Dr Phillips,
I appreciate you taking the time to construct an amazingly
thorough and fair response to what can be, at times, a volatile
debate - especially when it's done behind the relative anonymity
of an email exchange. Your respectful demeanor is just what these
types of exchanges need in order to stay on track and really
make a meaningful contribution. Your response can teach a great
lesson to all those "listening in" as many are younger
students who will be entering this field and will have many opportunities
to debate in the future. Sometimes these debates, especially
when done on the web, can degrade rapidly to slanderous mamma-slam
fests. Hopefully, when faced with "opponents" who wish
to take things to that level, those reading this exchange can
follow your example, sticking to the facts and debating in a
reasonable and rational way. That said, let's roll up our sleeves
and get down to the business at hand - discussing protein intake
(and, since it's really difficult to discuss one macronutrient
in isolation of the others, especially when our end is applied
nutrition, we should probably touch on overall dietary strategy
a bit also).
To begin with, though, I need to bring up a side issue that
should be clarified before moving on. The "Protein Prejudice"
article that was referenced in your response (printed in full
below) was actually published back in March of 2003, nearly 2
years ago. Why make this point? Well, in the 2 years that have
passed since the publication of this article, certainly new data
have emerged that warrant discussion (some of which you referenced
in your letter yet I was not privy to at the time that the article
was written).
This, I think, brings up a very important lesson for all of
those reading this exchange. Many reading this are very interested
in the applied side of this field and may want to publish articles
in print or electronic formats (and some may already be doing
so). Here is a caution directed at them, if I may...publish something
on the web today and regardless of how you feel about what you
wrote 10 years from now, you'll have to live with it.
Now, in this specific case - the Protein Prejudice article,
I don't regret anything I've written and I still stand behind
my comments 2 years later (rationale below). But there can certainly
be cases where one might have a problem with the finality of
a web publication.
Here's an example, looking back to Dr Phillips' flat world
analogy. Imagine that today's best scientists believe that the
world is flat. Imagine further that you're an expert map-maker
and you publish (on the web) a map of this version of the world.
What happens when, 10 years later, it's proven that the world
is round? Since that flat map doesn't disappear, it's there for
the eternity of the web - with your name on it. Of course, you're
cutting edge and publish round earth maps as soon as you can.
But, one day, someone surfing the web will find your flat world
map and, well, you'll immediately be ranked right up there with
the people who believe crop circles were created by alien visitors
and those who search out Bigfoot. So take note - the web is a
great way to quickly disseminate info. But what you put out there
might come back to bite you one day. So choose your words carefully!
Ok, that digression aside, one more note with respect to the
original Protein Prejudice article. This was published on a web
site targeted to lay readers without the scientific training
we have and are more interested in, if you will, applied nutrition.
As a result, the article was not intended to be an exhaustive
review of the literature. Therefore comparing one of your more
recent well-written literature reviews to one of my (albeit well
written, if I do say so myself :-) short, 2 year old, lay articles
isn't exactly an apples to apples comparison. So I'm glad we're
getting this chance to speak directly!
Now, let's get down to your comments. It should come as no
surprise to anyone who's read many of my articles or my books
(Scrawny to Brawny and Gourmet Nutrition) that I am in full agreement
with nearly everything Dr Phillips has commented on - especially
with his well referenced comments (fully cited, I might add!).
Therefore, for the blood thirsty, you won't get your blood here.
However, I do believe that while some of the scientific interpretations
of the muscle literature may be similar, there are a few outstanding
issues that demand discussion. I'll address them below. (Dr Phillips'
statements in bold, my responses below them and indented):
I have read Dr. Berardi's paper and have found it generally
sound, but lacking in sufficient evidence to truly be considered
'truth' in some areas…
I agree...in fact much of my "lay" writing is more
speculative than most scientists would feel comfortable with.
If I were writing a literature review, certainly, there would
be leaps that I simply couldn't and wouldn't take. But in this
type of forum, where I am writing to an "applied" crowd,
I feel that I do have free rein to take the literature that is
available and make a few "speculative leaps" at some
things beyond what the literature tells us explicitly. In this
sense, without the ability of science to demonstrate verisimilitude,
my speculations are just that - my best guesses based on what
we do know in the literature AND what I see in practice.
