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Gary Slater, PhD is an advanced accredited sports dietitian who has been working in elite sport since 1996. Gary currently splits his time between coordinating a Master’s Degree in Sports Nutrition at the University of the Sunshine Coast and his role as Performance Nutrition Lead for the National Sport Science Sports Medicine network of the Australian Institute of Sport. He also consults to professional teams and an array of individual elite & recreational athletes. Gary has supported athletes attending major international multisport games including 2006 Asian Games, plus 2008 and 2016 Paralympic Games. His professional interests relate primarily to enhancing sports performance. Gary is particularly passionate about factors influencing muscle protein metabolism and muscle hypertrophy/atrophy, nutritional recovery strategies, ergogenic aids and the influence of body composition on sports performance.
Eric Helms, PhD, CSCS is a nutrition, sport science, and exercise/sport psychology researcher/practitioner with a mission to support the lifting community. He is co-founder and chief science officer for Team 3D Muscle Journey, chief author of the Muscle and Strength Pyramid books, co-founder and contributor to the Monthly Applications in Strength Sport research review, co-host of Iron Culture Podcast, and a Strength & Conditioning Research Fellow in the Sports Performance Research Institute New Zealand, at the Auckland University of Technology. He’s coached 100’s of recreational and competitive physique and strength athletes from novice to world champion, published scores of peer-reviewed articles on strength and conditioning, psychology and nutrition as they relate to physique and strength sports, and authored book chapters for strength and conditioning, nutrition, and personal training professionals. In his personal life, Eric is a multi-sport lifter, earning a professional qualification in drug free bodybuilding with the PNBA, and competing in powerlifting, weightlifting, and strongman.
Eric: Thanks for the offer to interview us, it’s an honor! My name is Eric Helms. At my core I love lifting. I compete in powerlifting, weightlifting, strongman and drug-free bodybuilding. I was bitten by the iron bug in ‘04 and since then, it’s been my intellectual, physical, career, and spiritual focus. I have a PhD in strength and conditioning, a master’s in sports nutrition, a second master’s in exercise science, a bachelor’s in fitness and wellness, and I’ve had just about every nutrition, strength and conditioning, and personal training certification under the sun. I am an active researcher, science communicator, and coach for strength and physique sports. I am a research fellow at the Auckland University of Technology in the Sports Performance Research Institute New Zealand. There I conduct research and supervise master’s and PhD students in the areas of strength and conditioning, sports nutrition, and mental health and performance. I am a co-founder of Team 3D Muscle Journey along with Alberto Nunez, Andrea Valdez, Brad Loomis and Jeff Alberts, where I work with a few athletes, write blogs, podcast, create courses, and am the Chief Science Officer to my colleagues. I am also a co-founder of the research review Monthly Applications in Strength Sport (MASS) alongside Dr. Eric Trexler, Greg Nuckols, and Dr. Mike Zourdos, where I produce video and written reviews. I also co-host the Iron Culture Podcast with Omar Isuf. Lastly, I’m the chief author of the Muscle and Strength Pyramids books alongside my co-authors Andy Morgan and Andrea Valdez.
Gary: Really happy to talk shop on an area I have a real interest in professionally and personally. I’m just a geeky scientist with a passion for performance nutrition and helping athletes achieve their sporting ambitions. I started my journey by undertaking an undergraduate degree majoring in exercise physiology, before completing dietetic training, followed by a research master’s (impact of HMB supplementation on resistance training adaptations) & PhD (body mass management of lightweight rowers). I was really fortunate early on in my career to get an opportunity to take up a fellowship at the Australian Institute of Sport (AIS) under the guidance of Professor Louise Burke. That was a sliding doors moment for me, getting an opportunity to learn from and work with some of the smartest minds in the business. As well as Louise, colleagues like Dr Greg Cox and Greg Shaw create such amazing learning opportunities because of their unique ability to combine great research minds with progressive skills in delivering innovative support for their athletes. It was an environment that really set me up professionally. I left the AIS in 2009 to take up an opportunity to be closer to family and friends (as well as surf) while coordinating a Master’s Degree in Sports Nutrition at the University of the Sunshine Coast (USC) and continuing to consult within professional sport. Much of this was focused on rugby union, working with big athletes trying to get bigger. I’m now full circle, still with USC but also back at the AIS helping to facilitate the network of performance nutrition practitioners across Australia.
