Endurance sports nutrition: state of the art in 2019 with prof. John Hawley | EP#181
Professor John Hawley is one of the leading researchers in the world on sports nutrition, the interaction between exercise and diet on fat and carbohydrate regulation, and the cellular and molecular basis of endurance sports adaptations. He gives us a complete update on what we actually know as of today about endurance sports nutrition, and where evidence is still lacking.
Discuss this episode!
- Let's discuss this episode and the topic in general. Post any comments or questions in the comments at the bottom of the shownotes. Join the discussion here!
In this Episode you'll learn about:
- Nailing the basics of endurance sports nutrition - what's most important top consider and get right?
- Getting clear on commonly misunderstood terminology in the field of nutrition.
- Beyond the basics: the impact on endurance performance of manipulating carbohydrate availability, nutrition periodisation, and day to day diet.
- Fat, carbs, and their impact on inflammation and recovery, insulin response, and body composition.
- How do elite endurance athletes actually eat?
- Common myths about and mistakes amateur athletes make with nutrition.
Past nutrition episodes
- I started out doing economics as my first degree, but found I didn't have too much passion for it and switched to exercise physiology.
- I did my undergraduate training at Loughborough in the UK when there were good runners around: Sebastian Coe, and others.
- I then went over to Dave Costas lab in the USA and did my Masters there.
- I then did my PhD and post doctoral training at the University of Cape Town under Tim Noakes.
- I'm now the director of the Mary MacKilop Institute of Health Research in Melbourne, Australia.
It's the exercise and nutrition research group which is a large group.
We study exercise and nutrition and their interactions, including their effects on training and on health.
- We don't delve into pharmacological drugs so every study has a nutrition or exercise perspective.
Carbohydrates, fats and proteins in health and wellness
- Fat has probably been the most misunderstood.
The role of fat in the athletes diet has been overplayed. There is a role for it, both in athletes and inactive people, but it is a permissable role.
- There has been a lot of bad press about carbohydrates, but it is an essential fuel if you're an endurance athlete or partaking in high intensity sports.
The higher intensity the exercise, the more you burn carbohydrate based fuels. This makes it absolutely essential.
- Protein has come back into vogue, and there are many great labs (Luk van Loon in Maastrict, Stuart Philips in Canada) who have done a lot of work on the various types of protein for building muscle and cytopenia.
- I think a lot of people can stand to take in a bit more protein and drop some fat.
- The bottom line is that fat, per gram, stores twice as much energy.
If you think of carbohydrate or protein, you get about 4 kilocalories per gram; with fat you get around 9.
- For people who are predisposed to type 2 diabetes, carbohydrates can be dangerous because of the massive fluctuations of glucose that occur.
If you put that type of individual on a high carbohydrate diet, you're setting them up for failure in the long run.
- Overall, if you're looking at the 'healthy' population (although unfortunately most of the population aren't healthy), then I don't think the recommendations for the proportion of fuels we take in has changed dramatically.
- One thing that has changed is portion sizes.
The macronutrient composition of diets has not changed over 40-50 years, but the quantity of food and therefore the quantity of energy and calories is 2-3 fold greater.
Nutrition for endurance athletes
- Endurance athletes would define any event of a continuous nature lasting longer than around 30 minutes.
If you look at those events, the energy required to combust them is mainly coming from carbohydrates.
- Almost all sporting events depend on carbohydrate and have some endurance component - even team sports.
- As far as the 80/20 rule, for the endurance athlete the diet should be carbohydrate based.
- The concept of what a high carb or low carb diet is massively confused in the media.
People often think a high carb diet is eating as much starchy food (e.g. potatoes, bread, rice, pasta) as you can in a day, which isn't true at all.
- Nutrition is great, but nothing replaces training - we eat to support our training.
Training is the 80, and nutrition is the 20 on top.
- Regarding nutrition products I confer to my wife (Louise Burke), who is head of sports nutrition at the Australian Institute of Sport.
The emphasis there at the last dozen years or so has been on food, rather than supplements, gels etc.
