Guest Interview: Casey Thomas, Esports Performance Nutrition Specialist

Welcome Casey Thomas, Nutrition Specialist and Registered Dietitian. Casey works with a lot of professional esports players. I always look with a keen eye on innovation in esports to translate to chess, so I’m always interested in Casey’s presentations and content. He kindly agreed to answer a few questions on nutrition. His answers are incredibly detailed and extremely informative. Many thanks Casey!

Please tell us a little about yourself and how you came to work in the field.

I took a bit of a circuitous route to get to where I am now. My parents wanted me to be a doctor so I was on a premed route initially. The brain always fascinated me - and so for my undergrad, I chose to be a Neurobiology major. After shadowing some doctors, I realized I definitely did NOT want to continue that path.
I was still a nerd for brain science, and I wanted to be at the forefront of that discovery process, so I entered the world of clinical research in the private sector. Specifically, we were looking at the impacts of various supplements and pharmaceuticals and their impacts on the brain in both healthy and clinical populations.
Small sidebar: There is an interesting observation in the sports world - you can predict the next round of performance-enhancing substance use by keeping a close eye on the medical literature. For example, EPO doping in endurance sports followed learning of its use to help those with malfunctioning kidneys.
My first exposure to high-level athletes came from savvy athletes looking to see if there was anything we were researching that may be performance-enhancing and wasn’t yet being tested for or banned in the sports world. I started working with some of these athletes on the side as part of my private practice and was hooked. The closest career that would have me working with these individuals in a similar capacity was that of a dietitian, so I quit my job and went back to school.
After graduation, I started working with UCLA Athletics and oversaw their performance nutrition program. It was a fun experience, and I got to work with some really high-caliber athletes (I also took home a few championship rings). One of my claims to fame at UCLA was leveraging nutrition and supplement strategies to enhance measures of cognitive performance - for example, hand-eye coordination and reaction time in baseball, or shooting accuracy in basketball, etc.
Anyway, the UCLA esports program saw what I was doing and asked if I could support them in a similar fashion. Being a gamer myself, I answered yes immediately and started doing what I could for the players. I was also very close with the performance specialist (Haylesh Patel, the GOAT) for the esports program at UCI (where I did my undergrad), who also had me come in to provide some nutrition support for them at about the same time.
At that time, esports had 0 nutrition professionals working in the space, and I decided to make a website (gamerdiet.gg - horribly outdated, if someone wants to help me refresh it, please reach out) to provide some evidence-backed nutrition guidance to this population. At about the same time, COVID started, and my job with UCLA became very unfun since I wasn’t allowed to work with the athletes directly anymore. Also at about the same time, 1-HP reached out and asked if I could oversee their esports nutrition program.
My mind was set, and I left UCLA to pursue private practice and support 1-HP. Today, I maintain my private practice and oversee the esports nutrition program with 1-HP. I also teach at several universities, am a published scientific author, and still regularly engage in scientific peer review.

What is your role in the esports world?

My main role is that of a performance dietitian. Simply put, I tell people what to eat in order to perform better.
Depending on the budget of the players/team/organization, the level of integration will vary quite substantially.
With a lower budget, I may do a few educational seminars to help optimize whatever is the weakest link (for example, supplements, pre-game nutrition, etc.).
With a higher budget, I may be directly responsible for ordering all food for the individual/team. If there is a chef involved, I may curate menus with them.
Ideally, I’d do regular 1:1s with all of the athletes and do a detailed assessment to determine exactly what each individual needs to see the highest return for their nutrition efforts. I’d then come up with nutrition, supplement, and hydration plans for them - and then have it directly provided to them without any effort on their end.
Sometimes, I’ll do team bonding exercises like cooking classes. Sometimes, I’ll work with the team when they’re travelling. It depends a bit on the needs of the team.
On the big picture side of things, I try to create evidence-based content on this topic, though I just do it on the side of my main jobs so my activity level varies depending on my availability. I have put together a nutrition basics course (see EHPI) targeted at coaches and other performance specialists who work in this field and want to learn best nutrition practices for this population. I regularly speak at conferences and try to promote the need for nutrition professionals in esports. I’m being featured in an upcoming textbook discussing this emerging opportunity for sports dietitians.
On the fun side, I play several different games casually with friends. I usually like following the professional scene and will enjoy going to big events or setting up viewing parties.

