How To Carb Load For An Ironman Triathlon
When I speak to triathletes about carb loading, they usually tell me, “Yeah, I do it.”
And it normally means eating a big pasta meal or pizza before the race.
But it is so much more than that, and this is one of the carb loading mistakes most triathletes make, which could cost them hours off their finish time.
In this article, we're going to go through everything that you need to know to carb load properly before an Ironman triathlon.
Carb loading has the potential to significantly improve your performance across all three disciplines, especially during those crucial final hours on the run course.
It's definitely worth doing properly, but if done incorrectly, it can cause unpleasant gastrointestinal symptoms like bloating, diarrhoea, or abdominal cramps.
We'll cover what to eat and what not to eat, how long before your race you should carb load, and many other helpful tips to ensure you complete your best Ironman possible!
Carbohydrate loading is a favorite topic of mine because it's such a powerful tool, but it's not as straightforward as a lot of people think, and that's a good place to start.
What proper carb loading ISN'T
Let's talk about what proper carb loading isn't:
It isn't just eating a big pasta meal the night before
Nor is it just eating a bit more carbs the day before your race
It isn't going low-carb first to then be able to carb load properly (which is only in part because that's no fun)
Instead, it's eating a large and specific amount of carbohydrates in the right timeframe before your race, while avoiding or reducing certain food groups.
That sounds pretty complicated, right?
Don't worry, it's not that bad, and I'll walk you through everything.
I've also created a carb loading plan which you can download for free to help you out.
Why carb load for an Ironman?
This all comes down to energy reserves and what you need to fuel you through a 140.6-mile race that might take 9-17 hours to complete.
Your body has two main sources of energy: fats and carbohydrates.
Fats are essentially unlimited when it comes to energy because the average person has over 50,000 calories worth of energy stored in fat.
But carbohydrates are limited, and the average person only has about 2,500 calories worth of carbs stored in the body as glycogen.
When you do an Ironman, even though it’s lower intensity in relative terms, a significant proportion of energy will come from carbohydrates, particularly during higher intensity efforts on the bike and run. Since carbs can run out, they must be a big focus before and during your race.
By carbohydrate loading, you maximise or even exceed the usual storage amount of glycogen, which is extremely helpful because it reduces the chances of you bonking, or hitting the wall.
That's the term for reaching a critically low level of glycogen in your muscles, which means you have to reduce your pace and probably feel dreadful.
This typically happens during the marathon portion of an Ironman, when many triathletes start to struggle.
Carb loading has been shown to improve endurance performance by about 2-3%. That might not sound like much, but over the course of a long Ironman day, this can make a dramatic difference:
16 hours —> 15 hours 30 mins
14 hours —> 13 hours 35 mins
12 hours —> 12 hours 38 mins
10 hours —> 9 hours 42 mins
How much to eat
When carb loading, the guidance is to eat about 10 grams of carbs per kg of bodyweight per day, which is actually quite a lot.
Let's say you're 70 kilos, that's 700 grams of carbohydrates.
To give you some perspective, this is the carbohydrate content of some different food which people might eating during a carb loading period.
A cup of cooked pasta has about 45g of carbs
A medium banana has about 27g of carbs
A slice of white bread has about 20g of carbs
A cup of cooked white rice has about 45g of carbs
A 500ml bottle of sports drink has about 30-60g of carbs
If you only include the amount of carbs here, that's 2,800 calories (700 grams × 4), and then you've still got to include protein and fat too.
This is why having a plan in place is so useful.
If most people simply just up their carb intake a bit compared to normal, eat a bit more pasta or rice, they won't get anywhere near this 10 grams per kilo mark.
What carbs to eat
What sort of carbs you eat can have a significant impact on how well the carb loading goes and whether you get any sort of gastrointestinal upset during your Ironman.
For everyday, healthy nutrition, I would normally suggest you eat wholegrain carbohydrate varieties in most instances because the nutrient profile is healthier overall, and it's better for you.
But when it comes to carb loading, this isn't the case.
With carb loading, generally, the simpler the carb, the better.
So this is one of those times when you absolutely should go for white bread over wholemeal bread and white rice over brown rice, and you should make sure you include some sweets and sugary drinks in your carb load.
The wholegrain varieties contain more fiber, more protein, and more fat, and you don't want those things in any large amount when you're carb loading.
Your focus is carbs, and those other nutrients are just going to make you feel more full and bloated.
They are also more likely to remain around your gastro tract on race day, meaning they could contribute to an upset tummy during your swim, bike, or run.