A lot of the products don't have vitamins, minerals, fibre or other things that are essential to the diet.
- Sometimes I think we've lost track of normal food and what athletes should eat.
- If you're travelling in a remote place, or aren't able to sit down for breakfast after a training session, then some of the bars and gels are very god.
However, they shouldn't be the basis of an athletes diet.
- Food should be the priority, and the gels/bars/sports drinks should be the icing on the cake.
- In terms of fuelling during training, it depends on the purpose of the session.
If it's an easy Saturday night, where the output is low to moderate and you want to burn fat, you want to abstain from carbs as long as possible.
However, if you want the ride to be at race pace then you'll want to supplement.
- Nutrition should be tailored to the session, not the other way around.
- Any time that you take in carbohydrate, your fat oxidation will immediately be suppressed.
- Even a pre-training meal can blunt the breakdown of fat and can impair fat oxidation for several hours.
- Subtle changes in nutritional status can massively alter the fuel balance of a training session.
Looking at work from George Brook's lab by Brian Bergman can help with this question.
- The absolute intensity of exercise determines the total fuel bill.
- The relative intensity (how hard it is for you, percentage of maximal heart rate, rate of perceived exertion, percentage of VO2max etc) determines the fuel mix.
200 watts for a world class cyclist may mean burning exclusively fat, whereas 200 watts for a novice would be close to max and would be burning carbs.
- On top of that, nutritional status can shift the curve from the right to the left as well.
Shifting the nutritional curve
- There was data published by Louise Burke and colleagues in the Journal of Physiology a couple of years ago, with athletes who were keto-adapted, meaning they'd been habitually on a high fat diet.
- When the subjects are on a normal training diet (predominantly high in carbs) at a fixed sub-maximal work rate (50km race pace in this case) they burnt 0.5-0.6g fat/minute.
- When they were shifted to a high fat diet and carbs were removed, that number doubled.
In some individual athletes it was more than double the initial rate of fat oxidisation in a chronic state.
- The acute state would be less than that, but in a 4 hour ride if you change fat oxidation from 0.3 to 0.6g it will be quite substantial.
- It's probably 20-30% in the acute case, but in someone who has had a high fat diet for weeks you can double the rate of fat oxidisation.
- Any time you are doing a hard endurance workout the message is still clear: carbohydrate before, during and post is a good thing.
- There is now ample evidence that good quality protein sources in the golden window (1-3 hours after exercise), adds to the muscle stimulated increase in protein synthesis.
Contraction alone of the resistance type would increase protein synthesis, but when you add protein ingestion it's almost a double of the rate.
- Protein for endurance athletes has been underestimated, and considering muscle damage from sports like running it may be important to pay more attention to protein intake.
- You need to up the protein RDA: 0.8g doesn't cut it for an endurance athlete, you probably need 1.2g of high quality protein for each kg of body mass.
- If you look at the position statements from the IAAF and IAC you'll see that we now realise endurance athletes need more protein than we originally thought.
- If you're doing more than 15 hours a week, you're a pretty serious athlete so your nutrition is more important.
- In terms of protein timing, we have looked at protein distribution throughout a day.
We were looking at the distribution through an exercise bout and for twelve hours after - it was an 18 hour study.
We showed clearly that by spreading the protein in small 20-25g feedings through the day was much more effective than giving exactly the same amount of protein in two big portions, or just trickling very small amounts in (10g every 30-40 minutes).
We took the recommendations for strength trained athletes (20-25g post exercise) and we just kept doing that throughout the day.
If you looked at how much protein synthesis took place, the regular feedings were much more beneficial.
- You need to make good food selections throughout the day.
- Athletes are burning so many calories each day that they generally don't need to worry about when they are eating.
- If someone is recreationally trained, the need to get to carbohydrate immediately after a session isn't as much of an issue as they have more time to replenish their stores before the next session.
- Once you get into 8-10 hours a week of training, it becomes more important.
- There is no strict rule as what suits one athlete may not suit another.
