The Best Triathlon Diet For Racing
So your triathlon is coming up and you’re wondering what the optimal triathlon diet looks like. You’ve come to the right place!
Welcome to my complete triathlon nutrition plan that will lead you from the days before your race, right through to post-race nutrition.
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The science behind a triathlon diet
First, let's do a quick dive into the science behind triathlon nutrition, as this will help to contextualise the rest of the article.
Your body has two major sources of fuel for energy, fats and carbohydrates, and you use a combination of the two over the course of your triathlon.
Most people have about 2,500 calories of energy stored as carbs (in the form of glycogen) and around 50,000 calories of energy stored as fat.
So that’s a pretty much unlimited supply of fat and a fairly limited store of carbs.
Carbs are what provide your short term energy and also significantly contribute to moderate-high intensity exercise. 2500 calories of carbs is only enough for about 90 minutes of hard, steady exercise.
Many triathlons are going to take more than 90 minutes to complete, so you will need to make sure your carb levels are as high as possible before the race, top them up during the race, and replenish afterwards.
If you run out of carbs, you will ‘bonk’ or ‘hit the wall’, which is the term used to describe getting to a critically low level of glycogen stores.
Your body notices this and starts to put on the brakes as a safety mechanism, meaning you’ll end up having to reduce your pace - and it will feel dreadful!
In addition to that, for the vast majority of triathletes carbs are the most important fuel source for optimal performance, and hence the focus during racing is on carbs.
Dietary protein and fat don't contribute meaningfully to short term energy and are also harder and slower to digest which is just going to increase the risk of gastrointestinal upset, so that's why we generally use sport specific, easily absorbable carbohydrates to fuel a triathlon.
The long and short of it being: you will be hearing a lot about carbs in this article!
Before the race: Carb loading period
Carb loading is one of my favorite topics because it is so frequently misunderstood! Lots of people like to insist that you don’t need to do it - which is true, it’s not absolutely necessary…but it is extremely beneficial!
The aim of carb loading is to maximise your body’s carbohydrates stores so that you have as much fuel in the tank as possible before you start the race.
In practical terms, this means eating more carbs than usual in the days before your race.
While a lot of triathletes think of carb loading as just eating a big pasta or rice dish the night before, there’s actually way more to it than that.
I have a whole article which provides an ultimate guide to carb loading, so I won’t repeat myself here, but I will outline some of the most important points to do with carb loading:
Start carb loading about 36-48 hours before your race.
Eat 8-10 grams of carbs per kg of bodyweight per day.
Aim for low fibre, low fat and low protein foods.
Eat more in the morning and less towards the evening.
Don’t do any super hard training during the carb load period.
The last key thing with carb loading is that it is so important to plan it out. That way you can be sure you are getting all the carbs you need.
You can make your own triathlon meal plan, or follow my carb loading meal plan. It’s free to download and shows you what sort of foods I’d recommend for carb loading.
A favourite carb loading snack of mine! White bagels with jam and banana
Triathlon Nutrition Race Day
Now you know what to eat the day before a triathlon, let’s look at what to eat on race day. I will cover breakfast, your pre-race snack and the importance of hydration at this stage.
What to eat for breakfast before a triathlon
I would always advise eating breakfast before a triathlon. A well planned breakfast can help top up your carb supplies and make you feel good before you get going.
You don’t want to eat too much or anything too heavy; you are going to be racing soon and you don’t want to still be digesting a big meal.
Stick to light, simple carbs and make sure you practice your meal in your training period to check it doesn’t cause any stomach issues.
Maybe you could try white bread and honey, or a simple cereal like cornflakes or rice krispies!
This picture highlights the guidance around how many grams of carbs to eat depending on how many hours before the race you are eating.
You don’t have to hit these numbers, and in reality most of you probably won’t. If you can get to at least 1g of carbs per kg of body weight for your pre-race breakfast then you’re putting yourself in a good position.
Pre-race snack
If you have had breakfast a couple of hours before the race, then it’s useful to have something else just before your race to help top your stores up again.
The easiest option is a gel about 15 minutes before you start the swim. Anywhere between 25-60 grams of carbs is perfect.
As ever, practice this in your training period to make sure your body can hold it!
Hydration
A quick word on hydration before your 70.3. I usually suggest having a 500ml of water with breakfast mixed with a sports electrolyte tablet containing at least 250 mg of sodium, preferably more like 500 mg of sodium.
This will maximise your hydration going into the race because it'll improve how much fluid you absorb.
What to eat during a triathlon
There are two principles to follow when thinking about triathlon foods during the race. The first is that the longer you are racing for, the more you need to consume.
The second is that the higher the intensity you are working at, the less your body is able to absorb nutrition.
What this means is that anything that makes intensity higher - be that fatigue, dehydration, heat stress, pushing harder than you planned - all that will affect how much nutrition you can absorb.
Bear this in mind as we start this next section of advice.
Bike nutrition
It’s not really possible to fuel during the swim section (for obvious reasons), so the bike section is where the magic starts.
I usually advise athletes to start taking some form of carbs from about 15 minutes into the cycle.
You want to start getting them into your system before you get tired, because they will take a while to be absorbed and then used by your body for energy.
During the bike section most long-distance triathletes can tolerate somewhere between 60-90 grams of carbs per hour.
Use a product that contains multiple carb sources, which would be glucose or maltodextrin and then fructose.
Products containing a combination of carb sources have been proven to maximise the amount of carbs you absorb and use for energy, which will ultimately help your performance.
Now there are plenty of different products out there that fit the bill and this is a highly personal area.