(Forgive the impending "philosophy of science" tangent
here but in addition to my physiology undergrad work, I did study
philosophy and loved the study of the philosophy of science).
Any scientist worth his or her own salt would agree that we're
barely scratching the surface of what's yet to be known, explored,
and discovered. Yet we still have to make decisions, every day,
based on incomplete evidence. And that's where much of my writing
leads me. I look to the scientific literature but since, in parallel
to my scientific training, I've run a successful coaching/consulting
practice - one in which I attempt to rigorously control what's
possible to be controlled in free living athletes/clients and
document what I see, I also look to the "clinical"
(for lack of better word) results that I see every day. Finding
this balance is difficult but that's my mission and the express
mission of my company - Science Link, Translating Research Into
Results. Our tag line is this: However Beautiful the Strategy,
You Should Occasionally Look at the Results. By striving (and
I certainly may miss this mark from time to time) to find the
balance between research and results, applied and basic, clinical
and laboratory, I know that I can find support for ideas that
work and drive new ideas in the process. This is what I get excited
about!
Of course, it's critical to be true to the rigorous data we
have got:
"Science is merely an extremely powerful method of windowing
what's true from what feels good; without the error-correcting
machinery of science we are lost to our subjectivity..."
But science alone doesn't always get it right - nor is it
always there with an easy answer to "what's true" -
nor is it capable of supporting or refuting many, many hypotheses
that we continually test (n=1 of course) in our own daily lives.
So it's my impression that the dialogue between "clinical"
and "laboratory" observations is critical in making
recommendations/decision for daily life (including nutrition
and exercise research).
Heck, this is why I wanted to open up this conversation…Dr
Phillips might be one of the smartest guys around in our field
and his input on this question is invaluable. I think I'm a pretty
smart cookie too. And there are lots of really intelligent people
reading this. What a cool chance to really break new ground,
get a bunch of new ideas stimulated, and open up a running dialogue
that blends "clinical" and "laboratory."
So even if my article isn't true in the scientifically verifiable
sense of the word true, I'm just happy that it might stimulate
enough discussion so that we can better get after the "truth".
Hence, trying to talk about a requirement or even optimizing
protein intake based on finding from nitrogen balance studies
is like trying to circumnavigate the globe using a map before
we knew the earth wasn't flat - the instrument is badly flawed
so it will lead you, ultimately, in the wrong direction.
This is a fantastic analogy and that's why I added it here
again (after mention of it above), a bit out of order. I agree
that the N balance studies are flawed - but, unfortunately, until
you start publishing your more recent data, Dr Phillips, they
represent the bulk of what's out there and available for review
(especially 2 years ago when I wrote the article). This area
is so poorly researched and, as we both know, that's due to a
lack of governmental funding for areas such as this one - one
that's more recreational than of major public health concern
(although, of course, there are public health applications to
this type of work).
So think of us as miners with small head lamps in a dark cavern
that's not been well explored. We can make guesses as to what's
ahead of us in the cavern. And these guesses are based on the
small amount of light we can see with and the small amount that
we're seeing (of course, limited to the area of the cavern we're
standing right now).
So I remain open to the suggestion that one day someone will
find a way to rip the roof off that cavern and I might feel very,
very silly about my guesses when it's exposed in its entirety.
But I don't believe that I can be faulted for reporting on what
I see, what I guess, and how I interpret both.
(Not an excuse for error, just a belief system and way of
looking at what I do.)
Also, data from Mike Rennie's Lab (Bohe et al. J. Physiol.
532: 575-579, 2001) shows the in the face of available amino
acids that muscle protein synthesis is turned off after 1-2h.
Now, although very interesting, these data aren't a good justification
for a lower protein requirement/optimization point. In fact,
I distinctly remember bringing these data up at ACSM (was it
last year?) at a session Dr Phillips was moderating. And I believe
the consensus was that it would be nearly impossible to duplicate
(with the diet) the "steady rate" amino acid infusion
program of this study.