- Anecdotally, females prefer smaller regular meals, whereas males can get away with eating 2-3 big meals per day.
- However it depends on your sport - you may not want a big meal before running for example.
- There is a huge media and scientific push at the moment for time restricted eating.
The studies that have been done (mostly in America) suggest the average window of eating is 12-14 hours a day.
What dieticians are saying is that is you restrict your window of eating to 8-10 hours day, without any attention to the energy you're taking in or the composition of the food, there are health benefits and potentially weight loss.
This can be done by shifting your breakfast to a couple of hours later, making your eating window 8-9 hours.
- The studies that are trickling out suggest that for the 'unhealthy' population, this may be a more practical way of dieting.
- Athletes probably don't need to bother because for the most part, especially in females, getting enough energy in is the issue.
- Our paper recently published in the International Journal of Sports Nutrition and Exercise Metabolism is a helpful read here.
- We became aware of the fact that athletes get very confused with the terminology.
- One of the biggest buzz things going around at the moment is the ketogenic diet.
- Everyone wants a quick fix - whether you're an athlete trying to get faster, or someone doing it for health and weight loss.
- When I talk to athletes and they say they're on the ketogenic diet, I often ask about their breakfast and they'll tell me they had yoghurt and fruit.
They've probably had about 50g of carbs already.
The definition of a ketogenic diet is that only 5% of your intake should come from carbs.
In practical terms, that's around 50g.
- It's impossibly hard to have less than 50g of carbs a day unless you're seeing a dietician or a sports nutritionist.
- To get an athlete in a ketogenic state is not difficult, you just need to drop the carbs to very low levels (as low as 25g a day).
There are many trade offs - they are irritable, they can't train as hard, their sleep isn't as good.
- When we do studies on this the teams feed the athletes for 3-4 weeks and know everything they intake.
Often athletes may think they are on a ketogenic diet but they often are not.
- It's almost impossible to get an athlete to do this for longer than 3 weeks because they feel so bad.
It works for a very small percentage of athletes who are doing ultra endurance events that last several days or longer.
I don't feel it has a place in Olympic distance competitions.
- We started the studies on high fat years ago - and we went in with a hypothesis of no difference - but we just did not find that it worked!
- Ketogenic diets are different from low carbohydrate diets.
- People often also think a high carb diet means eating as much carbohydrate as you can, which is not true at all.
Depending on the athlete/training session, a high carb diet may be 6-7g/kg body mass.
A low carb diet, probably less than 3g/kg body mass.
- The 'train low' idea is another one - how low does your muscle glycogen have to be to train low and get some of the benefits that periodised nutrition can give.
It's hard to put a number of it but I would say 50% of whatever your resting glycogen is.
There is obviously a threshold of glycogen in the muscle that is obligatory to do work in the first place.
- The early studies were done when athletes trained twice a day, doing a normal session in the morning then deliberately with-holding carbs before the second session.
In the lab studies we've performed we hit upon sessions that depleted 50% glycogen, so that's where I'm getting that number from.
40% may be better, but you need 50% minimum.
- Quantifying this is difficult. If you go on the fact that you generally take in 400g, which is 1600 kilocalories of carbs, you are probably going to be pretty high in glycogen for the first session.
We found that when athletes train with lowered muscle glycogen, on average their power outputs or speed are reduced by 7-8%.
However the hormonal and metabolic milieu, and the adaptations in the muscle, are greater than when you do all your sessions with high glycogen.
- When we did our first studies we did two sessions in a day, but the second session was compromised so we now do train high sleep low.
- We found that if we give athletes their normal diet and we get them to train with high glycogen stores in the later afternoon or evening.
As they have high stores the session is a high intensity one and is not compromised by a lack of glycogen.
We then deliberately with hold carbohydrate foods and put them to bed so they sleep low - in a low carbohydrate state.
The athlete then comes back in the morning fasted, ready for a session. They have the benefit of a high intensity session the night before and in the morning they do a long easy ride or run for 2-3 hours.
Their fat oxidation rates go through the roof.
- By sequencing the order of training and nutrition, we've got the best of both worlds.