Image credit EHPI

Do you play chess?

I learned to play in elementary school when I was maybe 7 or 8 years old. I got more interested in middle school and joined the chess club. I had lots of fun doing it but wasn’t too good. It was mainly a way for me to hang out with friends.
In high school, I started playing more and reading some books to help me improve. I found some online websites to play against other people (I’m dating myself, but playing online was a relatively new phenomenon), and decided to try my luck.
I got absolutely obliterated.
Outside of my small bubble of people I had been playing with, where I was mid-tier, I quickly came to realize I was ranked as one of the worst among people who were playing online.
I was young, dumb, and easily discouraged. I am ashamed to admit that I rage quit ‘serious’ chess on the spot and have not played it with any degree of competitiveness since then. I thoroughly enjoy it to this day, and do play casually, but there are so many layers of nuance to the game that I simply have not had the time to dedicate any serious study into it. I have enormous respect for those who have a deep understanding of the game itself - and have worked with some chess grandmasters myself - but I have chosen to put my serious mental efforts into my own craft.

People are endlessly confused about nutrition, possibly because of social media. Why is it made in such a confusing topic?

This is a loaded question that can be answered in several different ways. I’ll list what I think are the top 3 reasons -
First: The biggest issue is that there are no nutrition professionals in the space. When you look at traditional dietetics, approximately 70% go work clinical, 20% go work food science, and 10% go work in “other” (private practice, sports, etc.). There are only a few dietitians involved in areas that rely predominantly on cognition (I can probably count it on my hands, and 2 of those are myself and the RD I hired to support me).
What does this mean? There’s a huge void. This has left the pseudo-scientists, quacks, supplement companies, and anyone looking to make a quick dollar to flood the space with misinformation and dominate it.
There is no way a handful of people can stop the tide against traditional media and social media outlets. And whenever someone DOES submit a contrary opinion, it just adds to the noise. People are left thinking, “if the professionals can’t agree, then I’ll just trust the big guy in the gym / my favorite influencer”. And honestly, I don’t blame them for thinking that way. Short of having spent years studying nutrition science, there’s really no way for the general public to know what information is based on good evidence or not.
Second: Most people equate confidence with strength of evidence. If someone says, “this diet has been CONCLUSIVELY PROVEN to help you shred fat”, people think they must be standing on some good evidence. Scientists won’t even use the word “proven” with well-established phenomenon like gravity. So with nutrition science, the smart people will always be saying things like “this MAY help”, and “it depends”. To a lay person, they’ll think the scientist is unsure and/or standing on weak evidence, when in reality the scientist is trying to demonstrate academic honesty.
And finally third: Most competing claims are completely true! Let me give you an example with a hypothetical person named Joe. Joe currently does not care about his health at all. He eats fast food for most of his meals, is mostly sedentary, drinks alcohol regularly, sleeps inconsistently, is lonely, and stressed. He decides to get his sh*t together. He sees his favorite influencer advocating for diet X and decides to give it a go. Joe starts up with the new diet and drastically minimizes consumption of the fast food and alcohol he was previously ingesting. But why stop there? He’s on a health kick, so he gets a gym membership, starts getting out more, and makes some gym friends who help keep him accountable. He’s on a regular routine now and starts sleeping better.
A few months go by and Joe is a whole new person - he’s feeling physically and emotionally better, getting into shape, and has a lot more energy. You ask him how he did it and he answers, “Diet X was a game changer for me”.
The lesson here is that people who tend to start diets, also start other healthful practices, which are most definitely contributing to the improvements. And even when you account for all of these confounding variables, Diet X is still a winner! Why? Because you compared it to the trash the individual was consuming before. This is the biggest issue in nutrition literature - ANY diet is going to have superior results to the “standard” diet.
This process leads to diehard fans of diets, because the individuals saw very real results moving from their trash pattern to a healthful pattern. Most people do not want to then move to a state of similar unhealthfulness to re-test everything again with a different diet to see if Diet Y has superior results to Diet X. They just advocate for Diet X (it worked!) and keep doing what they’re doing.