In essence, when you eat protein you get peaks and troughs
and it's probably the change in amino acid concentrations that
stimulate the protein synthetic mechanisms - not a threshold.
Now, Rennie's more current data may suggest otherwise - I
can't wait to read it in print. But as of our last conversation,
it was Dr Phillips' opinion that amino acid changes in the blood
are what govern synthesis - not having an amino acid concentration
above a certain threshold. This means that each time we eat more
protein we'd get a bump in PS. So I don't really see how this
comment is relevant - interesting, yes - relevant, I'm not sure.
Let's say a hypothetical individual - Fred - weighs 90kg
and in one year gains 10kg (22lb) of muscle, not mass, muscle.
That's a pretty impressive rate of gain and something most of
us would be happy with?
Now, that means over a year Fred has gained 10kg of muscle,
which is 75% water, so really he has gained 2.5kg of muscle or
protein (i.e., 2500g). That means he has gained: 2500g protein
/ 90kg / 365d or ~ 0.076 g protein/kg/d
Now if we assume that the RDA is sufficient to cover ALL
of Fred's other protein needs, which is likely a large overestimate,
then what Fred would require to east on a daily basis is:
0.8 g protein/kg/d + 0.076 = 0.876 g protein/kg/d to gain
22lb of muscle
Woah, hold on you say it takes 6 times as much protein
consumption to lay down the equivalent amount of muscle (estimate
from Mr. Colgan and the 'Colgan Institute' - hotbed of muscle
research). In truth I am never sure where this number comes from
since literature from the animal science area indicates that
to lay down protein at rates sufficient to support weight gain
in a growing steer - who in 180d will lay down 226kg of mass
of which 60% is protein you need only consume the mass gained
x 2 in terms of protein content, but lets say it's 6. OK, so
now you need to consume:
0.8 g protein/kg/d + 0.456 g protein/kg/d = 1.256 g protein/kg/d
to gain 22lb of muscle
Of course, these are all guesses - but the point is well taken.
However, just how meaningful are they? Probably about the same
as suggesting that burning an extra 20kcal/day by gardening would
lead to an increase in monthly caloric expenditure by 600kcal
and in yearly expenditure by 6000kcal. This surely means the
person would lose just short of 2 lbs per year from gardening
for 3 minutes a day!
Forgive the absurd example but the point is that the body
makes constant adjustments, adjustments designed at the maintenance
of homeostasis in the face of such subtle perturbations. As a
result with all the "slop" room in the calculation
above, it's really hard to say what exact amount of "extra"
protein is needed to pack on more muscle mass. I do "get"
your point that according to even very liberal assumptions, it
doesn't seem like much and perhaps athletes don't need much more
protein for enhanced PROTEIN ACCRETION.
But let's not forget the big picture here (below).
As far as 'optimization', this is a far more difficult
question and even John knows that this has not been answered
satisfactorily; or at least not to a degree that would make me
offer the advice that lifters should "eat more protein -
a lot more".
Again, I agree completely that "optimal" is a loaded
word and is a word that's nearly impossible to define. One man
might define "optimal protein intake" as a protein
intake that allows maximal functioning of all synthetic processes
that require amino acids and that prevents excessive oxidation
of amino acids and production of urea (Dr Phillips' choice).
And another might define "optimal protein intake" as
the protein intake that, when combined with sport-specific physical
training, produces ideal body size and composition for that particular
sport (which I would choose when working with an athlete or writing
an article with athletes as a target audience).
But regardless of the choice of the "optimal" definition
(Dr Phillips' or mine), BOTH are pretty damn hard to test and
with the current literature there is very little evidence as
to what is the optimal intake for EITHER definition. Of course,
there is SOME evidence, but as Dr Phillips rightfully pointed
out, it's based on some old N balance data that's probably not
valid anyway. So we're back to square 1. Not much evidence.
So what do we do in these circumstances?
Dr Phillips gets back to the lab and begins measuring this
stuff with some cool measurement techniques he's got at his disposal.
(Dr Lowery was at OEP and filled me in on some of the presentations
- good stuff!)
