What are the key nutrition considerations for a full-distance triathlon?
There is no doubt that adequate training preparation is required to be successful at completing an Ironman. However, having the right amount and type of fuel is equally essential for this preparation and for the race day to be successful. I’ve seen how poor nutrition decisions have ruined races for many athletes wasting all the time, energy and money they invested as part of this preparation, and I don’t want that to be your case. This is why I have decided to put this Ironman Nutrition Guide together with the key nutrition considerations for your full distance triathlon to be successful.
Nutrition for Ironman Training
Before we jump ahead and talk about what you’ll need on race day, it is essential to talk about how you will fuel the preparation and why this is important.
The purpose of training is to trigger physiological adaptations in your body that eventually will translate into better performance. Many people don’t understand that nutrition during training goes beyond eating enough calories. The nutrients in those calories are also critical for those physiological adaptations to occur. Therefore the purpose of food during this stage is for your training to be as efficient as possible.
These are the key considerations so nutrition can support your training.
Now is not the time to go on a new diet or try to lose weight. Restricting your energy intake while your training volume increases will only result in catastrophe. Poor performance, higher risk of illness or injury and lack of energy are only a few of the consequences of not getting sufficient calories.
Getting all essential nutrients
Carbohydrates, protein, fat, vitamins, and minerals are all essential for your body to fulfil its core functions, and they all have a role to play in performance enhancement. This is why beyond looking at calories, it is vital to ensure that your diet is well balanced and varied, so all essential nutrients are present.
Eating at the right time
There are critical moments in your day when nutrition becomes even more important. That is before, during and after training.
You want to ensure that your body has sufficient energy to commence the activity so your body doesn’t need to go under unnecessary stress as part of completing that training session. Carbohydrates are your friends and you will need them at this stage.
Some level of nutrition will likely be required for activities with a duration longer than 90 minutes. The longer the duration and the higher the intensity, the more you will need. This is also the perfect time to try the foods and products you intend to use during your race to get familiar with them and decide which ones work better for you.
The nutrients you consume after your training go straight to where your body needs them the most to stimulate the post-training recovery and start working on those adaptations. Both carbohydrates and protein are necessary during this stage. It is also important that you remember to rehydrate, especially if you’ve been training in the heat.
Nutrition for Ironman Racing
Now that the training is covered, it’s time to guide your Ironman nutrition on the day of the event. The goal is to keep your body energised without disturbing your gut. Easier said than done. Here’s what you need to consider.
Fuelling up your tank
Before heading on to race day, you must ensure that your fuel reserves are full. The best way to achieve this is by following a carbohydrate-loading protocol. I know that pasta parties are pretty popular to increase carbohydrate intake before a race. However, eating pasta the night before your race will not be sufficient to fuel up your tank.
For the carb-loading to be effective, you will need to increase your carbohydrate intake at least two days before your race and preferably three. The guidelines suggest an intake of 7-10g of carbohydrate per kg of body weight. This means that if you are a 70kg athlete, you will need to consume between 490 and 700 grams of carbohydrate per day. In case you were wondering, the equivalent is at least 30 slices of bread or 8 cups of rice.
Now, before you go and stuff your mouth with rice or bread (please don’t), here are some ways to help you increase your carbohydrate intake without drastically increasing the volume of food you consume.
- Split your meals into three main meals and three snacks. In each of these, ensure you have high carbohydrate foods (fruits, rice, pasta, bread, wraps, oats, etc.).
- Adding energy-dense options such as sugar, jam, or honey to your meals helps increase your carb intake.
- Drinks are pretty helpful as well. These days, you can have a glass of juice or sugar-sweetened tea and some Gatorade/Powerade throughout the day.
- Try having 1 to 2 extra servings of carbohydrates per meal (i.e. if you usually eat half a cup of rice, try having a full cup).
- Reduce your fat and fibre intake to avoid any stomach upset.