When you work with esports players, how often do you focus on getting basics right and supporting their physical training and how often do you try to ‘optimize’ for cognitive function? Or can you achieve both at the same time?

Smart question. You are right - the basics MUST come first. The basics will get you 80% the way there. There is not one single strategy, ‘hack’, diet, or supplement, that can overcome a deficit in a fundamental area.
Unfortunately, the majority of players I work with need to work on establishing that healthful baseline. I can still discuss the benefits to cognition within the context of fundamentals, but it’s somewhat rare for me to jump right into higher level strategies.
On average, there may be 1-2 players per esports team who is already truly putting in efforts to their nutrition before I start working with them (usually for body composition and aesthetic reasons). On average, they tend to be older individuals who have come to start to appreciate the impacts of nutrition.
The common argument I hear is, “I made it to rank 1 on the ladder without taking nutrition seriously, why do I need to start?”. This is a similar bias to what I was discussing previously - they have failed to extend their thoughts to a scenario in which they HAD taken their nutrition seriously. If they had, they could have hit rank 1 quicker/easier, or been at an even better skill level currently, but it’s hard to acknowledge or appreciate it without having experienced it.
I will add that because there is such a vested interest in supplements, I almost always am creating individualized stacks for the players on a team. However, I start modestly, and use supplements to first shore up likely deficiencies in the diet – for example, I’ll run a nutrition analysis on their intake and find them to be low in a particular vitamin/mineral, at which point I’ll give them a targeted single ingredient supplement for that particular deficiency. I won’t reach for a generic multivitamin. After I’ve used the supplements to balance their diet, I’ll begin to have conversations about using ergogenic supplements. The most common is to create customized caffeine protocols for scrim days and match days.
You often read that people have large individual differences and that nutrition cannot be a one-size-fits-most. How big are individual differences between people?
It’s true, unfortunately. My job wouldn’t exist if there was a truly proven best diet. If it existed, everyone would be doing it and that would be the end of the story. I would have chosen a different career path.
If individual differences aren’t accounted for, you can at best assume a normal distribution pattern. Approximately 2⁄3 will respond how you expect them to, and 1⁄3 will be hyper responders or negative responders.
In my experience, and depending on what metrics you look at, this is generous. More realistically, I would say 1⁄3 respond exactly as expected, 1⁄3 have a null response, and 1⁄3 have the opposite response.
It’s honestly more likely that copying a diet from your favorite influencer WON’T work for you.
With more information, the more accurate we can make our first guess. But I want to really make one point crystal clear - all of this is moot. At the end of the day, the proof is in the pudding. We can never be 100% sure, and observed results will quickly point us in the right direction. If our best first guess says you need 3,000 kcals / day to gain weight and build muscle, and you follow it diligently but are continuously losing weight, then who cares that the prescription was 3,000? If your goal is to gain weight, the recommendation is wrong. Add calories!

I did write an article on nutrition for chess players The game day chess nutrition guide, in which I tried to be as evidence based as possible. In the process I realised there are a lot of things we don't really know! What are things I was right to stress and things were I got mistaken? I'll gladly update the article :)

First, thank you for this! This is honestly the kind of information I wish was being disseminated - honest efforts at providing evidence-backed guidance to this population. No ulterior motives.
I don’t have too many “bad” things to say about this article, though I will point out a few areas I disagree with -