Me, since I don't have a lab of my own - yet - I wait for
Dr Phillips to publish his work. ;-)
But, in the meantime, I experiment with my athletes. Again, it's
tough to really control everything in free living humans but
I do a pretty damn good job. As a result, I know that when I
put athletes on higher protein diets those athletes see the following
benefits. I list these in response to Dr Phillips' comment: "while
it is easy to say eat more protein and counsel athletes to do
this what you have to ask at this point is what are the dividends
of eating more protein over and above requirement?"
1) Improvements in body composition. Now, I concede
that protein intakes above what the typical North American lacto-ovo,
meat eating male gets are probably not going to pack on additional
muscle mass directly from the additional amino acid load. However,
as stated in the article, perhaps the other components of the
protein foods are making an impact with respect to muscle mass.
But even more importantly, muscle mass is not the only endpoint
I choose when measuring body composition. For most performance
(aerobic or anaerobic) and physique athletes, the relationship
between fat mass and lean mass is critical - not just the absolute
amount of muscle mass. Consider this, some of the athletes with
the highest absolute amounts of lean mass on the earth are sumo
wrestlers. Need I say more?
A question - something to think about- something that isn't
answered in the literature but is CRITICAL when working with
athletes. If I have an athlete that needs to continue to train
hard and perform at a high level yet needs to lose body mass/body
fat to achieve the right body comp (or a better body comp) for
their sport, would I alter his/her macronutrient recommendations
or would I keep them the same as I would with an athlete who
has no fat to lose? It's a toughie…
Of course, we don't want to put this athlete on a calorie
restricted diet (or, at least, in a large calorie deficit) as
that might compromise performance ability and/or recovery. So
how do we get the fat off?
Here's what I'd do:
My solution (and it's worked time and time again) is to replace
some carbohydrates from the diet with protein. The thermic effect
of the protein may allow for more energy expenditure while still
taking in a large amount of total energy and, importantly, micronutrients.
Perhaps the BALANCE of glucagon to insulin may alter nutrient
partitioning. Or there might be something else at work (perhaps
something on the neurochemical/neurohormonal level) that we don't
even have enough evidence to speculate on.
I'm interested in your perspective on this issue, Dr Phillips.
Any suggestions about what else might be at work here?
Now, let me give a specific example of how this manipulation
might be carried out and what results one might see. I have a
cross country skier (national level) who went from 165 lbs to
135 lbs (with no net loss in lean body mass; measured via Bod
Pod) in 3 months without appreciably altering workout volume
or intensity (I worked directly with her coaches to verify this)
by increasing calorie intake by 1000kcal/day (via weighed food
records with the staff nutritionist) but going from a 70% carbohydrate,
15% protein, 15% fat diet to a diet containing 40% carbohydrate,
30% protein, and 30% fat (based on food selections I recommended).
Food selection and timing improved, of course, with my recommendations
so that's another variable. But, in the end, the major change
was an increase in kcal and an increase in protein at the expense
of carbs.
(Again, I concede there could be other factors at work, error
in dietary reporting, etc - but these errors would ALSO be present
in any chronic training/nutrition study and therefore should
not create a knee jerk dismissal mentality. These data are interesting
and need to be considered!)
To a similar end, I also have examples of athletes maintaining
body mass (while losing fat mass and gaining lean mass) after
an increase in protein intake at the expense of some carbohydrate.
(Importantly, this isn't a LOW CARB diet. These are alterations
that simply reduce carb intake percentages from the 60s and 70s
to the 40s and 50s while often increasing energy intake).
So my point is that for most athletes, body composition improvement
is often the goal - not absolute muscle mass. And from what I've
seen, increased protein intakes (with the appropriate dietary
shifts) are much more effective at achieving the alterations
most athletes need - less fat + preserved muscle OR less fat
+ more muscle while still training hard and recovering appropriately.
Perhaps the best paper demonstrating the potential for an
effect here is the Forslund paper (Effect of protein intake and
physical activity on 24-h pattern and rate of macronutrient utilization.