Race day morning meal
This is the moment when you finish topping up your fuel reserves. Overnight your body uses glucose from your liver as energy while you’re sleeping, so the purpose of that meal is to replenish those energy losses. Ideally, you want to have a meal with 1 to 4 grams of carbohydrate per kilogram of body weight one to four hours before your race starts. As a rule of thumb, I like matching them. One gram if eating 1 hour before, two if 2, etc.
Here are some options to guide your nutrition choices on the morning of your Ironman. Always make sure you’ve tried this meal before during training.
Race day nutrition
Alright, now that we know what you eat months and days before the event matters, it’s time to talk about what you will eat and drink on race day. During the race, we want your body to stay energised for as long as possible and keep your gut from suffering.
While moving, your body is using both carbohydrates and fats. Carbohydrates are your primary energy source, and your body is very efficient at using them. However, you can run out of them very quickly. Therefore, even after following a carb-loading, you still need to eat carbs during your race.
The guidelines suggest that for ultra-distance races such as the Ironman, the carbohydrate intake must be between 60-90 grams per hour. This can come from various sources such as sports drinks, energy gels, energy bars, chews or homemade food. For many people, relying on a single energy source (e.g. getting all carbohydrate from gels or drink) doesn’t go well, but some athletes prefer this method. I recommend choosing a baseline sports drink, gels and a solid option and rotating through them with most energy coming from the drink and gels.
To decide which mix works best, you need to try these combinations and quantities ahead of the race. The long training sessions are ideal for doing this. This takes me to the next point.
Dehydration can seriously affect performance and your body’s ability to handle the heat. However, overhydration is equally important and severe, with some athletes developing exercise-associated hyponatraemia due to poor hydration. This is why being aware of your sweat rate ahead of race day will help you plan an adequate hydration strategy that allows you to consume sufficient fluids to keep your dehydration levels within healthy ranges.
Avoiding gut upset
Gut issues during ultra-endurance events are relatively common. Having the proper nutrition strategy and gut adaptation is critical for minimising the risk of this being your case.
Not all foods are created equal, and for those athletes above the 60g per hour intake, looking at the carbohydrate ratio of the food they are consuming is essential to ensure the gut can handle the absorption.
Hydration also plays a significant role in supporting food absorption. It is not uncommon that the prevalence of gut issues increases in races with high temperatures and high levels of humidity. This is due to dehydration's impact on the gut’s ability to absorb food.
Gut adaptation needs to occur during the training stage. To be successful, you will need to practice your nutrition using the type, quantity and frequency you intend to do on race day.
The final remarks
An Ironman is a big commitment. Therefore, working on your nutrition alongside your training preparation and planning a strategy well ahead of the event is indispensable to achieving a successful race.
“Eat like an athlete” is often confused with a diet with an abundance of fruits and vegetables and minimally processed food. However, after close to 10 years of working with athletes of all levels, I can tell you that “eating like an athlete” is nowhere near that.
Since most of the athletes I deal with are endurance athletes, their energy requirements are often high. Meeting these energy needs relying primarily on fruits and vegetables is nearly impossible. Those who dare to try it are likely to spend most of their day visiting the toilet… yikes!
Due to their convenience and energy density, energy gels, sports drinks and bars (aka processed foods) are also part of an athlete's regular diet.
However, due to this belief attached to what “eating like an athlete” should look like, many endurance athletes find themselves not fuelling correctly in their attempt to eat as clean as possible.
Even recently, in an interview for 220 Triathlon, professional triathlete Lucy Charles-Barclay shared her experience dealing with her nutrition. She mentioned how her need to be as professional as possible in every aspect of her life forced her to restrict her diet and not fuel properly. Lucy shared that she now understands the role nutrition plays and that energy restriction will keep her from becoming the world's best Ironman triathlete.
In contrast, Michael Phelps’ diet became very popular a few years ago. He regularly ate hamburgers and fried food to meet his 10,000 kcal needs and keep up with his daily 6 hours of training.
So, what does eating like an athlete actually look like? There is no particular food list you need to follow to ensure you are eating like an athlete. What you need is that your food choices help you achieve the following:
- Include sufficient energy to meet your caloric needs for optimal health and performance.
- Add enough protein to spread out your protein intake throughout the day.
