Triathlon Nutrition: Fueling For an Ironman 70.3 Race

An Ironman 70.3 race is not a small challenge. It consists of 1.2 miles of swimming, a 56 mile bike ride and 13.1 miles of running to finish the race. Training prepares your body to go the distance, but it’s your triathlon nutrition strategy that will determine how well you can put that training to use on race day. 

Fueling properly before and during the race helps you maintain energy, prevent blood sugar crashes, avoid GI distress and cross the finish line strong, instead of struggling through the final miles or ending up in the porta potty wondering what the heck just happened.

In today’s post, we’ll break down nutrition for a triathlon so you can show up to your Ironman 70.3 with confidence in your plan and ready to power through from start to finish.

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The Role of Triathlon Nutrition in an Ironman 70.3 Race

Training and racing an Ironman 70.3 demands a ton of energy. Not only does it take energy to power through your workouts, but it also requires plenty of energy to recover from them. Because of these high demands, athletes are at risk of underfueling if they don’t follow a structured triathlete diet, one that focuses on nutrition optimization, not restriction! 

Signs of underfueling to be on the look out for:

• Low energy during the day and/or during workouts 
• Cravings and overeating at night 
• Hitting the wall or bonking during long workouts and races
• Stuck in a plateau with your training
• Thinking about food 24/7
• Feeling hungry all the time
• Poor exercise recovery
• Irregular period or loss of period in female athletes
• Frequent illness and injury

Additional challenges often come into play like “hitting the wall” or “bonking” and experiencing GI issues. That’s why creating a triathlon nutrition plan, practicing it during training and adjusting as needed is essential for performance, confidence and comfort on race day.

The goals of nutrition for triathletes racing a 70.3 are simple but crucial:

• Optimized your glycogen stores going into race day
• Maintain steady energy throughout the race with proper fueling
• Meet hydration and electrolyte needs to support hydration status and performance

Next, let’s talk about what to eat in the days leading up to your race, on race morning and during the race itself.

Pre-Race Nutrition

Race Week

During the 3 days leading up to your race, carb load to optimize your glycogen (energy) stores. When done correctly, this triathlon training nutrition approach combined with smart race day fueling, can reduce your risk of hitting the wall, improve performance and even help you shave valuable minutes off your finish time.

Aim for 3 carb-rich meals per day, 2 carb-rich snacks and include liquid carbs as needed to reach your target of 8-12 grams of carbs per kilogram of body weight per day. For meal inspiration, check out my post on 10 Easy Carb Loading Meals for Race Day Success.

In addition to fueling, prioritize hydration throughout race week and aim for at least 8 hours of sleep per night. Proper rest and hydration will help you feel recovered, energized and ready to perform on race morning.

The Night Before the Race 

For dinner, focus on a carb-rich meal to help you top off your glycogen stores. Good options include pasta, rice dishes or a potato-based meal paired with some protein and maybe a small amount of color (fruit/veg). As a heavy, salty sweater, I personally like to add a sodium and carb-rich sports drink such as Skratch Labs Sport or BPN G1M drink mixes. 

At dinner, eat until you’re comfortable satisfied, there is no need to overdo it. Stuffing yourself can backfire and leave you dealing with GI discomfort on race day.

It’s also smart to avoid certain foods the night before your race, including high-fiber choices (like chickpea pasta), high fat or fried foods, spicy dishes and anything you know doesn’t sit well with you.

The Morning of the Race 

Just like dinner the night before, your breakfast on race morning should be carb-rich. Aim for at least 2-3 g of carbs per kg of body weight, paired with a small amount of protein and minimal fat and fiber. For example, a 70 kg athlete would target around 140-210 g of carbs before the race. Don’t forget to hydrate well, and consider including a sports drink that contains both carbs and sodium.

Timing is key. Give yourself at least 2-3 hours to digest your breakfast when consuming a larger carb meal. Everyone’s digestion is different, so use your training to figure out what timing works best for you.

