The Protein Interview: An Interview with Dr. Stuart Phillips

April 17th, 2014 by



Dr. Stuart Phillps, in addition to being a full Professor in Kinesiology, is also an Adjunct Professor in the School of Medicine at McMaster University. He is a fellow of the American College of Sports Medicine (ACSM) and the American College of Nutrition (ACN). His research is focused on the impact of nutrition and exercise on human skeletal muscle protein turnover. He is also keenly interested in diet and exercise-induced changes in body composition.

Recently I had an opportunity to interview him regarding several things pertaining to protein, training, and muscle hypertrophy to see what the latest research has to say about these topics.  Without further ado, let’s get to the interview.

Okay…let’s start with the basics.  Can you give us a general guideline as to what the average protein requirement might be for a trained lifter? And does that requirement change if a person is in a calorie deficit versus being in a surplus?

I like to make an early distinction between protein requirement and optimal protein intake (OPI). I don’t think there’s any evidence to suggest that a lifter’s protein requirements are any greater (and perhaps even less) than the protein RDA. From an optimal standpoint, however, there are
benefits of ingesting protein intakes as high as 1.6-1.8 g/kg/d [0.73-0.81 g/lb/d], which we further breakdown to ~4 meals of 0.4-0.45 g/kg/meal, in a day.

In an energy deficit higher intakes might be of benefit to protect muscle mass, but the exact number for what to eat when in energy deficit is a little hard to pin down, but I’d have no issues with 2-2.5 g/kg/d [0.91-1.14 g/lb/d] or 0.5k/kg/meal 4 times daily. Some people are advocates for higher intakes but I just don’t think that those intakes feed into any useful metabolic process – like muscle protein synthesis. You can certainly eat more protein, but it’s not doing anything too useful for you!

Oh and I like 4 meals per day as opposed to 5-6.

[Note: I asked him about this after the fact and he said that consuming 5 or 6 meals as opposed to four offers no additional benefit.  However, if you prefer 5 or 6 meals in the interest of having to get in a lot of food in a day, that would be fine.]

Do you believe that there is any truth to the notion that there is a certain maximum amount of protein that can be digested and/or utilized in a single meal?

Well as I said above there’s a useful limit but I think that’s reflected in the intakes I’m talking about above. While our group has continually been tagged with the 20g/meal tag (which equates to ~0.25g/kg), you can certainly eat (and digest) a lot more protein. My point would be that your body can’t use the amino acids from protein when ingested beyond the immediate roles of those amino acids to build new proteins – in muscle and elsewhere – make neurotransmitters, or use the amino acids in intermediary metabolism.

After that the nitrogen (N) is fundamentally toxic in a mammalian system and you strip the amino acid off the nitrogen and eventually it ends up in urea and some ammonia. So beyond what your body can immediately (or within a few short hours) use metabolically, large ‘doses’ of protein simply aren’t metabolically useful. So If you eat 100g of protein, you digest it, absorb it and use some of it (I’d estimate ~25-35% for protein synthesis) and the rest has the N stripped off, and the metabolic carbon ‘skeletons’ are metabolized.

There have been some people lately talking about the risk of consuming dairy or even just the dangers of a moderate to high protein diet?  Is there any truth to any of this?

I can’t see too many dangers of a high dairy or a high protein diet. The bulk of evidence, beyond the usual poor-logic arguments, suggests that
dairy is quite protective against a number of metabolic and cardiovascular disease and even some cancers. The recent high protein diet ‘scare’ is quite simply based on a flawed interpretation of some poor data as myself and some other researchers tried to get the point across here.

The old demons for a high protein diet are always kidney disease/failure and/or bone loss. Quite simply folks who talk about these as big deals just aren’t informed. First, even the WHO and Institute of Medicine (IOM) agree that there’s no link between protein and renal health. Second, so long as you’re getting adequate calcium and vitamin D then protein has no detrimental effect on bone health; in fact, higher protein may even enhance bone health. Practically, however, I think there are some true upper limits to protein intake that are around 3.5 g/kg/d [1.59g/lb/d] beyond which it’s a useless practice to consume more and more protein and it’s time to think about other macronutrients to make up your energy intake!