- Include enough variety to assist with essential nutrient intake.
- Prioritise key fuelling times to support training adaptations.
- Be easy to absorb and digest when consumed close to training.
There is no single food that ticks off each of the points above, and that is not the intention. For example, a high in fibre food won’t be as easy to absorb and digest as a refined grain or sugar.
An example of a day of an athlete’s diet meeting these requirements is outlined below.
- 4:50 am - Pre-training meal: Toast with jam and fruit
- 5:30 am - Swim session
- 7:30 am - Post-training meal: Eggs on toast with spinach and a fruit smoothie
- 10:00 am - Morning snack: Fruit, greek yogurt and granola bowl.
- 1:00 pm - Lunch: Mixed greens, pasta and chicken breast with a glass of lemonade
- 3:30 pm - Afternoon snack: Fruit and nuts
- 5:30 pm - Pre-training snack: Muesli bar and fruit
- 6:00 pm - Run session
- 7:30 pm - Dinner: Salmon fillet, a bowl of rice and roasted veggies followed by sweets: ice-cream scoop
- 9:00 pm - Bedtime
As you can tell, the majority of the foods are those included in a regular “healthy/balanced diet”, but there is room for energy-dense foods. The meal frequency spreads energy intake throughout the day while including energy at key times near the training sessions.
Eating like an athlete does not mean restriction. Before you go on cutting things from your diet, have a look at what could possibly be missing. Focusing on what you need to add rather than remove will bring you far better results.
Racing weight is a term a lot of endurance athletes are familiar with. It is based on the premise that racing at a lower body weight will improve sports performance and achieve faster times.
Because of this principle, many endurance athletes frequently find themselves restricting their food intake in the hopes of getting leaner to achieve peak performance.
Thankfully, current sports nutrition evidence demonstrates that food’s true benefit lies in what we need to add and not so much in what needs to be subtracted.
These are the main reasons why achieving a racing weight shouldn’t be your top priority:
1. There is no evidence of a real benefit
This one shocked me. For years we’ve been told that leaner and lighter athletes achieve better results than their heavier counterparts. However, no data demonstrate that getting an athlete to drop weight and fat ahead of the competition is beneficial. In other words, Joe at 60kg may perform better than Peter at 65 kilograms, but nothing is demonstrating that asking Peter to aim for a racing weight 5kg lighter will improve his sports performance.
There is, however, plenty of evidence demonstrating the harmful impact energy restriction has on performance and health.
2. Losing weight requires a caloric deficit
This is achieved by either reducing energy intake, increasing energy expenditure or both. However, restricting energy intake can put the athlete at risk of developing energy deficiency, ultimately significantly compromising their performance.
3. Underminishes other nutrition benefits
Someone concerned with looking after their weight is less likely to do carb-loading, include nutrition during long training sessions and prioritise recovery after training. As a consequence, they are missing meaningful opportunities for supporting training adaptations and getting the most out of training.
4. Leads to frustration
Often, racing weight goals don't consider the athlete’s body composition, body weight fluctuations, and overall individual circumstances, making these goals very unrealistic.
Additionally, restricting calories does not always translate into weight loss. Your body’s priority is survival. When energy is missing, it conducts adaptations to preserve energy. Therefore, you are constantly tired and cranky, craving high-calorie foods and struggling to perform at the expected level.
5. Poses a health risk
Relative energy deficiency in sport (RED-S) is a severe problem. Consequences include impairments of metabolic rate, menstrual function, bone health, immunity, protein synthesis and cardiovascular health. In addition, weight-loss attempts and the desire to be leaner are risk factors for RED-S.
Health (left) and performance (right) consequences of Relative Energy Deficiency in Sport (RED-S) Source: IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update
What can you do instead?
I’m not saying that weight loss can’t happen. What I’m saying is that it needs to stop being your focus. Fuelling your body right, getting quality training sessions and prioritising your body’s overall recovery and ability to support the training adaptations will bring you better results than keeping a close eye on the scale.