You’ve got to find a product you like the taste of, that you can use comfortably on the bike and use repeatedly, be that gels, drinks or bars.
As with everything to do with a triathlon diet: practice your bike nutrition beforehand! Practice race pace efforts and make sure that it all goes ok, including a run afterwards with your exact race nutrition set up.
You can either carry all your nutrition with you, or make use of the race aid stations. See what works best for you.
Bike Hydration
You should be consuming around 500ml of fluid per hour during a triathlon. This is enough to help mitigate the effects of dehydration but shouldn't be so much that you over hydrate or cause tummy issues.
Obviously, this can change from person to person but it’s a good baseline amount.
You should almost always make sure your bike fluid contains sodium (unless you’re using salt tablets, as discussed later), because you lose a lot of sodium through sweat, but you need it because it is vital for a load of bodily different functions.
If you drink plain water on its own and don't include sodium then you can end up with blood sodium levels lower than the normal range which in turn can lead to a condition called hyponatraemia.
The aim is for your fluid to contain at least 250mg of sodium per 500mls of fluid, or 500mg of sodium per litre.
Some people need more and some people need less, and that's quite individual and also depends on things like the climate, but those numbers are a pretty good starting point.
It should tell you on the packet of sports nutrition products how much salt or sodium it contains.
By the way salt is the generic term we use for sodium chloride. Sodium chloride is made up of 60% chloride and 40% sodium.
That means if your packet says 1g of salt there's 400mg of sodium so you can still work out how much sodium your product contains.
The last thing to add is that you could have water and then use salt tablets or sticks. This is a totally viable option and many triathletes will opt for this.
This allows you to separate out their carbs and hydration, allowing you to fine-tune your nutrition plan.
Run nutrition
You are more likely to experience GI distress during the running section of your triathlon than the cycling section.
The mechanical nature of running combined with the likely fatigue and dehydration which will have accumulated over the race increases the risk of GI upset and reduces how much nutrition you can absorb.
Therefore, while I usually recommend 60-90g carbs per hour, I don’t think this is realistic while running. Instead, aim for around 50g per hour, as a ballpark figure.
If you can tolerate more than that then that’s fantastic, but don’t be disappointed if you can’t.
As always, practice in training! Don’t try anything new on race day that you haven’t practiced exactly during training runs. You don’t want to risk it on the day, as there are many stomach issues you can get during exercise which can really mess up a race!
It’s up to you whether you decide to make use of the aid stations or carry your own supplies. That just comes down to personal preference.
Run hydration
As for run hydration, I suggest around 300-400mls of fluid per hour as a good starting point here.
That's about 2 cups worth at most aid stations. Although this does depend on your personal physiology and the conditions you’re racing in, if you hydrate properly before the race and during the bike leg, then you should be fine for sodium by this point and can focus on plain water.
You don't have to stop at every aid station; twice an hour with a cup at each should be enough. Though obviously if you feel thirsty, take more!
If it is particularly hot or humid or you're out there for 6 or more hours then sodium intake becomes more important again.
If that's the case, consider either taking a bottle with sodium in, using salt tablets or using the course hydration options, and follow the sodium guidance mentioned earlier.
Post-triathlon nutrition
The best way to approach post-triathlon nutrition is to think about the Four Rs: Refuel, Repair, Rehydrate and Rest.
Refuel
To refuel, you should try to get 1g carbs per kg body weight per hour, for a few hours after your race.
Carb-based drinks are great for this, though you might understandably be sick of those by now! Sweets, white bread and white pasta are great alternatives.
Repair
You need to eat protein after a race to help your damaged muscle tissue begin to repair itself. Aim for at least 20g protein, up to about 40g of protein. This could be from a protein powder, meat or fish, or protein found in milks like cow’s milk or soya milk
Rehydrate
It is important to drink plenty of fluid in the 4-6 hours after your race. 300-500 mls per hour is a good place to start, but it doesn’t have to be exact; just make sure you keep drinking consistently after you cross the finish line.
It is best to drink water + sodium to replenish your depleted electrolytes. Aim for at least 250mg of sodium per 500ml of water.
If you don’t have access to sodium, eating salty food will also do the trick - but keep drinking!
Rest
This one is a bit of a no-brainer ! Get plenty of sleep and don’t get back to training for a week or so after your triathlon. Celebrate your achievement - you deserve a break!
Triathlon Diet FAQs
What is the best triathlete diet?
The best triathlete diet balances protein, carbohydrates and fats. It’s important to consume sufficient carbs and protein to help you fuel your training and then recover properly.
In the days before a race, the focus should switch to simple carbs, so your carb stores are topped up for the big day.
How much should a triathlete eat?
A triathlete should eat enough to cover their normal daily needs and then replace the calories burnt through exercise (plus a bit extra to provide energy to adapt and improve!).
This will vary person to person depending on weight, age and metabolism.
How many calories do triathletes eat a day?
Depending on your weight, sex, age and fitness, the amount of calories a triathlete consumes in a day will vary.
You need to replace all the calories burnt during exercise, so you should be eating in excess of the average calorie requirements for men (2000 calories per day) and women (1500 calories per day).
What do triathletes eat during training?
During training many triathletes eat simple carbs to fuel their race. These could be in the form of gels, dried fruits, energy bars, sweets or carb-based drinks. Triathletes should be drinking lots of fluid, preferably with electrolytes, to replace sodium lost through sweat. The same applies for during the race.
And there you have it!
My triathlon/half ironman diet plan advice, collated from years of experience as a triathlon nutrition coach. I hope you have found it helpful and now feel like you are ready to execute the perfect triathlon diet!