Thanks. So, let’s chat about your recent review article, which summarized the evidence surrounding the impact of energy surplus on muscle hypertrophy when coupled with resistance training.
Q. Before we jump into the science, I’m curious: what led you to want to collaborate to tackle this question in the first place?
Gary: My original PhD candidature plan was to research this very issue but given my background in physiology and nutrition my supervisory team at the AIS decided it would be best I collaborate with the AIS lightweight rowing program. Given these athletes are similar to other weight category sport athletes, their interest was in facilitating fat loss via an energy deficit, not lean mass gain from a surplus, so a change in topic was necessary. This paper has been 20 years in the making. The opportunity to collaborate with some great minds came about while I was at the Norwegian Olympic Training Centre on sabbatical in 2018. During that time I met Juma Iraki, who’d already been doing some work with Eric and his peers. We had similar interests in hypertrophy work and saw an opportunity to help stimulate some research in the area given gaps in the literature.
Eric: For me personally, this is an interesting area because it’s one of those topics with a ton of anecdotal evidence, and also mixed messages coming from the fitness community. But, it has very little high quality, relevant research behind it. Gary approached us (I’m just one of a number of contributors) with his take on the topic, informed by the research he’d seen, his experiences in the trenches, and we all had similar but not identical views. In areas where there is a lot of consensus, you’ll often have multiple meta-analyses, or a lot of high quality RCTs which inform that consensus. There ends up being a lot less to disagree on, as there are fewer holes in the data, and less room for speculation. In this area, however, we have barely a handful of studies, each with a set of limitations, and a lot of indirect data that could be interpreted in many different ways. In cases such as this, collaboration is really useful because we aren’t all informed by reading the latest position stand or meta-analysis, we each bring our unique thoughts to the table and hopefully, by collaborating, we’re able to get closer to the truth by providing a more comprehensive view of the topic.
Q. Before diving into energy intake’s influence, I wonder if you can talk a bit more about the big picture point-of-view. Specifically, for someone who’s solely interested in hypertrophy, what’s the biggest-impact thing they can do to boost it? Would it be improving stimulus somehow (e.g., through periodization or better progressive overloading)? Making sure they get enough protein? Something else? Or perhaps the answer depends on the person?
Eric: I think big picture, it’s really important to understand that without a progressive tension stimulus to the muscle, the entire cascade that results in hypertrophy is not going to occur to any robust degree. I like to use the thought paradigm that nutrition is permissive to muscle growth, while training is the root stimulus. While there are overfeeding studies that don’t include training where increases in LBM occur, these are a) often not measuring hypertrophy directly; and thus, these increases may not be muscle (this could be glycogen, water, or other lean tissue) and b) they are much less robust in magnitude than even resistance training studies when a caloric surplus isn’t intentionally part of the intervention. Some increases in LBM are likely obligatory when gaining weight, as adipose tissue is not completely comprised of fat. Likewise, simply weighing more and maintaining the same activity level may require a bit more muscle and bone to be developed to support the increase in mass; in essence, gaining weight and doing any movement is some form of progressive overload - but that’s different than saying a caloric surplus is the direct cause of muscle gain. So to directly answer your question, making sure the stimulus is optimized is the first go-to from an athlete or trainer perspective. Then, the next step would be to ensure that the optimal environment to support that stimulus is present, which includes all the nutrition aspects, as well as recovery aspects (sleep etc.).