I love the way Jesse Thomas talks about this after overcoming an eating disorder that put his career and life at risk. “Don’t aim for a number on the scale. Aim for consistently healthy habits (...) If you eat consistently healthy, sleep well, and get your workouts in, your body will adjust to the appropriate weight, and that is your ideal race weight.”
Mountjoy, M., Sundgot-Borgen, J., Burke, L., Ackerman, K. E., Blauwet, C., Constantini, N., ... & Budgett, R. (2018). International Olympic Committee (IOC) consensus statement on relative energy deficiency in sport (RED-S): 2018 update. International journal of sport nutrition and exercise metabolism, 28(4), 316-331.
Tomiyama, A. J., Ahlstrom, B., & Mann, T. (2013). Long‐term effects of dieting: Is weight loss related to health?. Social and Personality Psychology Compass, 7(12), 861-877.
Hicks, L. (2020, July 29). For young female athletes, losing weight may not improve performance. Retrieved from https://www.science.org/content/article/young-female-athletes-losing-weight-may-not-improve-performance
Tornberg, Å. B., Melin, A., Koivula, F. M., Johansson, A., Skouby, S., Faber, J., & Sjödin, A. (2017). Reduced neuromuscular performance in amenorrheic elite endurance athletes. Med Sci Sports Exerc, 49(12), 2478-2485.
The Ironman 70.3 is an endurance event with an approximate duration of 4 to 7 hours. Your body undergoes a constant effort, so physical and mental preparation are vital to achieving a successful result. In addition to proper training, nutrition plays a fundamental role in this physical preparation. Whether this is the first time you will compete at this distance or already have accumulated experience, mastering your nutrition strategy for an Ironman 70.3 will help you achieve the best outcome.
Days before the race… Let the feast begin!
Properly executed carbohydrate loading is essential, and its positive impact on performance during long-distance events such as an Ironman 70.3 is well-proven. However, there are particular guidelines you need to follow to ensure you maximise your fuel stores without compromising your gut comfort.
For an event such as the half ironman, the carb-loading needs to start 36 to 48 hours before the competition. This means that if your race is on Sunday, your carb-loading should start Friday and continue through Saturday.
Carbohydrates should be the priority for your meals. The trick is increasing carbohydrates without significantly increasing fat or fibre since this can cause stomach upset.
An intake of 7 to 10 g of carbohydrate/kg of body weight is recommended. This means that if you’re a 70 kg athlete, you should be having 490-700 g of carbohydrate per day.
Protein and fat intake should remain the same and, if possible, decrease a little bit.
“Thanks for the numbers, Gaby, but I don’t want to count grams for everything I eat”… alright, alright… here are some practical tips:
Split your meals into three main meals and three snacks. In each of these, make sure you’re having high carbohydrate foods (fruits, rice, pasta, bread, wraps, oats, etc.).
Adding energy-dense options such as sugar, jam, or honey to your meals helps increase your carb intake.
Drinks are pretty helpful as well. During these days, you can have a glass of juice or sugar-sweetened tea and have some Gatorade/Powerade throughout the day.
Try having 1 to 2 extra serves of carbohydrates per meal (i.e. if you usually eat half a cup of rice, try having a full cup).
This is an example of what your day would look like
Example of a day of carbohydrate loading for an Ironman 70.3
Well done! You completed your carb-load with success, but this is just the beginning… Today is the day! Breakfast is vital for your nutrition to ensure you start your Ironman 70.3 with your fuel tank full (you’ll need it, trust me).
Eat your breakfast 2 to 4 hours before the race. The advantage of triathlons (I see it as an advantage) is that usually 2 hours before the race starts, you need to be in transition getting all your gear ready, so the chances of being awake 3 hours before your start are relatively high… take advantage of it! I usually suggest that my clients have breakfast as soon as they wake up; that way, you have enough time for processing your breakfast.
Don’t, I repeat, DON’T eat something you’re not used to. Make sure you try your breakfast before with training.
The guidelines suggest having 1 to 4 grams of carbohydrate per kilo of body weight. So if you’re 70 kg, you’ll be having 70-280g 2 to 4 hours before the event.
