How to carb load for your long distance triathlon - Ironman or 70.3

If you’re racing an Ironman or 70.3, carb loading can make a massive difference in how strong you feel late in the day. Done properly, it helps top up your glycogen stores so you have more available energy to work with when the race starts getting real.

And no, this does not just mean smashing a giant pasta dinner the night before.

Here’s what carb loading actually is, why it matters, and how to approach it properly in the final week before your race.

What carb loading is actually doing

Your body stores carbohydrate in the form of glycogen, mainly in your muscles and liver. Glycogen is one of your most important fuel sources during endurance exercise, especially when you’re working at moderate to high intensities for long periods.

In an event as long as an Ironman, glycogen availability matters a lot. Even if you’re fueling well during the race, starting with fuller glycogen stores gives you a much better chance of maintaining energy, pace, and decision-making deep into the event.

By increasing carbohydrate intake while your training load comes down during taper week, your body can store more glycogen than usual. This can help delay fatigue and reduce the chances of completely falling apart later in the race.

Why carb loading matters for Ironman athletes

Ironman is not a normal endurance event. You’re asking your body to perform for the better part of a full day. That means your energy demands are huge, and if you start under-fueled, you’re already behind before the gun even goes off.

A lot of athletes underdo this.

They train hard for months, taper well, get to race week, and then either eat too “clean,” don’t increase carbs enough, or leave it all until the final meal the night before.

That’s not the play.

Good carb loading is a process. It happens across several days, not one dinner. The goal is to gradually raise carbohydrate intake as training volume drops, while also making smart food choices that your gut can handle.

A simple Ironman carb loading plan

Here’s a practical way to think about the final week.

3-7 days out: start the taper

At this stage, your training volume is beginning to come down, but you do not need to force-feed carbs yet.

A good target here is around 4 to 5 grams of carbohydrate per kilogram of body weight per day.

Keep meals balanced and normal. Think moderate carbs, solid protein, and foods you digest well.

Examples:

• oatmeal with berries and honey

• rice or quinoa bowls

• potatoes, fruit, grains, and lean protein

The goal is just to begin the shift while keeping things controlled.

2 days out: ramp it up

Now you’re getting into the real loading phase.

Carbohydrate intake can move toward 7 to 8 grams per kilogram per day.

This is also where it often makes sense to start reducing fat and fibre a little, especially if you’re someone with a sensitive stomach. You want to make it easier to get the carbs in without feeling overly full or bloated.

This is a good time for foods like:

• bagels

• rice bowls

• pasta

• lower-fibre cereals

• juice

• toast with jam or honey

You’re trying to make carbs easy to eat and easy to absorb.

1 day out: make digestion a priority

At this point, the goal is high carbohydrate intake without creating stomach issues.

A good target is around 8 to 10 grams per kilogram.

Now is the time to lean more heavily on lower-fibre, easier-to-digest carbs. This is not the time to load up on giant salads, tons of veggies, or random “healthy” foods that sit heavy in your stomach.

Hydration: make sure to sip on water all day WITH electyrolytes in it, if you just do pure water you'll flush your system of all the good electrolytes you'll need for race day

Simple options work well:

• white toast with jam

• white rice

• pancakes

• applesauce

• bananas

• sports drink

• pretzels

Do not suddenly eat foods you never normally eat.

The goal is to arrive at race morning feeling fueled, not stuffed.

Race morning

On race morning, you still want to top things up.

Aim for a carbohydrate-rich breakfast about 3 to 4 hours before the start, and keep it light, familiar, and easy to digest.

A simple example could be:

• a bagel with honey or oats with maple syrup

• a banana

• sports drink

Nothing fancy. Nothing high fibre. Nothing new or risky.