Do you feel that the evidence still supports the need for post-workout nutrition?  If so, what would your recommendations be with respect to protein and carb intake after weight training?

I think it’s pragmatic advice to get some kind of post-workout nutrition rather than none. I think, however, the importance of the immediacy of getting your post-workout protein shake is overblown. The recent study from Brad Schoenfeld shows just how unimportant post-exercise nutrition is in determining muscle gains. So my advice is still to get some post-workout protein, and likely some carbs too, but if you don’t get it for a few hours don’t sweat it.  Your body will still make very good use of the protein then and you won’t compromise your gains.

As to the optimal protein/carbohydrate ratio I don’t believe there is one. We know for sure that ingestion of ~0.25g/kg of protein (or more. see above) will maximally stimulate muscle protein synthesis and that should work across the day. I do think that if there is a time for getting a little carbs in it’s post-workout so your muscle can restore muscle glycogen levels.

Some people still believe in a very small window of opportunity to get in your post-workout nutrition.  Can you shed some light on the length of the post-workout window for getting in the proper nutrition to maximize the anabolic response?

Well, as I said in answer to the previous question, the post-exercise anabolic window is not some short 30 minute window and, in fact, anytime in
the ensuing 24h after a workout is a good time to eat protein. Work from our group has shown that your muscle is ‘sensitized’ to the effect of protein for at least 24h after a workout.

I might agree that the time from at least immediately to 3h post-exercise is a time when your muscle is even more sensitive to protein.  However, it’s not a big difference between that time window and much later. So, as I said above, it’s still prudent to consume your shake immediately post-workout, but it’s not critical.

Do you feel that branched chain amino acid supplements are of any value to the typical lifter who already consumes a very protein-rich diet?

In short, no! The evidence on BCAAs is remarkably weak as to their positive effects and they are not anabolic. They may be mildly anti-catabolic if you’re in negative energy balance, however, protein (especially whey) is going to be both anabolic and anti-catabolic. Bottom line, if you’re taking in adequate protein then BCAA are a complete waste of money IMO!

Do you believe that it is possible for people to gain muscle while in a calorie deficit to lose body fat?  If so, does that ability differ from novice to very trained lifters with multiple years of experience?

Yes, it’s possible to lose fat and gain muscle at the same time, but it requires a few things to be in place. First, protein has to be higher – up to around 2-2.5 g/kg/d [0.91-1.14 g/lb/d]  (05.-0.6 g/kg/meal x 4 meals) – and timing of protein post-workout is perhaps more critical in this situation. I favour cutting carbs to promote fat loss, but wouldn’t say a drastic reduction is necessary. I’ve come to realize that weight loss is a very individual practice and what ‘works’ for some folks doesn’t work as well for others. I don’t think there’s any evidence that one method of weight loss is vastly
superior to another.

If you’re a novice and have, in all likelihood, more fat to lose then there’s more room to make changes so you may notice bigger relative shifts than if you’re an experienced lifter. Nonetheless, I think the simultaneous fat loss and muscle gain is possible in both, but if you’re already down to a low body fat level to get lower you may be compromising some lean mass since there is a point when no amount of protein and lifting can ‘rescue’ muscle loss. I don’t know where exactly that threshold is, but when your dietary energy drops below 20-25 kcal/kg my guess is most will start to struggle with muscle retention!

[Note that 20-25 kcal/kg represents about 9-11.4 kcal per pound of body weight.  For fat loss we typically recommend that people set their caloric intake between 10-12 x body weight (in pounds) for optimal fat loss.  As this falls within the range where people may have a harder time hanging on to muscle, it makes sense that we also say that muscle retention (rather than building) should be your focus when your primary goal is to lose body fat.]

