primary neurotransmitters are synthesized from the amino acids, tyrosine and tryptophan. The rates at which these neurotransmitters are synthesized depends upon the availability of the amino acid precursor; where tryptophan is the precursor of serotonin, and tyrosine is the precursor of dopamine and norepinepherine (Wurtman et al. 1980); this link was made in the 70’s and early 80’s when evidence from rat studies became available. The administration of a single dose of tryptophan elevated brain tryptophan levels, and thus the levels of serotonin and its major metabolite 5-hydroxyindole acetic acid (5-HTP). The administration of tyrosine similarly elevated brain tyrosine levels, and thus catecholamine synthesis increased in the central nervous system (CNS), while the consumption of lecithin or choline (found in fat) increases brain choline levels and neuronal acetylcholine synthesis (Wurtman & Fernstrom, 1975).
Most of these studies were on rats, using a single dose of the precursor, although similar effects have been seen following the consumption of dietary sources. The consumption of a single protein-free high-carbohydrate meal elevated brain tryptophan levels. Similarly the consumption of a single 40% protein meal accelerated brain catecholamine synthesis through increased availability of tyrosine (Wurtman & Fernstrom, 1975). A minimal change of delta 0.07 in the tryptophan to large neutral amino acid ratio is required to influence mood following protein consumption, so a considerable shift in the ratio is required to have an effect on subsequent cognition (Fernstrom, 1994).
These early observations clearly demonstrate that serotonin and catecholamine neurotransmitters are under specific dietary control, so in that regards Poliquin is correct. The acute effects of a high-carbohydrate protein-free meal, typical of most children’s and a vast majority of westerner societies breakfast (think cereals) do induce marked increases in serotonin synthesis, and thus may result in increased feelings of lethargy; however, is the absolute avoidance of carbohydrate justifiable based on the current evidence?
It appears not. Interestingly, the addition of protein to that otherwise protein-free high-carbohydrate meal suppressed the increases in brain tryptophan and serotonin (Wurtman & Fernstrom, 1975), because protein contributes to the blood plasma considerably larger amounts of the other neutral amino acids (e.g., BCAA’s, phenylalanine) than of tryptophan. Tryptophan and other large neutral amino acids, most notably the BCAA’s leucine, isoleucine and valine share and compete for uptake along the specific transport mechanism across the blood brain barrier (Maughan, 2000). Therefore brain 5-HTP synthesis will increase when there is an increase in the ratio of free tryptophan to BCAA’s in the blood (Chaouloff et al. 1986), thus explaining why the addition of protein to an otherwise protein-free high-carbohydrate meal can suppress serotonin synthesis.
Just to confirm, this theory has also been confirmed in humans. Using 20 men, Lieberman et al. (1985) administered single oral doses of tryptophan (50 mg/kg) and tyrosine (100 mg/kg) in a double-blind, crossover study. Tryptophan increased subjective fatigue and decreased self-ratings of vigour and alertness, but did not impair performance on any of the tests. Tyrosine produced no effects in our young population compared with placebo, but did decrease reaction time relative to tryptophan. The authors concluded that tryptophan has significant sedative-like properties, but unlike other sedatives may not impair performance in a series of cognitive tests. Now being critical, it’s extremely unlikely – probably impossible in fact – you’d ever consume 50 mg/kg tryptophan in a single dose from a dietary source, thus wouldn’t necessarily have to worry about the negative mental effects of tryptophan consumption.
So Poliquin, who strongly advocates the avoidance of carbohydrate at breakfast time has no science to back up such claims. The truth is the brain neurotransmitters are influenced by the ratio of free tryptophan to large neutral BCAA’s (Fischer et al. 2002), so a mixed meal that will maintain a balance in that ratio is adequate. Further an increase in the ratio of free tryptophan to large neutral amino acids following a high-carbohydrate meal is reversible through the addition of a protein to that meal.