Am J Physiol. 1999 May;276(5 Pt 1):E964-76.) They showed increased
protein intakes (at the expense of carbohydrate) lead to a negative
fat balance and a positive protein and carbohydrate balance vs.
"normal" protein intakes. Surely this gives some indication
that an increased protein intake at the expense of carbohydrate
can lead, at least, to acute shifts in macronutrient balance,
the cumulative effect of such MAY be altered body composition
via nutrient partitioning. Thoughts?
2) Improvements in recovery and the ability to handle higher
training densities. Now, like "optimal", the word
"recovery" can be a nebulous term. So let me clarify.
Using both subjective and objective markers of recovery (POMS,
resting heart rate, heart rate variability, quality of sleep
indices, and - of course - daily performance), I've found that
my athletes can train with more density when the typical sports
nutrition recommendations of 60-70% carbohydrate, 15% protein,
and 25-35% fat are altered in favor of an increased % protein
intake and reduced % carb intake as mentioned above (as long
as rapid post exercise carbohydrate replenishment strategies
are utilized in order to ensure quick resynthesis of muscle glycogen
during the most "glucose tolerant" part of the day
- post exercise).
Of course, I often see large changes in body mass/composition
with these shifts so perhaps it's not necessarily the protein
increase or dietary shift that's creating the effect but the
simple loss of "nonfunctional baggage" as I call it
(i.e. body fat). Again, interesting reports none-the-less.
Now, a clarification has to be made in response to Dr Phillips'
comment "but then since they will never have tried doing
anything else do you get stronger, leaner etc because, or in
spite, of what you do". While some coaches may fall
victim to this, with each athlete I attempt rigorous reporting
and outcome-based experimentation. I do not put all athletes
on the similar diet, instead I use the first month or two as
a trial period to see which strategies/changes produce the best
results and then I do more of what has seemed to work.
With that said, these two benefits for the basis of my recommendation
for "more protein - a lot more." But let's remove the
"a lot" ambiguity and put some numbers on it.
After all, an 80kg athlete eating 4000 kcal/day and taking
in 30% of those calories from protein would be getting about
300g protein/day (3.75g/kg) and this is A LOT more than 0.8 or
even 1.4g/kg.
Interestingly, even at your recommendation of 15%, Dr Phillips,
a 65kg Tour de France cyclist, requiring in excess of 7,000 -
8,000 kcal (heck, even the spectators require a lot - I was at
last year's tour and lost a ton of weight because I simply couldn't
eat enough to get up those damn mountains every day) would be
getting 300g protein/day or a whopping (4 - 4.6 g/kg). That,
to me, is A LOT more than the 0.8g/kg recommendation or even
the 1.4g/kg suggestion by many sports nutritionists.
But mathematics aside, my point remains firm - myself and
many of those that I teach through my seminars and writing report
very similar effects with this type of dietary shift. I have
some guesses as to why these things occur but I have no firm
scientific support on all of these benefits.
However it's IMPORTANT to note that there aren't any firm
scientific objections either! And this is CRITICAL. If I'm doing
things that fly in the face of scientific evidence, I'm willing
to reappraise and throw out the chaff. However, in the absence
of BOTH scientific approval and rejection, there's no cause to
suggest that my methods are wrong - simply that they might not
be completely scientifically verified or even verifiable as of
yet.
Would I love the support, yes. It would silence some of the
critics (although they'll still yap away - some people just want
to criticize). However I don't really need it. The best test
of my consulting efforts is this - success with clients and repeat
business.
Hence, it does not appear that amino acid supply a) has
to be large; and b) is not limiting for the process of synthesizing
new muscle proteins.
Agreed, but again, I'm not merely interested in the synthesis
of new muscle proteins alone. It's the balance between fat mass
and lean mass that I'm most concerned with. And here's a major
problem with the lower protein recommendations (hinted at above
but not necessarily made really clear):
When you have an athlete overfeeding to gain mass or simply
eating a lot of total dietary energy to support energy expenditure,
the current recommendation is to shove carbs down their throats!
At 4500kcal/day and 65% carbohydrate we're talking over 730g
carbohydrate per day. Now, while carbohydrate energy does impact
athletic performance and does spare protein, could there be too
much of a good thing?