You’ve been doing some interesting work in your lab looking at the differences between low rep and pretty high rep protocols for building muscle.  Would you say that one rep range has turned out to be superior for muscle gains than another?  Or is it safe to say that using both high and low rep ranges can elicit muscular growth?

It’s funny how much people have taken to heart what we did and have thought we used the low intensity paradigm as a ‘new way’ to lift! All we wanted to do was show that a critical factor in hypertrophy was a maximal, or near maximal muscle fibre activation. Simply put, when you lift to a good level of fatigue, which comes close to eliciting full muscle fibre activation, then you begin to see hypertrophy.

Practically speaking I’m not sure I’d ever recommend to someone interested in getting stronger to lift lighter weights. We knew even beforehand it wouldn’t promote big strength gains (those are as much a neural phenomenon as anything), but it can promote growth. Is it better than heavy weights? Likely not! Is it worse? Well if it is ‘worse’ then it’s not much worse!

In other words, if you’re not feeling like you can crush a big set of weights, or you have an injury that prevents you from lifting heavy, or perhaps you’re just feeling ‘flat’ and need some ‘rest’ then our message would be that backing the weight off – perhaps quite substantially – means you can still maintain your gains in muscle and perhaps gain!

Blood flow restricted training has become increasingly popular in the bodybuilding world.  What are your thoughts on this?  And do you think that its potential effects would bring about even greater muscular gains than could otherwise be had by conventional means in trained lifters?

The blood flow restriction (BFR) lifting paradigm is an interesting one but one that I think isn’t ever going to gain a huge following since it’s not practical for all lifts and it can be, at least in my experience, rather uncomfortable.

Nonetheless, studies have shown you can get, in novices, gains in muscle mass and strength with relatively low loads vs. much higher loads. I suppose it’s the same answer to the question above. Is it the same, worse or better than regular lifting of heavy weights? I think the answer is that in novices it may well be as good as heavy weights, but I don’t think anyone would chose to use BFR training all the time.

In experienced lifters I think BFR training is much like higher-rep-lower weight range training in that it gives the muscle a ‘rest’ and mixes things up a little. Is BFR better than regular lifting? I don’t know of a study that has shown that, but never say never!

Is there any new research on muscular hypertrophy coming down the pipe that might be of interest to our readers?

Well, we’ve conducted several large training studies now and I’ve seen a variety of gains from nothing (hard gainers) to men and women who literally grow before your eyes. One thing that intrigues me is that there is likely some common genetic program governing all this. It’s has to be a complex program because muscle hypertrophy is not a simple yes/no phenomenon. Instead hypertrophy involves multiple organ systems and so it’s unlikely that one or two, or even seven or eight genes are going to capture who gains muscle and who does not.

So we’re working on a looking at trying to define a genetic program that will capture as large a portion of the variance in the hypertrophic response as possible. With that in hand we might be able to tell people what they can expect and perhaps what they might do to ‘tweak’ the response. But, and this is a big but and not one some folks like to hear, I don’t think you can cheat the genes that much. In other words if you’re a gainer then so be it, good for you. If you’re not then you’re not. There is some room to move within the spectrum, but I don’t think you can move too far within the response range.

If you were to give some final advice of maximizing muscle hypertrophy for an advanced lifter what would it be?

For the novices: know your goals and if you lose track remind yourself why you started, get to the gym, be consistent in the practice of your workouts, your nutrition, and know your goals. Yeah, I know I said that twice. It’s important! Consistency of practice wins in the end no matter what your goal is. No diet, supplement, or other training crutch makes up for a poor (or no) workout.

For the advanced lifter: train hard, but be smart and know it’s a long-term game. One poor workout (or a missed workout) isn’t the end of the road. Stay focussed and remember the stuff you do in the gym and your diet are what give you the gains you make and most supplements are fluff compared to what you can achieve with a good diet!

For both: If there’s a new supplement that sounds too good to be true it probably is! If it works, it’s likely illegal. There may be one or two
exceptions.  ;-)

Thanks Stu!  I really appreciate you taking the time to provide some insightful answers to our readers.

My pleasure.