Avoid fat intake as much as possible and keep your fibre intake low.
During the event… Avoid hitting the wall!
Have you heard this expression before? In Mexico, we sometimes say “se me acabó el Gansito” which translates to something like “I ran out of Twinkies”! And yes, it precisely means that you run out of fuel. You have your fat stores, but the body can’t burn these stores as quickly as it burns carbs, so performance starts decreasing significantly. To avoid this, it is necessary to include carbohydrate consumption during the race, and the recommendation is to have 30-90 g of carbohydrate per hour.
There is an excellent range of products you can have, such as gels, jelly beans, and high carbohydrate bars. If you have the talent and inclination, you can also make your snacks with bread, honey, jam or dried fruit. I usually recommend getting pre-packaged products as I find them easier to carry, but that’s your own choice. As long as you get your carbs in, there’s no big deal. Sports drinks are also beneficial since they help you stay hydrated and carb-ed at the same time.
Here’s a table with high-carbohydrate foods that can help you plan your nutrition for your Ironman 70.3:
||Grams of carb
|Honey stinger waffle
After the event… you crossed the finish line, but this is not over yet.
Congratulations! You crossed that finish line. What a tremendous accomplishment after all those hours of effort, not only during the race but during training as well… Well done! But guess what? Your race is not over yet, at least not nutritionally speaking. Recovery is essential! (No, I don’t mean beer.) Even though you executed your carb load, you had a great breakfast, and you topped up your carbs during the race, your body is running on empty, and you must recover those nutrients ASAP.
After such a considerable effort, you often don’t feel that hungry, but this doesn’t mean you shouldn’t eat – it’s the opposite! This is when your body is ready to get those nutrients and send them straight to your muscles so they can recover properly. So take advantage of what is offered to you at the recovery zone, eat that fruit, drink the choc-milk and gobble down a sandwich or an energy bar.
Just as you need the right nutrition for an Ironman 70.3, hydration is critical. Losing as little as 2% of your body weight in water can significantly negatively impact your performance, so make sure you drink water before, during, and after your race.
Other general tips for long-distance triathlons
Caffeine intake has been shown to impact athletes’ performances positively. Therefore, having your breakfast with a strong cup of coffee with sugar/honey (carbs!) could be beneficial. Of course, this is without even mentioning the other great benefit of having coffee in the morning.
Don’t try anything new during the race. This is very important. Make sure you try all that I’ve mentioned before during training to know how your body reacts to it.
More is not always better. Yes, 60 grams of carbohydrate can help you perform better, but this doesn’t mean that 120 grams will give you superpowers… don’t do it! Your gut has an absorption tolerance of ~60 grams of glucose per hour, so having more than this increases your chances of having gastrointestinal discomfort.
Do you have any questions? Would you like to share your experience with me? I would love to hear it! firstname.lastname@example.org
Good luck at your race!
Cermak, Naomi M., and Luc JC van Loon. “The use of carbohydrates during exercise as an ergogenic aid.” Sports Medicine 43.11 (2013): 1139-1155.
Higgins, Simon, Chad R. Straight, and Richard D. Lewis. “The Effects of Pre exercise Caffeinated Coffee Ingestion on Endurance Performance: An Evidence-Based Review.” International journal of sport nutrition and exercise metabolism 26.3 (2016): 221-239.
Jeukendrup, Asker E. “Nutrition for endurance sports: marathon, triathlon, and road cycling.” Journal of sports sciences 29.sup1 (2011): S91-S99.
Rankin, Janet Walberg. “Dietary Carbohydrate as an Ergogenic Aid for Prolonged and Brief Competitions in Sport.” IJSNEM 5 (1995).
The essential ingredients in fuelling your personal best
I’ve been a dietitian for more than nine years. During this time, I’ve been a strong advocate for nutrition and how this can make a significant positive impact on endurance athletes’ sports performance and health. In addition, being a triathlete has helped me understand the main struggles endurance athletes face when it comes to improving their nutrition.
Information overload. Everybody seems to have an opinion on the best diet to follow, the new magical supplement and the #1 food you should avoid.