Gary: The exercise stimulus for hypertrophy is absolutely essential — nutrition support merely amplifies the resistance training signal. Numerous studies have shown that muscle hypertrophy occurs in response to resistance training, even with less-than-optimal nutrition support, at least in previously untrained individuals. However if you want to optimise the hypertrophy response, then it’s wise to give consideration to both the resistance training stimulus and nutrition to assist in amplifying the adaptation. There is now a significant body of research confirming that nutrition support can help facilitate adaptation. Certainly there is evidence that optimisation of dietary protein intake plays a role yet as a practitioner there are a range of other variables I give consideration to, including an adjustment in energy intake.
Q. Let’s move on to the meat of your review article, dealing with caloric surplus. You mention that common textbook energy surplus recommendations for hypertrophy are based on theoretical calculations that assume that skeletal muscle is the sum of its parts; given the composition of skeletal muscle, just add up how much energy is needed for the body to synthesize each part, and that gives you an idea of how much energy is needed to build more muscle. Why do you find this approach lacking, and how close are we to truly understanding the impact of caloric surplus on hypertrophy?
Gary: What this approach fails to consider is the actual metabolic cost of generating the tissue that comes from the resistance training stimulus. In the paper we describe this as the metabolic cost of increased protein turnover. Aside from the metabolic cost of generating skeletal muscle, there’s also the metabolic response to the energy surplus itself (most likely an amplification of diet-induced thermogenesis), plus the impact this can have on non-exercise activity thermogenesis. There’s a whole lot of balls moving at once.
There has been very little applied research in this space, with much of the work theoretical. I would love to see some metabolic ward work in this area, as has been undertaken in some tightly controlled overfeeding studies, but inclusive of the resistance training stimulus. These would clearly be very resource-intensive investigations, likely capturing data on a single individual at a time, preferably over a 6-8 week period. You can imagine how hard it would be to recruit for such a study. What’s more, our techniques for assessing metabolic and physique adjustments just don’t have the resolution many are led to believe. There is still much to learn in this space. We’ve highlighted several of these topics in the paper itself… a great start for any budding post-grad students looking for a research focus.
Eric: Correct. The calculations of simply looking at muscle tissue, and assessing its energy content is basically the same way we view food, assessing it’s caloric content. However, this calculation doesn’t take into account that our body has to grow that tissue. There is an energetic cost to actually building muscle. Technically, this is not actually part of the surplus itself (I’ll explain in a moment), but from a practical perspective, still needs to be considered. What I mean is, that the cost of building muscle is a metabolic expenditure; in the energy balance equation it adds to your TDEE. Thus, it is not technically correct to say the surplus needs to be larger than the sum of the parts of the energy content of muscle, but rather, the process of building muscle is so metabolically expensive that you might have to increase your energy intake more than you’d expect ‘on paper’ to get into a surplus, and gain weight. Actually getting into an energy surplus requires a larger than expected increase in calories, which can be further exacerbated by increases in TDEE due to adaptive thermogenesis in response to weight gain/ the caloric surplus (principally via increase in non exercise activity thermogenesis and the thermic effect of food), increases from energy expenditure from added exercise (and added strength, as you move heavier and heavier weights, each rep burns more energy), and a small increase in your energy requirements as you gain mass. To answer the last part of your question, the impact of a caloric surplus on muscle gain is still something needing study, but as to our best guess right now, the more “capacity for growth” you have, the larger surplus you can support before it becomes excessive and just results in more fat gain without any further increase in muscle mass.
Q. If I understand your review article correctly, there’s a lot of uncertainty not only in how many calories people aiming for hypertrophy should take in, but also the relative macronutrient percentages needed. However, you do recommend that it’s prudent to take in the minimum macronutrient levels. Can you review the recommended minimum macro percentages for resistance-training athletes, and tell us how firm you think the evidence is concerning relative macro contributions to hypertrophy?
Eric: I’ll let Gary discuss the paper’s quantitative recommendations, but I will say the guidelines for specific macronutrients are lacking high quality research. What we do know is that the size of the surplus is likely the biggest factor that dictates the amount of muscle mass gained, but only to a point before diminishing returns occur. Meaning, with too large of a surplus the efficiency of the ratio of lean:fat mass gains fall off. Too large of a surplus is problematic unless you don’t care at all about fat gain. However, there may be something to manipulating macronutrients to try to make the gains “leaner”, but we need more data to confirm this.