An intricate study by Fischer et al. (2002) examined the cognitive effects of isoenergetic meals consisting of three carbohydrate ratios, a carbohydrate rich meal (4:1), a balanced meal (1:1), and a protein rich meal (1:4) in 15 healthy subjects. Not surprising, attention and decision times were improved in the first hour with the high carbohydrate meal, owing to the greater rise in glucose metabolism. But during the first hour it was both the balanced and higher protein meals that resulted in improved performance. Further, overall reaction times in a central task were fastest after the balanced or high protein meal, thus suggesting a high protein meal or a balanced meal seems to result in better overall cognitive performance. Although the results also revealed participants subjective measures of ‘tasty’ and ‘pleasant’ were greater in the balanced meal than in the high protein meal, which suggests this would be the most effective in a practical sense.
Now, from reading the above it may appear that carbohydrates contain significant amounts of tryptophan, thus increase free tryptophan concentrations after ingestion, thus increasing tryptophan uptake and stimulating serotonin synthesis. However, this is not the case. For the sake of dispelling Poliquins breakfast argument let’s take oats for example, the amino acid profile of 100g oats indicates a tryptophan concentration of 234 mg, compared to 694 mg isoleucine, 1284 mg leucine, and 937 mg valine, which collectively make up the BCAA’s. So a high carbohydrate breakfast doesn’t contain that much tryptophan and yet accelerates serotonin synthesis through an increase in tryptophan uptake by the brain, how does that work?
Although the carbohydrate meal itself doesn’t contain much tryptophan, the insulin that is secreted following the carbohydrate meal results in a decrease in plasma levels of the large neutral amino acids (tyrosine, phenylalanine, BCAA’s and methionine) that would ordinarily compete with tryptophan for uptake by the brain. Tryptophan then crosses the blood-brain barrier and is converted to serotonin (Spring, 1984).
So it’s not actually the carbohydrate that causes the problem, it’s the insulin response to that carbohydrate that is the issue.
The following is a novel thought that stemmed from logic and my intuition: looking at the insulin index created by Holt et al. (1997) beef, the food advocated by Poliquin in his infamous meat and nut breakfast comes in at an insulin area under the curve of 7910 ± 2193 pmol.min.L and grain bread, a food demonized by Poliquin in fear of it frying your brain cells comes in at 6659 ± 837 pmol.min.L. The insulin index clearly indicates beef is more insulinogenic than most forms of carbohydrate, therefore suggesting that the net effect in regards neurotransmitter synthesis of a high-protein carbohydrate-free meal may be similar to that of a mixed meal. The greater insulin response to beef consumption will lead to a reduction in the BCAA’s and other neutral amino acids, leaving free tryptophan to be taken up by the brain; interestingly 100g steak contains more tryptophan than the same portion of oats (288 mg).
Logic and intuition suggests this could be true, although a number of rat studies have disproved the hypothesis, where Rouch et al. (1998) revealed a high protein diet significantly reduced serotonin concentrations for 2-hours, Wurtman & Fernstrom (1975) reported similar findings. Interestingly, the reduction in serotonin following protein feeding is thought to be among the reasons why protein is more satiating that carbohydrate.
Finally, Poliquins suggestion that the first meal of the day dictates that whole days brain neurotransmitters. We’ll start with a rat study from 1995; Fernstrom & Fernstrom studied the brain tryptophan concentrations and serotonin synthesis rates of fasted rats fed a high-carbohydrate meal followed 2-hours later by a protein-containing meal. They demonstrated that when the high-carbohydrate meal was fed first, brain tryptophan concentrations increased as did serotonin synthesis, and these changes were reversed at 4-hours if the second meal contained protein. Interestingly they go on to conclude, and I quote: “brain tryptophan concentrations and serotonin synthesis are thus responsive to the sequential ingestion of protein and carbohydrate meals if there is a sufficient interval between meals”. Similarly, Rouch et al. (2003) reported the plasma ratio of free tryptophan to large neutral amino acids was increased by a carbohydrate meal, and remained high for 2-hours, a subsequent casein (protein) meal reversed this change. Interestingly, a first casein meal reduced the ratio, and was not increased again by a subsequent carbohydrate meal. These findings actually favour Poliquins suggestions, although the weight of the evidence doesn’t, again supporting my belief of a mixed meal consumption.