1. Your GI examples are poor - most lists will put bananas at a higher GI than chocolate. Bananas tend to rank on the high end of ‘low’ or low end of ‘moderate’. Chocolate can range from very low to moderate, depending on ingredients.
   1. My point 1 is moot. GI is a useless tool. I wouldn’t have included it in the article to begin with. The only population it may be useful for is diabetics. Normal individuals rarely eat carbs in isolation, they have it paired with other things. Depending on the ‘other’ thing, it will completely alter the blood glucose (BG) response. For example, plain white rice has a high GI, but white rice with beans has the GI of beans (fairly low). But who cares about the BG response anyway? Normal, healthy individuals are perfectly capable of managing large glycemic loads. If you can’t, then you are metabolically inflexible and have bigger health concerns that need attention.
2. Regarding hydration - you can have cognitive impairments from being overhydrated. You can think of overhydration as a situation in which you have diluted your blood. I would have made it clear that urine shouldn’t be coming out crystal clear like water, it should be light yellow.
3. You mention that postprandial somnolence is not related to drops in cerebral blood flow. While cerebral blood flow is tightly regulated, we do have several lines of evidence pointing to dips in cerebral blood flow postprandially. For example:
   1. Dips after fat consumption:
      1. https://pubmed.ncbi.nlm.nih.gov/22572644/
      2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10534483/#B23-nutrients-15-03969
   2. Dips after lunch when breakfast is skipped:
      1. https://pubmed.ncbi.nlm.nih.gov/30515951/
   3. There are definitely studies showing null changes postprandially, but I’ve not come across studies that show eating a large meal leads to increases in cerebral blood flow. As you say, the take-home is simply to avoid big meals right before a large cognitive load.

You do a lot right in the article, and I’ll simply say the rest is pretty solid! I think my favorite part is that you provide practical advice people can go home with. Everyone should go check it out.

Photo by Manki Kim on Unsplash

How much do we know in terms of optimising diet specifically for cognitive function?

One thing to understand is where the money goes for scientific research. Funding for research follows topics that have a possible return on investment. Big picture, performance nutrition at large is not well researched. The money is in clinical nutrition, because unhealthy people have more pressing issues and companies can make more money supporting them.
Sports are a nice form of entertainment, but games with players playing marginally better will generate next to no revenue compared to something like widespread adoption of a new standard of care for diabetes management.
We’re starting to see some attention given to this field in the realm of cognitive workers, with a lens on metrics like ‘fewer sick days taken’ across a year. We’ve also obtained a tremendous amount of data in relation to nutrition and cognitive function in elderly, both with and without some form of cognitive impairment (like Alzheimer’s Disease).
When we look at data in healthy young, the data are sparse.
Hope is not lost though. If you’re willing to do some digging, you can pull up a pretty comprehensive picture of how the brain is impacted by nutrition. If you look at how the brain operates and uses the different nutrients at a basic, biochemical level, you can make guesses at how deficiency/sufficiency/surplus in one nutrient or another impacts a process. Then, you can look at some of the studies that exist. You’ll need to keep an open mind and be willing to look at parallel fields to what you want. For example, you might look at the tactical setting for things like shooting accuracy, or look at students for memory.
In any case, I’ll say it’s a bit of an unfair question to ask because you’re essentially asking me to summarize the entirety of this field, when we have data going back thousands of years, but I’ll give you a teaser of some things that you can go look into yourself.
We know that certain dietary patterns are great for long-term brain health – for example, the Mediterranean Diet is consistently ranked #1 for this.
We know that as little as a 1% dehydration will significantly impair all cognitive metrics we look at.
We know there are certain nutrients that do cool things for the brain, like enhance blood flow to it (see berries), improve the raw architecture (see healthy fats), or increase the amount of molecules that support brain function (like BDNF, see fruits/vegetables and omega-3s).
We know certain compounds can make you acutely dumber (see processed fats and alcohol).
We know certain supplements can be used ergogenically (see caffeine).
We even know that people respond quite differently to different dietary approaches and compounds (see genetics, epigenetics, and gut microbiome).
I’ll stop there, but I’ll say that there’s a lot more to be learned for sure, but I think the picture is already clear enough to make recommendations.

Let's talk about in-game nutrition. A chess game can take up to seven hours. A prevalent belief is to keep your blood sugar constant and avoid spikes, but I couldn't find any evidence to back that claim. What do you think?

Early on I definitely thought there might be something there for two reasons:

1. In a clinical setting, extreme elevations or depressions in blood sugar lead to all sorts of abnormalities
2. In a non-clinical setting, we have seen glucose be used as an ergogenic aid for all sorts of performance measures

When you dig into it, you can’t really find any data that suggests spikes cause problems in normal, healthy individuals. The human body is resilient and is expected to be able to manage large glycemic loads without too many issues.
The final nail in the coffin came from a recent study by a friend of mine in an esports population (young, healthy, normal individuals). They found no changes in any of the cognitive metrics despite one group having a rapid rise and fall in blood sugar.
https://www.ijesports.org/article/47/html
There are definitely food recommendations that can be made that may have an indirect link to blood sugar, but I think this study really showed that blood sugar per se is not going to dictate cognitive performance outcomes.