Getting 730g carbohydrate in the typical 4-5 meals an athlete
might eat/drink means huge carbohydrate loads that, with subsequent
huge releases of insulin, could lead to reductions in fat mobilization
and oxidation throughout much of the day - especially if this
chronic high insulin dump leads to neutralization of the improved
insulin sensitivity most athletes enjoy. Now, you said the following:
"Associated with protein ingestion is actually a pronounced
insulin response unless the protein load is enormous - John knows
this".
But I respond with: Certainly not more than the associated
insulin response accompanying a huge carbohydrate load. At least
with the protein load, some counter regulatory glucagon is released.
So my question to you, Dr Phillips, is this (it might be a bit
loaded and/or contrived but I'd still like to see your response):
If you had to overfeed an athlete (or simply have an athlete
ingest a very large daily energy intake) in an attempt to maximize
the lean mass to fat mass ratio and you had to choose a macronutrient
to "overeat", what would it be and why? (Keeping in
mind "overeat" might not be well defined in this context
- another way of saying it might be "choose a macronutrient
to eat more of"). This question assumes that they're getting
adequate daily energy intake (big assumption for most recreational
athletes and some elite athletes - but not much of one for the
athletes I work with directly).
My feeling on the whole issue of protein consumption is
that it appears to be beneficial to consume a higher than normal
protein intake during a period of weight loss, to prevent loss
of lean body mass. Lifting weights will only augment this effect
and will, IMHO, have the more potent effect in terms of allowing
one to hang on to as much protein as possible during energy deficit
- I know the scientist finally agrees with the strategy tried
and tested by body builders for years.
I agree 100%...during periods of weight loss, there's no question
(or really any reason for equivocation - the research is clear).
Also, what about elevated homocysteine, an independent
risk factor for cardiovascular disease, on high protein diets?
Is this a legitimate concern or simply a secondary or tertiary
debate point? Admittedly, I'm not an expert on homocysteine and
heart disease so forgive any ignorant comments - I'm assuming
that the speculation here is that high dietary methionine would
lead to higher serum homocysteine concentrations as a result
of methionine's demethylation via the methyltetrahydrofolate
reductase enzyme pathway?
If so, recent literature shows that a) dietary methionine
increases homocysteine to a lesser extent than free methionine
and b) the dietary cysteine and serine attenuate any increases
in homocysteine as a result of methionine intake. (Verhoef -
Dietary serine and cystine attenuate the homocysteine-raising
effect of dietary methionine: a randomized crossover trial in
humans. Am J Clin Nutr. 2004 Sep;80(3):674-9.)
Furthermore, if this is the ONLY potentially serious health
consequence of a higher protein diet (and increased homocysteine
is not universally regarded as a "real risk"), and
the ingestion of cysteine and serine (present in high protein
diets also) doesn't take care of the homocysteine, daily folic
acid supplementation should take good care of that (and would
offer other benefits) as discussed in (Treatment of coronary
heart disease with folic acid: is there a future? Am J Physiol
Heart Circ Physiol. 2004 Jul;287(1):H1-7. Review. No abstract
available.).
Here's the concluding paragraph from that paper:
The view that a raised plasma tHcy level is causal in the
development of vascular disease is an attractive hypothesis if
only because folic acid offers an easy, inexpensive, and generally
safe means of lowering it. This review challenges the hypothesis
that tHcy is causal and raises the possibility that an increased
tHcy is an epiphenomenon. Moreover, there is evidence that the
beneficial vascular effects with folic acid are only achieved
in pharmacological doses. Low-dose folic acid will reduce plasma
tHcy, but a high dose may be required to produce the beneficial
effects on vascular function, which occur before, and apparently
independently of, homocysteine lowering. The current clinical
trials are on the whole designed to test the homocysteine hypothesis
of vascular disease using relatively low doses of folic acid.