This is speculative, but from some of the research by Jose Antonio and colleagues, while very high protein diets (>2.2g/kg) may not enhance muscle growth more than intakes in the range of 1.6-2.2g/kg, they may mitigate fat gain. Also, we know from overfeeding studies (unfortunately not during resistance training) that the conversion of carbohydrates into adipose tissue is a more metabolically inefficient process than the conversion of fat to adipose tissue. Thus, I think we need research to explore macronutrient strategies to mitigate fat gain in a surplus. Specifically, I would love to see a head to head comparison of two interventions with the same sized surplus, with one group consuming 1.6g/kg protein, 1g/kg dietary fat, with remaining calories from carbohydrate (these are probably the stock standard sports nutrition recommendations), compared to a group consuming 3g/kg protein, 0.6g/kg dietary fat, with remaining calories from carbohydrate to see if you can mitigate fat gain with a low fat high protein macronutrient breakdown — and if you can, does this also come at the cost of slowing the rate of muscle gain?
Gary: I really prefer to work with absolutes (relative to body mass) rather than a percentage of intake from macros as percentage calculations are dependent on energy intake. For example, an athlete may be getting 20% of energy intake from protein but if energy intake is markedly compromised, protein intake is likely to be inadequate when described relative to body mass. I think the body of research on optimisation of protein intake for resistance trained individuals is now quite mature thanks to work by players in the field like Stu Phillips, Luc van Loon and Kevin Tipton. However, far less is known about needs for carbs and fat for resistance trained athletes. Certainly the often cited sports nutrition guidelines for carbohydrate are likely specific to endurance trained athletes. Certainly, I’ve rarely had a resistance focused athlete consume 8-10g/ kg body mass on a regular basis. Instead I’ll likely work within the range of 4-7g/ kg body mass but that’s still upwards of 700g of carbs daily for a 100kg athlete. Why such broad guidance? Well, in part to accommodate individual nuances but also because of markedly varying needs between training and recovery days. Far less is known about dietary fat requirements but I see the use of healthful fat sources like nuts, avocado, olive oil etc as a really easy way of fortifying both energy as well as overall micronutrient intake, especially for those with very high energy needs.
Q. You also mention that energy balance timing hasn’t really been investigated for resistance-training athletes, but there’s some preliminary evidence that timing could matter. Where does the preliminary evidence point in terms of timing caloric intake, and how solid is the evidence base at this point in time?
Gary: There is some emerging obesity research suggesting that timing of daily energy intake may influence the risk of overweight or obesity. It has been reported that the risk of overweight and obesity may be as much as twice as high in populations who consume the majority of their daily energy intake towards the back end of the day. While there may be some metabolic reasons for this, it could also simply be that energy consumed earlier in the day has greater satiety than that consumed at the back end of the day. Reverse engineering this to a resistance training population aiming to facilitate gains in muscle mass while maintaining fat mass, it could be argued that more of any energy surplus should be placed earlier in the day. In practical terms, I aim to do most of this in and around training, not only because it better aligns energy intake to expenditure (assuming the highest energy expenditure over the day will be during training), but also because fits nicely with accepted sports nutrition fuelling and recovery goals of athletes. While there is some preliminary evidence to support this concept in resistance training populations, I’ve had some great responses from athletes I work with using this approach. Of course, it’s also important to remember that whenever you are manipulating the timing of energy intake, you’re also manipulating the timing of macros.