The high intensity training session is not compromised, the adaptations happen at a better rate at night, and the next morning they burn as much fat as the muscle can possibly oxidise.
- This came through trial and error but mainly through athlete feedback.
- We now have a robust and scientific model which we think is a good compromise.
- Train low should not be done every day of the week.
We did it twice a week or three times a week at most.
- In the 4-6 weeks before an important race it can be beneficial to do more train low sessions in in the morning then.
- If you have an injured athlete, it may be particularly beneficial to do some of these sessions to accelerate the training adaptation.
- We generally use these sessions before major competition, stopping them 2-3 weeks out from the race.
- No matter what your sport, you don't do the same workout every day and so the same is true for nutrition.
- You tailor your nutrition for your training - there are days when you need less carbs (easy day), and when you may need more protein (resistance training).
- Nutrition is not one size fits all.
- The concept of periodisation for nutrition is about adjusting nutrition to the demands of the training, and the outcomes you are hoping to achieve.
- For the endurance athlete, there won't be a massive variation from competitive season to off-season.
The carbohydrate intake may increase as the workouts get more intense closer to a big race, but on the whole the athletes diet is quite stable across the year.
- Across a week, there may be deliberate attempts to withhold carbohydrate to enhance fat oxidation.
Over the general course of a year, it will remain relatively stable.
- Generally athletes will consume 70% of their energy intake from carbs throughout the year.
It may drop to 55% on some occasions, and may go as high as 80% in others.
- Some studies misuse the term and describe periods of dramatic diet changes for 3-4 weeks, such as a reduction in cards,
- When you're not training 20 hours a week and you're in the off season, you probably don't change the composition in your diet that much in terms of percentages, you just lower the energy intake.
- In the microcycles there will be subtle changes, but they really are subtle.
- The swifter, higher, stronger paper we published describes what athletes eat.
It was published in Science and was included on the cover of the journal which was a massive breakthrough for sports nutrition.
- We discussed in the article some of the practices of elite athletes but I think these practices do apply to the recreational athlete.
- If you're burning more calories, you're eating more, but the composition doesn't necessarily change - the principles remain the same.
- The more you're training the more you may need to rely on sports nutrition drinks, bars and gels.
- The elite athlete is different - physiologically they're different but the fuels needed to combust their muscles is the same, it's just the degree the training demands dictate.
- If you look at the Kenyan athletes, their carbohydrate dependent, and they are lacking in a lot of the saturated fats you see in Western diets.
They're the best long distance runners. They're probably not great just because of their diet but it puts the icing on the cake.
- Generally if you're over 50kg now you're now going to be at the startline of a major marathon.
- For African athletes their diet is different as they have a lot of meal and maize which looks fairly unpalatable.
For the general Western diet the stables are still the stables - bread, yoghurt, pasta, potatoes.
- Nutrition tends to go in waves, at the moment there's a push in some articles that eggs are bad for you. There's also been a swing against dairy.
Things come and go, but the enduring feature is the carbs are carbs - no matter how you get them in the muscle sees them the same and they'll re-synthesize them to glycogen.
- Food differs across countries but most people know what high quality carbs are, and know to stay away from saturated fats.
Protein in both animal and vegetable form is pretty good.
- You eat what is practical and available for where you are in the world.
Common mistakes endurance athletes make in their nutrition
- For someone who is training 20+ hours a week, particularly females, the concept of taking enough energy a week is missed.
- We see a whole myriad of injuries - stress fractures, compromised immune system etc when you have low energy availability.
This basically means you're not taking in enough food to match the demands of daily living and training.
- Another common mistake is trying nutritional strategies in a race without trialling them in a training situation.
Try everything in training before you do it in racing!! It sounds simple but it's forgotten a lot of the time.
- When athletes deliberately avoid certain foods, it's always a red flag for me, it's a form of disordered eating sometimes.
Any time you abstain from something, it can be dangerous.
Low carb for reducing inflammation
- You often hear in the media that low carb diets are good for reducing inflammation and supporting recovery, however this doesn't stack up scientifically.