From a human perspective the reversible nature of neurotransmitter synthesis is supported by the central fatigue hypothesis, which predicts that the ingestion of BCAA’s during exercise will raise plasma BCAA concentration and hence reduce transport of free tryptophan into the brain; subsequently reducing the formation of serotonin and alleviating sensations of fatigue and therefore improve endurance performance (Gleeson et al. 2005). This hypothesis lacks support, although does highlight the obvious reversible nature of neurotransmitter synthesis.
Conclusion and recommendations
My recommendation based on this evidence is that a single macronutrient meal can have a significant impact on the brain neurotransmitters, where a protein-free high-carbohydrate meal can increase serotonin synthesis, and thus increase feelings of fatigue just as Poliquin suggests. Although alternatively, a high-protein high-fat carbohydrate-free meal can increase catecholamine synthesis. Granted you would favour catecholamine synthesis, but with your daily macronutrient requirements in mind, combined with the fact that eating single macronutrient meals would be extremely tasteless and boring it would be more appropriate to consume mixed meals than to focus on meals free from certain macronutrients in fear of a surge of sleep inducing neurotransmitters.
In conclusion the promotion of carbohydrate free, high-protein breakfasts is largely unsubstantiated. A mixed meal consisting of meat, carbohydrate (both starchy and fibrous) and fat (possibly nuts) is adequate, and in a practical sense is optimal.
Chaouloff et al. (1986) http://www.ncbi.nlm.nih.gov/pubmed/3083049
Fernstrom & Fernstrom (1995) http://ajcn.nutrition.org/content/61/2/312.short
Fernstrom et al. (1994) http://www.ncbi.nlm.nih.gov/pubmed/7903674
Fischer et al. (2002) http://www.ncbi.nlm.nih.gov/pubmed/11897269
Francis (2005) http://europepmc.org/abstract/MED/16273023
Gelenberg et al. (1980) http://www.ncbi.nlm.nih.gov/pubmed/6443584
Gleeson et al. (2005) http://jn.nutrition.org/content/135/6/1591S.abstract
Growdon & Wurtman (1977) http://www.ncbi.nlm.nih.gov/pubmed/14577
Hartman & Spinweber (1979) http://www.ncbi.nlm.nih.gov/pubmed/469515
Holt et al. (1997) http://ajcn.nutrition.org/content/66/5/1264.full.pdf
Lieberman et al. (1985) http://ajcn.nutrition.org/content/42/2/366.full.pdf
Rouch et al. (1998) http://www.sciencedirect.com/science/article/pii/S0031938498002042
Rouch et al. (2003) http://www.ncbi.nlm.nih.gov/pubmed/12722987
Spring et al. (1984) http://www.ncbi.nlm.nih.gov/pubmed/6400041
Wurtman, R., & Fernstrom, J. (1974). Nutrition and the Brain. Scientific American, 230, 84- 91.
Wurtman & Fernstrom (1975) http://ajcn.nutrition.org/content/28/6/638.abstract
Wurtman et al. (1980) http://www.ncbi.nlm.nih.gov/pubmed/6115400
Bio: Matt holds a BSc (Honours) degree in Sport & Exercise Science, an MSc in Nutrition Science. Through his own Performance Nutrition business, Nutrition Condition, he delivers frequent Health & Wellbeing Workshops to corporate and personal clients advising on how best to develop a sound, scientifically structured nutrition programme free from fads and marketing bias. Nutrition Condition also delivers Performance Nutrition services to professional athletes.
For regular updates follow Matt on Twitter @mattNCUK.
