Most Triathletes Get Carb Loading Wrong — Here’s How to Do It Properly

Carb loading is one of the simplest and most effective ways to boost your performance on race day — yet it’s also one of the most misunderstood. For triathletes, proper carb loading can mean the difference between feeling strong through the final miles or hitting the wall halfway through the run.

The goal isn’t to eat one big pasta dinner the night before. It’s about strategically increasing your carbohydrate intake in the days leading up to your triathlon so your muscles are fully stocked with glycogen — your body’s most efficient fuel for endurance racing.

Here’s how to carb load properly, how much to eat, what to avoid, and how to tailor your plan for sprint, Olympic, 70.3, or Ironman distance events.

What Is Carb Loading?

Carb loading is the process of increasing your carbohydrate intake before an endurance event to maximise your glycogen stores. Glycogen is essentially your body’s “premium fuel”. It’s the energy you burn during higher-intensity efforts like racing, climbing hills on the bike, or pushing through the back half of a run.

The more glycogen you have in the tank at the start line, the better your body can maintain pace, delay fatigue, and avoid hitting the wall.

For triathletes, this matters even more because you’re combining three sports back-to-back. You’re using a lot of glycogen across a long period of time — especially if you’re racing long-course.

Do Triathletes Really Need to Carb Load?

While you hear a lot about carb loading for marathons, you don’t usually hear as much talk about carb loading for triathlons. So, do triathletes actually need to carb load? The short answer is: it depends on the race distance.

Sprint Distance:
Carb loading isn’t usually necessary for efforts under 90 minutes. Your body won’t fully deplete glycogen during a sprint, especially if you’ve eaten well in the days leading up to the race.

Olympic Distance:
Helpful, but not essential. A light carb load the day before can top up your stores and help you maintain strong energy through the run.

70.3 (Half Ironman):
Recommended. You’ll be out there for several hours, and glycogen stores matter here. Proper carb loading can help you feel stronger later in the race — especially on the run.

Full Distance (Ironman):
Essential. You’re racing long enough that starting with fully topped-up glycogen stores makes a major difference. A solid carb load can significantly improve how you feel in the second half of the bike and throughout the marathon.

When Should You Start Carb Loading?

The ideal timing depends on your race distance. For an Olympic or 70.3 race, 24 to 48 hours of increased carbohydrate intake is usually enough. For a full-distance Ironman, you should aim for at least 2–3 days of higher carb intake to fully maximise your glycogen stores.

Many athletes make the mistake of starting too late — assuming a single pasta dinner will do the job. But that’s nowhere near enough to top up your stores before a long race.

Spacing your carbs out over 48–72 hours allows you to fuel properly without feeling overly full, bloated, or uncomfortable. It also gives your body time to store glycogen efficiently and helps avoid the heavy, sluggish feeling that can come from trying to cram everything in at once.

How Much Should You Eat? (Carb Targets)

Carb loading is more strategic than simply eating more food. For each day of carb loading, most sports nutrition guidelines recommend the following carbohydrate ranges:

• 5–7 g/kg of body weight for Olympic distance
• 7–10 g/kg for 70.3 and Ironman races
• Up to 12 g/kg for athletes with very high energy needs

To put this into perspective:

• A 60 kg athlete might aim for 420–600 g of carbs per day before a 70.3 or Ironman
• A 65 kg athlete might aim for 455–650 g
• A 70 kg athlete might aim for 490–700 g

It looks like a lot — because it is. But when you spread it across the entire day, it becomes manageable (even if you might not want to look at another carb by the end of it!). And more importantly, it genuinely makes a difference in how you feel on race day.

It’s also worth noting that while the recommended ranges (g/kg) are the same for men and women, male athletes often end up with slightly higher total carb targets because they typically have more lean muscle mass and therefore larger glycogen stores.

My experience: Having completed races with and without proper carb loading, I’ve noticed a big difference in how I feel on race day. For long endurance events like Ironman, my strategy now is to gradually increase my carb intake over three days. I’ll usually aim for around 400 g on day one, 500 g on day two, and 600 g on day three — a manageable amount for me and one that helps me start the race feeling properly fuelled.

What to Eat While Carb Loading

The goal is to eat more carbohydrates — not just more food in general. To reach your carb targets, you’ll naturally end up eating more calories than you’re used to, and while the idea of endless bread, pasta, and sweets might sound fun at first, the novelty fades quickly. After a day or two, it can actually become quite unpleasant if you’re relying only on heavy, dense foods.

The easiest way to make carb loading tolerable is to focus on simple, easily digestible carbs that won’t upset your stomach. Liquid carbs are especially helpful (like juice or sports drinks) because they boost your intake without making you feel overly full.

Good choices include:

• Rice, potatoes, sweet potatoes, and pasta
• Bagels, bread, and tortillas
• Bananas
• Pancakes and waffles
• Cereal and oatmeal (avoid high-fibre varieties)
• Fruit juice, soft drinks, and sports drinks
• Rice cakes, pretzels, and crackers
• Sweet snacks like candy, muesli bars, and Rice Krispie treats

It’s also smart to keep fats and fibre lower than usual during this period. Both can slow digestion, leave you feeling overly full, and increase the risk of GI issues on race day — something no triathlete wants to deal with.

One more important note: carb loading only works if you’re well hydrated. Stored glycogen holds onto water, so if you’re dehydrated, the carb-loading process is far less effective. Adequate hydration (plus some sodium) also helps reduce the risk of GI issues on race day. Make sure you’re drinking enough water and including electrolytes along the way, especially if you’re racing in hot conditions.

What Not to Eat While Carb Loading

While you’ll naturally end up eating more than usual during a carb load, it’s not an excuse to eat giant, heavy meals. Overdoing it can leave you feeling bloated, sluggish, heavy, and uncomfortably full — and worst of all, it can set you up for GI issues during the race.

To avoid that, try to minimise:

• High-fibre foods (beans, lentils, fruit, raw vegetables, large salads, etc.)
• Very fatty foods (such as fried foods, creamy sauces, and greasy meat)
• Excessive protein
• Any new or unfamiliar foods
• Large portions late at night

And most importantly, avoid having a massive dinner the night before the race. Big, heavy meals late in the evening can disrupt your sleep and leave you waking up feeling slow and weighed down — which is the last thing you want heading into the swim. Instead, aim to eat your larger meals earlier in the day and keep the evening lighter and easier to digest.

Signs You’re Carb Loading Correctly

If you’re carb loading properly, you’ll likely notice a few clear signs:

• A small amount of weight gain (1–2 kg is normal — it’s water, not fat)
• Muscles that feel full or “topped up,” without feeling overly bloated
• Higher energy levels
• Reduced hunger as your carb intake increases
• Stable digestion — you’re not running to the bathroom

It’s also a good idea to track your food intake while carb loading, either manually or with a nutrition app. Personally, I like using MyFitnessPal because it’s free and easy to use. Although I’ve also had success with the Fuelin App recently, which provides personalized nutrition recommendations using AI. Fuelin is especially helpful if you’re unsure how much to eat, new to carb loading, or want guidance on your overall fuelling strategy.

Final Thoughts

Carb loading is simple — but doing it well requires a bit of planning. For triathlon, especially long-course, increasing your carbohydrate intake in the days before your race can significantly improve your energy, endurance, and overall performance.

Track your carbs, choose easy-to-digest foods, spread your intake evenly across the day, and avoid the temptation to overdo it. And like any race-day strategy, it’s worth practising your carb-loading plan ahead of time during a key training weekend, so you know exactly what works best for you.

With a well-executed carb load, you’ll arrive on the start line fuelled, confident, and ready to race.