There are studies done years ago by Dr Mark Fibrio which show that one of the inflammatory cytokines (IL6) is massively elevated in the normal state, but if you drink carbohydrate during exercise it suppresses that.
This is the exact opposite to what the media are saying!
- Inflammation to some degree is part of the important adaptive process, but too much of anything is bad.
Too much inflammation is a prerequisite for some metabolic diseases, but you need some of it to have an adaptation.
Insulin and blood glucose responses
- Insulin and blood glucose is another thing that is overplayed in the media.
- When you ingest a meal which has carbs, fats, protein and other micronutrients, the first thing that happens is a glucose response.
Your glucose goes up, and the pancreas secretes the hormone insulin which then takes that glucose into insulin sensitive tissues.
- Skeletal muscle accounts for 70-80% of the glucose disposal.
- Athletes are highly insulin sensitive, which means that their muscle sees glucose and soaks it up like a sponge.
- There are two ways of disposing of glucose after a meal: the hormone insulin, or through contraction.
You can contract a muscle and have an increased rate of glucose uptake.
- The athlete is in a continuous state of contraction - they've either just trained or are going to train.
In the case of an athlete, the argument that you shouldn't take in carbs because you'll become insulin resistant and develop diabetes is just ridiculous.
- On the other hand, a type 2 diabetic obviously shouldn't have a large carbohydrate meal and go and exercise after because their transport system to move glucose into their muscle is impaired.
Low carb diets for reducing body fat composition
- Energy restricted diets which have low carbohydrates, in the short term you will lose weight on the scale.
That is weight though, that is not body composition.
- You lose that because when carbohydrate is stored in the body it stores 2-3g of water with it.
No carbohydrate = no water.
Withhold carbohydrate means you lose weight, but you'll probably feel crappy in the morning.
- The general population is too hung up with weight. Body composition is a better prediction of health outcomes.
In other words, the ratio of your muscle mass to your fat mass.
- We tend to DEXA scan athletes for body composition, rather than ever using weight.
- Most energy restricted diets in the long term (6-12 month follow up) are ridiculously unsuccessful.
- This is why time-restricted eating may be a far better method for long term success.
- Most of the studies in the medical literature only measure weight of the subject, not the body composition, but the scales measure mass and that's it.
- Everyone wants the highest muscle mass by their big race and the lowest fat mass.
The only exception would be sumo wrestling!
Rapid fire questions
- What is your favourite book, blog or resource related to your field of expertise?
- I follow Twitter and find some of the discussions very useful. However, remember it's not science!
- Follow the people who are actually doing the research and have a good scientific background.
- What is a personal habit that has helped you achieve success?
- In an average year I miss about 7-8 days of training and that is usually when I'm on the road travelling. The discipline of being an athlete and always making that time in the day is really important - some of my best ideas for studies have come during training sessions.
- Regular exercise everyday keeps me sane, keeps me fit and helps generate some great ideas.
- What do you wish you had known or some differently at some point during your career?
- I wish I'd have know when I was a competitive 400m athlete that I didn't need to do long slow runs and done 50-60 miles a week! I would have cross trained more, and got a loss less injured than I did! I would also do a lot more resistance training for muscle mass, but overall I think I'd train less.
- Rest judiciously, generally people are overtrained.
Links, resources and contact
Links and resources mentioned
Connect with John Hawley
Connect with host Mikael Eriksson
Hi! I'm your host Mikael,
I am a full-time triathlon coach and an ambitious age-group triathlete. My goal is podium at the Finnish national championships within the next few years.
I first started the website Scientific Triathlon in autumn 2015 as a passion project to share my learnings with a larger triathlon audience. Later on, in early 2017 I started the podcast That Triathlon Show.
I sincerely want you to contact me to
- Send me feedback
- Give constructive criticism
- Request topics and guests for the podcast
- Send me your triathlon-related questions
- Tell me that you've rated and reviewed That Triathlon Show so I can give you a shout-out on the show and tell you how much it means to me!