I can't resist asking for practical advice. How do you think a player should eat during a 7-hour chess game?

Generally, I like to think about 4 different time blocks - the day before a match, day-of before the match, during the match, and after the match. I’ll answer your question about the ‘during’ time period and make the assumption the other blocks are taken care of.
First off, the exact eating times and amounts will vary a bit depending on when the matches are played, how long the breaks are, etc., but I’ll make some general guidelines here.
If you have a longer break (1+ hours), you can have something that looks like a “mini meal”. If you have less time, you’ll be looking at snacks.
In general, across a 7-hour block, and assuming you took care of your pre-match nutrition, and that you have at least an hour, you would be fine with 1x mini meal roughly halfway through. If it’s been a while since you ate, you’ll probably be needing 2x feeds evenly spaced (either 2x snacks, or 1x mini meal + 1x snack if time allows).
For food choices, you will want to minimize the amount of fat and fiber consumed. These are the two hardest nutrients to digest, and we don’t want to risk any stomach discomfort when digestion is already impaired due to higher levels of stress hormones on a match day. You should also never try any new foods on match day. Only use safe foods you are 100% certain your body is familiar with.
We give priority to easy-to-digest carbs and lean sources of protein. For a mini meal, for carbs, you’ll be looking at things like white rice, white bread, plain pasta, etc. For protein, you’ll choose lean options like chicken breast, turkey, low-fat yogurts, egg whites, etc. Some sample mini meal examples would be a small portion of sushi, half a simple sandwich, a small plate of grilled chicken pasta with marinara, etc.
For snacks, you can look at things like saltine crackers, rice cakes, and pretzels. These will be easy on the stomach, provide glucose for the brain, and encourage thirst with their salt content.
You could also experiment with some performance snacks. The best for this scenario would be berries, which have been shown to provide sustained attention across longer durations like this scenario. Some other potentially ergogenic options would be oranges, for pattern recognition, or a cup of coffee or tea to lessen fatigue.
What new results from esports nutrition research can we expect in the next couple of years?
There are now a couple of labs beginning to investigate the topic of esports nutrition, which is exciting, but I don’t think there will be anything too groundbreaking in the next few years. Most of the research that needs to happen before the interesting questions can be answered are simple repeats of studies done in different populations (like traditional athletes). Once we’ve checked all of our assumptions and have the foundation secured, we can move into the more interesting strategies. Science is slow but methodical, and esports is coming to the table late.
We also need to work on establishing a consensus on what metrics are actually valuable to esports. From there, we would want to see validation studies demonstrating that improvements in these metrics directly translate to in-game benefits. We saw a blunder historically where those brain training games were marketed as making us smarter, but all they really did was make us good at brain training games, it didn’t translate.
Lastly, biometric data is more readily available to the general population than it ever has been before, and I know some teams are playing around with it in-house. I strongly suspect we will see some more published data of this variety in the next few years.
Alongside all of this more ‘honest’ research, we will also be seeing the results of ongoing industry-funded studies. I’m not against industry funded research per se, though you admittedly do need to be a bit more skeptical, but they usually offer little to the field at large except the immediate result. These studies are constantly ongoing and exhibit large levels of publication bias. If the research is successful, you’ll hear about it. If it’s not, you won’t.
Expect to hear some amazing claims for profitable supplements or dietary programs and products.

What do you think of the very prevalent "supplement" mentality, where people look for a magical supplement but won't have great basics in place?

I hate it.

