Here's how to successfully fuel your triathlon training.

What you eat and your fueling strategy matter just as much as your swim, bike, and run training sessions when training for a triathlon.

When you get your nutrition correct, you’ll have more energy for training, will recover faster between sessions, and perform better to help you improve rapidly.

This blog post explains what your diet should look like when training for a triathlon to help you perform and reach your potential.

What you will learn:

  • What to eat when training for a triathlon

  • How to design a triathlon nutrition plan for training success

  • The importance of carbohydrate intake is important for endurance athletes

  • What to eat on the day of your triathlon (a few bonus tips for success)

What should I eat when training for a triathlon?

“Triathlon nutrition isn’t just about race day — it’s a daily practice that supports your training, recovery, and performance,” says Alex Larson, a registered dietitian and triathlete.

She explains how most triathletes do best with structured eating, 3-4 meals/day.

Here’s a macro split for triathlon training provided by Larson:

  • Carbohydrates (45-60%)

  • Protein (20-25%)

  • Fats (20-30%)

1. Carbohydrates

Carbohydrates are fuel — it’s what gives you energy.

As a general rule of thumb, you want carbs before and after exercise.

For exercise that lasts longer than 75 minutes, you want carbs during.

And you want to eat more carbs the evening before a long workout.

2. Protein

Aim for a minimum of 1.2 to 2 grams (g) of protein per kilogram (kg) a day, as suggested by the ACSM.

Try to divide your protein intake into 3-5 servings.

This might include three meals — breakfast, lunch, and dinner — and two snacks.

When you spread your protein intake out evenly, your body remains in a net positive protein balance, which helps keep you in an overall positive nitrogen balance. This helps maximise recovery and encourages better training adaptations. 

Additionally, avoid eating too much protein before exercise because this slows digestion and may cause cramping.

3. Fats

You want between 20% and 30% of your total calories from fats.

Healthy fats include olive oil, avocado, full-fat yoghurt, fatty fish, flaxseeds, dark chocolate, butter, cheese, and eggs.

Fats play an essential role in hormone production. This can influence recovery, energy levels, and training adaptations. Also, healthy fats like Omega-3 fatty acids from oily fish — salmon and canned tuna — can help reduce inflammation and boost immune function.

Avoid eating too much fat before exercise, which may cause digestive discomfort.

4. Micronutrients — fruit and vegetables

Just because micronutrients are not mentioned in the macro breakdown above, it does not mean they are not important, especially for endurance athletes.

Eat plenty of fruit and vegetables, ideally eating a variety of colours.

These provide essential micronutrients for everything from energy production to immune support and enzyme activity. In other words: eat your greens. They’re a reason five a day exists.

How to fuel your training sessions

While having a general idea of how many of each macronutrient to eat, Larson explains how you don’t want to obsess over the exact split, and instead focus on building meals that match your training load.

“High volume and more intense training days will require more carbs and overall energy. Rest days can focus on a more balanced meal, prioritising a higher protein intake to support muscle recovery.”

By fueling your body for the demands of training, you’ll give your body plenty of energy and the nutrients it needs to perform and recover properly.

I will now break down what to eat depending on how long a training session you have planned.

< 75 minutes 

“A small carb-rich snack beforehand (like toast with jam or a banana) is helpful if you’re training fasted or in the morning. 

For shorter workouts, recommendations are 0-30 grams of carbohydrates. However, for higher intensity training sessions, it may be worth fueling more to help you finish the workout strong and not go into the rest of the day depleted and behind on energy,” says Larson.

This is even more important if you plan on training again later in the day.

75 minutes - 2.5 hours

For longer sessions, you will want to eat during your session.

This ensures your glycogen stores remain topped up to give you energy and helps reduce the likelihood of you hitting the wall — this is when you run out of energy, and it’s very difficult to continue.

“Aim for 30-60 grams of carbs per hour. This could be a sports drink, energy chews, or gels. For example, a long bike ride or brick workout is a good time to practice race-day fueling.”