While these trials will undoubtedly show that folic acid lowers
tHcy effectively, it is unlikely that the expected reduction
in cardiovascular events will be seen. However, it is important
therefore not to discount treatment with folic acid if these
trials are negative, because it is possible that high-dose folic
acid may have a beneficial effect on outcome via mechanisms independent
of homocysteine lowering. Elucidation of these mechanisms is
important in the drive to develop effective treatments for prevention
of CHD.
So is this an actual concern?
In the final analysis requirement or 'optimization' the
argument is moot. Available evidence (Tarnopolsky Journal of
Applied Physiology 73(5): 1986-1995, '92) as well as hypothetical
calculations are not consistent with the tremendously elevated
protein needs John says must exist.
Yes and no. For protein status or positive protein "balance"
- perhaps. But isn't focusing on this one outcome variable a
bit too isolationist for you as an inquisitive individual? After
all, isn't there so much more to nutrition than focusing on 1
physiological outcome - protein turnover? Aren't athletes (even
just physique athletes) after something much more than just an
improvement in protein synthesis? As mentioned earlier, athletes
are after the balance between lean mass and fat mass. They're
after optimal biochemical conditions for performance. And they're
after recovery of every system - from muscular to neural to immune.
In my estimation, focusing on the protein status response
to protein intake alone is committing an error - perhaps the
same error many sports nutrition people are making with their
chronic focus on high carb diets.
Think about it - high carb diets evolved to be the recommendation
for athletes because of the original studies showing that high
carb diets lead to high muscle glycogen. And high muscle glycogen
seemed to correlate with good performance (in endurance events,
no less). So the sports nutrition community has based its entire
recommendations on one thing - muscle glycogen.
What about all the other stuff that supports training, immune
function, etc?
Now, with this as an analogy, are we doing the same thing
if we stick to the argument that since aminos aren't limiting
one potential body comp outcome - protein turnover - that we
can ignore protein from there on out?
From this perspective, I'm not quite sure EITHER of us can
jump to any conclusions with firm protein intake recommendations
for athletes until we answer a few important questions such as:
- Could altered intakes of protein impact immune function?
- Could they impact body composition?
- i.e. the all important balance between fat mass
and muscle mass.
- not just muscle mass in isolation.
- Could they impact the neurochemical/neurotransmitter balance
in the body?
- Could they impact hormones that lead to body comp changes?
- Could they lead to alterations in physiological set points
for cellular function?
- Could they alter CNS function?
- Could they offer OTHER nutrients that support body comp changes?
- Might individual differences govern the responses to each
of the 7 aforementioned questions?
Until these questions are answered, each of our conclusions
about what's best for athletes - from a dietary perspective,
are based only on a very, very small glimpse of what might be
going on when we alter macronutrient intakes. So I guess this
is where we reach the impasse.
I'm sticking to my concluding statement in my review, since
I see no true evidence to support any other recommendation otherwise;
namely, that 12-15% of ones energy should come from protein.
I agree that the literature has little to offer in the way
of comprehensive dietary suggestions for athletes seeking to
find their best competitive body composition, immune function,
CNS balance, etc.
However, as I stated earlier, sometimes we have to operate
in the void where literature is lacking. To operate within that
void, I've done some pretty cool, albeit loosely controlled experiments
on small sample sizes to come up with my own conclusions. And
in this realm, I'm sticking to my recommendations - more protein.
Of course, this statement "more protein" is a gross
oversimplification. Caveats include - macros can't be viewed
in a vacuum, "more protein" must be matched by appropriate
shifts in dietary carbohydrate and fat, and these suggestions
may have behavioral implications in free living humans that can't
be controlled.
(Of course, my original article didn't touch on much of this
and that was, admittedly, a
weakness…but such is the article format. If you tried to
cover it all, it wouldn't be an article, it would be a book.
But if you kept telling the story it wouldn't be a book any longer
- but a volume of books. And so on. So you've gotta stop somewhere,
leaving stuff out along the way based on your judgment).
Thanks for the discussion and the forum to share these types
of ideas.
JB
PS…One more caveat - Dr Phillips, I'm sure that we can
agree to disagree but let's do so officially at ACSM where, regardless
of its low protein content (usually 0.3 - 0.5%), you'd better
let me buy you a beer!