Constant body battle. Your body refuses to change despite how much you train or look after what you eat.
You are going nowhere. It feels like you are barely improving. You are often cranky, lacking energy and unable to bring out your best self.
Understanding how to use nutrition to your advantage is fundamental to unlocking your true potential. The following are key principles I have identified as paramount to maximise your performance and move your results from average to outstanding.
#1 - Fuel your core
Fad diets are not sports nutrition
A common mistake I see is thinking that nutrition is a quick fix. Unfortunately, I know many people wasting time and energy finding that ‘magical supplement’ or following a trendy diet hoping it will be the solution to all their problems.
As much as we all would love a quick fix, unfortunately, that is not the case. Fuelling your core is all about getting your foundations right. Ensuring your diet has all essential nutrients that you are consistently fuelling throughout the day and paying attention to hunger and fullness cues.
Your nutrition needs to include all essential nutrients in your diet, so your body has the vital tools it needs to work as efficiently as possible and put up with the endurance demands. Carbohydrates, proteins, fats, fibre, vitamins and minerals are essential nutrients your body needs daily. When one of these nutrients lacks, the body needs to make adjustments that can ultimately create imbalances.
Diets advising against consuming any of these nutrients are likely to be unsustainable and to put both your health and performance at risk.
#2 – Fuel your endurance
Burning calories is part of the activity, not the purpose
The ultimate purpose of your training sessions is to provoke a physiological adaptation that eventually will lead to improved performance. This is because your systems receive different stimuli depending on the type of training, and your body adapts in different ways. Ultimately, the idea is that you can perform the same effort faster, better or easier next time.
It turns out that nutrients and energy are critical for each step along the path. Your body needs the energy to complete that training session, but it also needs nutrients for those adaptations to occur.
Fuelling your endurance means ensuring that you can commence your training sessions feeling energised, maintain your energy levels throughout the session and optimise your recovery and performance adaptations afterwards.
A frequent error I see athletes making is underestimating their training sessions. They often think the session won’t be as hard or long, so eating before or during is unnecessary. However, even if you can complete your sessions in a fasted state, many athletes would likely benefit from consuming energy beforehand.
Another essential thing to keep in mind is the importance of prioritising post-workout recovery. Right after your training session, your body becomes very efficient at absorbing essential nutrients that will replenish your fuel stores and repair your muscles. So in the first hour after your training session, remember the following: Refuel, repair and rehydrate.
- Refuel – Add carbohydrates to your meal
- Repair – Add protein and essential amino acids to support your muscles
- Rehydrate – Add fluids
#3 – Fuel your performance
A successful race tomorrow starts with what's on your plate today
“Do not try anything new on race day” is a saying known by most athletes. As important as I think this is, I believe most people do not adequately implement this phrase. Just because you ate an energy gel while running and nothing happened, it doesn’t mean that having five while running a marathon will go as smoothly. Therefore, it is important to try things the way you intend to do them during the event.
Doing this will help you decide if what you are planning is truly going to work or if some adjustments need to get made BEFORE completely ruining a race and months of preparation for it.
Fuelling your performance is all about feeling confident at the start line, knowing you have a successful plan to ensure you will feel energised during the event. As a result, the likelihood of gut issues is low and you will be crossing that finish line feeling strong.
#4 – Fuel your soul
Food is fuel and much more
This principle took me the longest to understand, mainly because they don’t teach this at uni. Nutrition and sports units teach you about nutrients, pathways and systems for endurance athletes but rarely about the influence food has on mood and its cultural and social implications. All this seems secondary and irrelevant.
I thought that what was pulling me towards eating certain foods was weakness and lack of willpower. I used to think that maybe I didn’t want it bad enough. Today I understand that food is more than energy and fuel; food is connection, family, joy. Having a truly healthy and balanced diet also means embracing and accepting these other components of food.
I learned that I needed to nourish my body but also to nourish my soul and the best part is that they complement each other. This realisation is what helped me to truly connect with food and improve my relationship with it. Today I see food as an ally. It brings energy, health and joy to my life, and I’m sure it can to yours too.