Continued from part I
2. Setting protein intake
With the more complicated stuff out of the way, the next step of filling the calories with the macronutrients is really simple.
I discussed the issue of protein requirements here so I won’t go into any great detail in this article. The RDA for protein is set at 0.8 grams per kilogram of bodyweight (g/kgBW), while research typically recommends intakes of 1.2-2.2 g/kgBW for athletic populations (i.e. from endurance to strength athletes). As I mentioned in the protein requirements article, I tend to err on the side of too much than too little protein and typically recommend intakes between 1.7-3 g/kg.BW for most individuals. Such intakes are realistically achievable by most and wouldn’t seem to impede on carbohydrate requirements of athletes for a given energy budget.
3. Setting fat intake
Unlike protein there isn’t really an evidenced-based dosing range to cite when talking about fat intake. As long as essential fatty acid intake is met, which is virtually impossible not to with a typical diet, fat intake technically doesn’t have to be any higher. Having said that, calories have to come from somewhere. Furthermore, in order for a diet not to be bland, in addition to there being enough fat to optimise the absorption of fat soluble vitamins, I like to use intakes of 1-1.5 g/kg as a starting point, which suit both non-athletes and athletes (due to the contribution of intramuscular triglycerides [IMTG] as a fuel source during exercise) alike.
4. Setting carbohydrate intake
Now that we’ve set total kcal, protein and fat, carbohydrates simply fill the remaining calorie allotment. Using myself again as an example, I’ll run through steps 1-4 based on my stats and training/activity.
- REE/BMR = 24.2 x 78 kg = 1888 kcal. Since the “moderately active” activity factor most accurately represents my current activity I’ll multiply my REE/BMR by 1.55 (1888 x 1.55) giving a TEE of 2925 kcal per day.
- Since my athletic goals include maximising muscle hypertrophy and strength, I’ll set protein intake at the upper end (3g/kg of BW) of my recommendations. This equates to a daily protein intake of (78 x 3) 234g. As each gram of protein contains roughly 4 kcal, daily protein intake equates to 936 kcal.
- As I don’t deplete a great deal of IMTG through training, I’ll set fat intake at the lower end of my recommendation (1g/kg). This equates to a daily fat intake of (78 x 1) 78 g. As each gram of fat contains roughly 9 kcal, daily fat intake equates to 702 kcal.
- To calculate carbohydrate intake in grams, all we need to do is subtract the sum of protein and fat kcal from total kcal, then divide by 4 (the amount of kcal per gram of carbohydrate).
- Protein = 234 x 4 kcal/g = 936 kcal
- Fat = 78 x 9 kcal/g = 702 kcal
- TEE (2925 kcal) – 1638 (936 + 702) = 1287 kcal from carbohydrate.
- 1287 / 4 (number of kcal per gram of carbohydrate) = 321 g
Energy: 2925 kcal
Protein: 236 g (32%)
Fat: 78 g (24%)
Carbs: 321 g (44%)
This whole process is pretty straightforward and should take a few minutes at most since all you need to know is your current body weight and training volume/frequency.
From the totals, you will also notice I listed the percentage of total energy that each macronutrient makes up. While knowing this percentage breakdown isn’t all that useful for most purposes, it gives you an idea of how your diet compares to ones that are set up as percentages. In reality, these percentages are not too dissimilar from the Zone Diet. However this won’t be the case for everyone as made in the earlier example.
As a final point on this matter, diet percentages are secondary to meeting a person’s individual macronutrient requirements. In other words, once you’ve worked out how much protein and fat you require, allow carbs fill the remaining calorie budget and let the percentages be what they are. Attempting to do things the other way round is confusing and doesn’t address individual needs.
From the current example, my real-world experience tells me that my maintenance energy need has been overestimated by roughly 200-300 kcal. In this case, I’d leave protein and fat intake the same and decrease the suggested carbohydrate intake from 321 g to roughly 246-271 g per day.