Sweets and carbohydrate-based drinks are easy ways to consume simple carbohydrates with minimal protein, fat, or fibre, so they work perfectly as part of a carb load.
So stock up on your favorites and get them down you!
How long should you carb load for?
Next up on your list of things to tackle is how long to carb load for and whether you should do a low carb period first.
The current evidence suggests that even 24 hours of proper carb loading is probably sufficient to maximize glycogen stores before something like an Ironman.
A study compared muscle glycogen stores after 24 and 72 hours of carb loading and found no significant difference in the measurements.
Now, my personal opinion is that for an Ironman, it's worth starting around 36-48 hours out and transitioning to lower-fibre foods 72 hours before your race.
If you have a busy life or job or are doing a little shake-out session, it ensures you'll be as well topped up as possible.
You also don't need to go on a low carb diet before you start carb loading.
In terms of glycogen storage, we know you can get the same results from a standard diet and going straight into a carb-loading diet.
If you do try a low-carb approach first, you'll probably end up feeling miserable and rubbish, which isn't what you want in the days before a big race. So don't do that.
Hydration
When you're carb loading, you need to keep an eye on your hydration too.
From my own personal experience and from working with triathletes, it's really common to feel more thirsty than usual when you are carb loading.
So be conscious of your fluid intake and plan to drink a little more than usual. I usually add electrolyte tablets or just a bit of normal table salt to my drinks over the days when I'm carb loading.
Unless you have a specific medical condition and have been advised not to do this, this shouldn't be an issue, especially over the short term, because any excess salt should be eliminated through urine.
The reason behind this thirst is that carbohydrates are stored as glycogen, and for every 1 gram of glycogen you store, you store 3 grams of water. Because you’re consuming a much higher amount of carbohydrates than usual, your body is going to have to use water from your blood plasma as storage, and hence, you become dehydrated and feel thirsty relatively quickly if you haven’t proportionately increased your fluid intake.
Bottom line, keep up with your fluids while you carb load.
This whole pre-hydration strategy is actually something I go into much more detail in my triathlon nutrition course, the TriFuel Academy, which is included in a membership to The Hub.
This is my nutrition membership designed specifically for triathletes, to help them train, race and recover to the best of their ability.
Is it unhealthy?
Now you may have been reading all of this and thinking this is a heck of a lot of carbs, and you're saying to eat less protein, fat, fibre, and wholemeal carbs... Is this really healthy?
Well, there's not really anything unhealthy about it as such.
We're talking about a short, max 2-3 day period of higher than usual carb intake. Your body should be able to handle this without any problem unless you already have a diagnosis like diabetes.
And because it is so short, we're not worried about vitamin or mineral deficiencies either.
Plus, if you've been training for an Ironman, then you've likely done a fair amount of exercise, and we know exercise in its various forms improves the body's ability to handle carbohydrates.
So really, there shouldn't be any issue here.
Extra tips
So now let's go over some extra tips for carb loading which I think make a world of difference for triathletes:
1. Taper Your Daily Intake
Eat more in the morning and afternoon so that you can eat relatively less in the evening.
If you've ever eaten a load of food before bed, you'll know that uncomfortable sensation that can happen when you're just too full to sleep.
You lie there tossing and turning and may even get the sweats too — not great prep before your race.
2. Include Carb-Rich Drinks
Make sure you include carb-rich drinks in your plan.
If you consume carbs just as whole foods, they can feel like way too much, so liquids are an easy way to add carbs to your day.
Sports drinks are great for this purpose because they're usually full of simple sugars and a bit of sodium, which helps with hydration.
3. Practice in Advance
Don't just plan to do it for the first time a few days from your race and throw caution to the wind.
Practice once or twice at least 4-6 weeks out from your race, perhaps before a big training weekend.
Even if you just try it for 1 day, make sure you feel comfortable doing it and can tolerate all the foods you've picked.
If it doesn't work well, you've got time to change things and fine-tune it so that come race day, it's no stress.
4. Use a Carb Loading Plan
Because of pretty much everything I've mentioned in this article, having a plan is the best way to carb load properly.
I've created a carb loading plan for Ironman triathletes which you can download for free
I've used it before with success for many races, including several Ironman events, and it will help to give you an idea of what you might want to eat.
You can change food to suit your own preferences so that it's perfect for you.
Another aspect of Ironman racing is whether to use caffeine in long distance triathlon, and I’ve created an article on caffeine use in Ironman triathlon to dive into this for you.