It’s alluring to think there is a single magic pill that will solve all your problems. However, the key thing to remember about supplements is the definition – it’s meant to work in concert with your diet, not in replacement of your diet. There is not a single supplement that can overcome a fundamental deficit.
It would be so easy if the epitome of health was having fried chicken, candy bars, soda, and popping a pill. Unfortunately, there’s a lot more to nutrition than that. Put another way, trash diet + supplements is grossly inferior to a healthy diet alone. And the data support this.
You can only really get full value out of your supplements if you are already following a healthful eating pattern.
Even then though, there is a significant risk, and we need to be careful. Why? Well, 80% of supplements don’t pass a purity test, and 10-25% contain something that would show up on a drug test! And in the United States (which I’d at least rank in the upper half globally, for rigorousness), 70% of supplement facilities fail to meet minimum operating standards.
This paints a scary picture around the supplement industry, and I could go on, but the main point is this – you need to put in work with your diet, just like how you put in work in your other disciplines. You spend hours in the gym, hours studying, hours on your craft, whatever it is – you put in the work. Do the same with your nutrition. Once you have, then you’ll be well positioned to take advantage of strategic supplements.
Let's be a little speculative. What is a diet or practice that doesn't have a lot of evidence currently but you think might prove superior for cognitive function?
I’m going to answer a slightly different question. I can speculate if you want me to, but I don’t think there would really be a point because people currently resist following practices that DO have strong support already.
For example, garlands of rosemary used to be worn by ancient Greek students with the belief that it helped them academically. We’ve done the research recently and confirmed that rosemary aromas do in fact boost several cognitive metrics.
It seems to me that something is going on and we don’t care as much as we once did.

Photo by Manuela Böhm on Unsplash

I did a very basic internet search for “diet and brain health” and came up with a list of the following diets in the first result, “Mediterranean, Nordic, DASH, and MIND diets”. Admittedly, people may be unsure if there is any truth behind the first hit in a search bar, which is a completely valid concern. Tell me this though, how many people do you know who have honestly tried to follow, say, the Mediterranean Diet, for a few weeks/months, and done a pre/post cognitive test to see if it worked for them?
I’d bet 0.
I can say here and now that those diets do have varying levels of supportive evidence, but your mileage may vary depending on what your baseline diet is before transitioning. The only way to know if these diets help you specifically is to test it out and see.
Similarly, we have some supplements that have support in non-cognitive domains, but don’t seem to want to venture out. For example, there’s tremendous data on creatine in traditional sports for cognitive metrics, why hasn’t it migrated to the cognitive sports?
I don’t have a good answer, but we should start with what we know before speculating!

Photo by Jez Timms on Unsplash

What is the question that I should have asked but didn't?

I think the most important thing not asked would be, “what can I do to maximize my learning on non-match days?”
To answer the question, I need to talk a little bit about how learning occurs.
Think about the last time you went and did some strenuous exercise. Are you stronger at the immediate conclusion of your exercise?
No.
You are much weaker. You have depleted your muscle fuel and damaged your muscle fibers. The repairing and subsequent adaptation happens in the recovery from exercise. You are only stronger with a suitable recovery process.
In the same way, you are not smarter or better at the immediate end of any difficult cognitive task. You need a stressor to kickstart the process, and then you need to recover from it. In fact, most of the transition of short-term learning to long-term storage occurs in the first sleep after the stressor. It cannot be overstated that the recovery process itself is highly energetic and requires certain chemistry to be carried out optimally.
So, how do we ensure we have all the right components to maximize the adaptive response?
You guessed it...good nutrition. For the first meal after the stressor, be sure to have a full, balanced, healthy meal. If you have to ask if it’s healthy, it’s probably not. It should have a balance of all the macronutrients (carbohydrate/protein/fat) and a high nutrient density (vegetables).
It’s honestly pretty simple, but people have a tendency to want to “relax” and “enjoy” unhealthy food options after big stressors or exhausting days. Don’t do this when your goal is to maximize learning.

Photo by Sam Moghadam Khamseh on Unsplash
Thank you so much Casey for all these answers.
Where can people get in touch with you?
The easiest ways are through X and Discord -
X: caseythomasrd
Discord: Caseythomasrd
You can also check out my website
https://gamerdiet.gg/
(which looks horrible and hasn’t been updated in a couple years), but does have quality content. I am looking to do a refresh on it and start putting some more content there this year. If anyone wants to help me, please let me know, I need it!