From there, you would split the macronutrients up over a realistic number of meals (3-5) over the course of the day and aim to meet these individual macronutrient goals. It is worth remembering that the total macronutrients consumed is far more important (at least in terms of body composition) than the macronutrient subtype (i.e. type of protein, type of fat, glycaemic index etc.), meal frequency, or any specific timing of the ingested nutrients etc. (with the possible exception of outlandish extremes that are very rarely encountered in the real-world).
Is this for everyone?
As with everything in relation to nutrition, the answer is almost always, “it depends”. These values aren’t set in stone I just use them as a good staring point. I don’t mind going lower than the bottom end of my protein recommendations (e.g. for people who already have achieved their desired amount of lean body mass and are eating at maintenance). However, rarely do I suggest much more than 3 g/kg, even when dieting (a possible exception being drug-fuelled bodybuilders). After accounting for protein, I typically let fat intake determine carbohydrate intake (as it makes up the remaining calories). However, for type II diabetics or insulin resistant individuals, or just people who don’t tolerate carbs very well in general, I like to opt for a lower carbohydrate intake. Because of this, fat intake has to increase in order to make up the calories.
For people who don’t really engage in a great deal of high-intensity exercise, fat intake can also be set a bit higher than recommended above (if preferred), with a relatively lower carbohydrate intake. Contrary to what the insulin-phobic “gurus” would like to convince you, calories do count, and after adequate protein is set, skewing fat or carbohydrate either way will have little overall impact on body composition in healthy individuals as long as total calories remain the same. Anyone who says that you can eat as much as you want as long as you avoid carbs has either completely ignored the available evidence on the matter or/and is trying to sell something.
What about fat loss or muscle gain?
While these recommendations are fine for people who wish to remain weight stable, most people want to lose weight (fat), and some, gain weight (usually muscle). In the case of losing body fat (speaking exclusively about manipulating diet), I like to increase protein slightly (relative to maintenance levels; see my previous article on protein requirements for details on this) and then create an energy deficit as a percentage of maintenance requirements (by roughly 10-20% as a starting point). The reason being that an often quoted 500 kcal deficit would be quite significant for a small female with a maintenance caloric requirement of 1800 kcal (28%), and less so for a large male with a maintenance requirement of 3500 kcal (14%). Calories would be cut from either fat, carbs or both and would depend on several factors (e.g. level of hunger, type of training, food preference etc.). It should also be mentioned that individuals might wish to eat the same and just increase activity, or use a combination of both dieting and increased exercise to bring about fat loss.
In terms of gaining muscle mass, I’d go with the exact opposite (i.e. increase carbs and/or fat) except for keeping protein the same as maintenance levels. Though these recommendations aren't a bad starting point, I should point out that I am grossly oversimplifying matters, and to go in any great detail would take many more articles.
Though total macronutrient intake would seem to have the greatest overall impact compared with any single dietary modification, other variables such as: nutrient timing, meal frequency, macronutrient subtype, nutrient density (vitamin and mineral content per calorie), non-nutritive dietary components and supplementation, would have a measureable impact on body composition, sporting performance and health. That is assuming the ability of an individual to successfully implement a desired macronutrient intake on a daily basis in the first place.
Summary & application
Hopefully these two articles have shed some light on how to properly construct the backbone of a diet (i.e. the macronutrient content) in a simple and individualised manner. Estimating total maintenance macronutrient intake is briefly summarised below and requires knowledge of only current body weight and training load:
- Multiply bodyweight (in kg) by 24.2 (males) or 22 (females) to determine resting energy expenditure.
- Multiply this value by an appropriate activity factor.
- Set protein intake between 1.7-3 g kg of bodyweight.
- Set fat intake between 1-1.5 g kg of bodyweight.
- Let carbohydrate fill the remaining calorie budget.
This totals would then be roughly divided among a realistic number of meals and modified in accordance with real world observations (i.e. changes in body composition) or body composition goals (e.g. fat loss or muscle gain).
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.
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.
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.
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.
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”