About 30-60 minutes before the start, have a small, easily digestible carb snack like an energy gel, a few graham crackers or a fruit pouch and a few sips of sports drink. This helps top off your energy stores and sets you up for a strong swim.

During Race Triathlon Nutrition

Swim

There’s no opportunity to fuel or hydrate during the swim, so how you fuel and hydrate beforehand is critical. Make sure you have a solid breakfast and snack planned using the tips above.

Bike

When transitioning from the swim to the bike, you can choose to take in some fuel and hydration at that time or start once you’re on the bike. I’ve had clients take advantage of their transitions by fueling and hydrating during that time but find what routine works best for you.

Even if you don’t feel hungry immediately after the swim, being proactive with both fueling and hydration is key for maintaining performance throughout the race. You don’t want to fuel during the race based on hunger.

During the bike, aim for:

• Carbs: 60-90+ g per hour
  
• Fluids: 14-27 oz per hour
  
• Sodium: 300-1000+ mg per hour
  

Fluid and electrolyte needs are highly individual and the above are general sports nutrition recommendations. To really dial in your hydration strategy, consider a sweat test to personalize your triathlete nutrition plan. Even mild dehydration can start to impair performance. 

Prep your bottles and anything you need to ahead of time. Decide where you’ll store your fuel and hydration on the bike so it’s easily accessible. Experiment with this setup during training to find what works best.

Below is an affiliate link, which means I may earn a commission if you purchase—at no extra cost to you.

hDrop which is a reusable sweat test that I personally used when I was training for the NYC Marathon. It helped me identify my personal needs and I was able to create a very specific hydration and electrolyte plan for my training and my race.

Run

Your nutrition needs during the run are similar to the bike, but the key difference is how you carry your fuel and hydration. Decide whether you’ll rely on aid stations, carry your own, or use a combination. Prep ahead of time by premixing bottles, laying out your fuel and practicing your method during long runs to ensure it’s comfortable and effective.

Common Triathlon Nutrition Mistakes to Avoid

Even with the best training, simple fueling mistakes can quickly derail your race.

1. Skipping breakfast or undereating 

Starting the race on low or empty can leave you struggling from the very beginning. Avoid this by practicing your pre-race breakfast during training and gradually building up to your fueling goals. Remember that it can take time to train your gut.

2. Drinking too much plain water without electrolytes 

Hydration is so much more than drinking plain water. Electrolytes are crucial to prevent imbalances and reduce the risk of exercise-associated hyponatremia. Make sure your fluids include sodium, especially on hot or long workouts and on race day. 

3. Trying new products on race day 

Race day is not the time to experiment. Stick with the fuel and sports products you’ve used during training and know what’s available on course if you plan to rely on aid stations. Practicing with your chosen products helps avoid surprises like GI issues during the race.

4. Waiting too long to fuel and hydrate during the race 

Don’t wait until you feel depleted or extremely thirsty to start taking in fuel and hydration. Once your body is in deficit, it’s difficult to recover energy or hydration mid-race. Stay proactive from the start to maintain steady performance.

Practice Makes for a Smooth Race Day 

Use your long training sessions to practice your triathlon nutrition plan and gradually build up to your fueling and hydration goals over time.

Race simulations are especially valuable because they give you a chance to rehearse your exact race day nutrition plan. By fine tuning your strategy and training your gut ahead of time, you’ll be able to tolerate higher amounts of carbs and fluids, hit your goals and perform at your best on race day without complications.

Conclusion

A huge part of nailing your Ironman 70.3 race is nailing your nutrition and hydration. Plan ahead, practice your race day plan and fine tune your strategy so you can maintain energy, prevent GI issues and race strong. 

Remember that nutrition is highly individualized and your nutrition needs are unique so use your long training sessions to find what works best for you. Show up on race day feeling confident in your nutrition plan, trusting your training and letting your fueling strategy help you power through the race, from start to finish. 

If you’re looking for a personalized triathlon food plan or racing nutrition plan, check out my 1:1 Nutrition Coaching Program and apply here!