GEL50 contains 50g of carbohydrates to fuel performance and gives a quick mid-ride energy boost.

2.5 + hours 

Larson recommends 60-90g of carbs per hour for longer sessions. “Fuel early and consistently to prevent bonking. The bike is a great place to take in more fuel since it’s easier to eat and digest than during a run.

Train your gut! Practice with the same products and timing that you’ll use on race day.”

How many calories should a triathlete eat per day?

Your calorie needs will vary depending on your body weight, activity level, and body composition goals.

For example, on days where you have a 3-hour bike ride or a swim and a run, you will need more calories than a single session or a recovery day.

A good place to start is by eating anywhere from 2,500 - 3,000 calories.

Fuel for performance.

To dial in your nutrition, it’s a good idea to weigh yourself often — always in the same conditions. It’s best to weigh yourself first thing in the morning after using the bathroom in the nude.

Tracking your weight can help you better understand your calorie needs and adaptation to training. For example, you may realise you are underfed, resulting in a drop in training quality or generalised fatigue. Use body weight as a tool to help you adjust your calorie intake as needed.

What should I eat on the day of a triathlon?

What to eat depends on the race distance and the individual athlete. But the main priority is your carbohydrate intake, fluids, and electrolytes.

Larson breaks down each triathlon event below with guidelines on how to fuel for success:

“Sprint distance: Fuel is optional but helpful — take in 30 to 60g carbs (like one gel or some sports drink) on the bike if the race lasts over an hour. The main priority is hydration, and if the race is especially hot and/or humid, consider including electrolytes.

Olympic distance: Aim for 30 to 60g carbs per hour. The bulk of your fueling will happen on the bike — gels, chews, and a carb-rich drink are great. You may need one more gel on the run.

70.3 distance: Target 60 to 90g+ carbs per hour, and start early with fluids and fuel. Carb hydration mixes in your bottles on the bike work very well. Use a mix of solid and liquid fuel if it works for your gut. Include electrolytes too, especially in the heat.

Full 140.6 distances: You’ll need a full fueling strategy. Plan 60 to 90+ g carbs per hour, including sodium/electrolytes.

I have two mantras for long-distance triathletes: "The bike is the buffet," and "Eat before you're hungry, drink before you're thirsty." Because once you get behind on fuel and fluids, it's hard to catch up. Be strategic in how you can easily keep up on nutrition throughout every hour of the race.

Hydration matters just as much. Sip fluids steadily, especially in hot/humid conditions, and adjust electrolytes based on your sweat rate.”

What to eat after a triathlon

After a triathlon, aim to refuel within 30 to 60 minutes.

You don’t need to eat a full meal — you will likely struggle to eat this much food. A recovery bar like BAR+ contains 45g of carbs and 15g of protein to kickstart the recovery process.

Later, aim for a balanced meal with:

  • Carbs to replenish glycogen stores

  • Protein to support muscle repair

  • Fluids and electrolytes to rehydrate

Key takeaways

  • Proper nutrition for triathlon supports your training, recovery, and performance

  • Fuel for your training load and give your body the nutrients it needs

  • The longer your workout, the more carbohydrates you’ll need before (and during) to have enough energy

  • Practice your race day nutrition on those longer training sessions

  • Consider electrolytes to achieve proper hydration

FAQs

Do triathletes drink protein shakes?

Yes — many do, especially after training sessions. They’re a quick and convenient way to hit your protein targets, particularly if you’re training twice a day. Just make sure your shake also includes carbs if it’s your main recovery meal. Alternative options include recovery bars or a protein shake, and a banana. 

What is the best diet for triathletes?

The best diet for triathletes is tailored to their training needs and energy demands. You should eat more carbs for longer sessions and prioritise carbs and protein after a workout to improve your recovery.

What is the best breakfast for triathletes? 

There is no best breakfast, but some ideas include a bagel with a banana and peanut butter or a bowl of oatmeal with honey.