Eric: This is something that is getting a lot of indirect focus and also attention outside of sports science. First, there is a ton of protein timing research that suggests you may benefit from having as many spikes in muscle protein synthesis (MPS) throughout the day as possible. However, there is a feature of skeletal muscle that it can only be stimulated to increase MPS every few hours; thus, it makes sense to consume more moderate boluses of protein every 3-5 hours or so, and perhaps to try to consume a slow digesting protein before sleeping when you won’t have an opportunity to (and probably shouldn’t, to not disrupt sleep) eat. However, this research is almost entirely composed of mechanistic lab-based research which, to date, hasn’t panned out in real world settings. This disconnect is likely because the kinetics of digestion when consuming a high protein mixed diet of whole foods (versus being fasted before coming to the lab to only consume powder) means that you almost always have available amino acids to support muscle growth. So how important the collective protein timing strategies are is up for debate, but at the moment I think our consensus is that if the goal is to optimize hypertrophy, it’s to take a better safe than sorry approach and consume a slow digesting protein before bed, have protein within 1-2 hours of training, and over the course of the day get at least 3 protein feedings in total.
Outside of sport science, there is a lot of interest in chronobiology and how food can modify and be modified by your circadian rhythm. There is emerging data to suggest metabolic health, longevity, and sleep quality may be better when you have a smaller feeding window, don’t eat prior to bed, and perhaps bias your carbohydrate and fat intake to earlier in the day. I’m by no means an expert in this area, but I could plausibly see down the line, once our line of research is investigated further, as well as the science of how chronobiology interacts with nutrition, that there might be some conflicts and trade offs when eating to maximize health vs maximize muscle mass. For example, it might be better to only eat 2-3 meals per day in an 8-12 hour period, specifically not in the few hours before going to bed and not be in a chronic caloric surplus from a health perspective, but it might be better to eat every 3-4 hours while you’re awake including before bed, and be in a chronic surplus when trying to gain muscle. There likely are some paths where you can try to get the best of both worlds, like making the surplus only as large as necessary, and making the last meal comprised only of protein and only as much as needed, but the idea that the two eating patterns are not totally in line I think is unfortunately plausible.
Q. In your article, you briefly mention that learning more about calorie and nutrient timing may be useful not just for athletes, but also people with certain clinical conditions where keeping or gaining lean mass could be important. What clinical conditions do you think would be most impacted by learning more about nutrient timing for maintaining and gaining lean mass?
Eric: Sarcopenia, the age-related decline in skeletal muscle mass, as well as muscle wasting diseases can have disastrous effects on health. Just like athletes could use our strategies to put on muscle, individuals dealing with these clinical problems could potentially be aided by the same strategies to help them retain muscle.
Gary: I think there is clear application of these concepts to sarcopenia, and perhaps other conditions characterised by a loss of muscle mass, including cancer cachexia. Again, the exercise stimulus remains paramount but the nutrition strategies we make mention of may assist in amplifying the resistance training response.
Q. Would you like to mention anything else that our audience may be interested in that I may have missed?
Gary: This paper will likely be known more for the questions it asks, than the questions it answers. Hopefully the paper stimulates interest amongst researchers to assist in helping to answer some of these fundamental questions, the results of which will really help practitioners to better guide athletes on dietary strategies to support skeletal muscle hypertrophy. The challenge is that factors such as training age likely play a significant impact on adaptations and with that, most likely the fine tuning of dietary interventions. With this in mind, optimisation of individual prescription is likely to come from the close monitoring (of physique and performance characteristics) of evidence based approaches, with subsequent refinement based on how the individual responds.
Eric: One thing I would like to mention is that our guidelines are intended to reach the broad population of those seeking muscle gain. This includes new lifters, athletes in the offseason during certain phases who don’t have a main focus of gaining muscle, those in the general population trying to mitigate sarcopenia through lifting weights with good nutritional support and as you brought up before, potentially clinical populations. However, in each case, many of these populations have a large potential to gain muscle mass. As the resident bodybuilding/ strength sport researcher, it is my due diligence to mention that the size of the surpluses we recommend in this paper are probably a little too aggressive for very experienced lifters. Those who have gained the lion’s share of their muscle mass potential who follow too aggressive of a surplus, may gain excess fat mass that could reduce the power to weight ratio unnecessarily, or prolong a fat loss phase for competition or make it too aggressive, and in either case less effective. For strength and physique athletes specifically, I’d recommend they take a look at the open access paper we recently published lead by Iraki (also a co-author on this paper) on offseason nutrition recommendations for bodybuilders.
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