Triathlon Nutrition

Between swimming, running, biking, strength training, stretching, and brick workouts, there’s a lot that goes into a triathlon training plan. Unfortunately, with so much time and energy invested into staying in peak shape as a multi-sport athlete, it can be easy to overlook nutrition and the important role it plays in achieving your goals as a triathlete. On top of that, nutrition misinformation can lead even the triathletes who are prioritizing nutrition down a path that actually harms their performance. In this post we’ll cover the basics of triathlon nutrition, including common nutrition issues triathletes face, what to eat before, during, and after a workout, and how to optimize nutrition for performance on race day.

Common Triathlon Nutrition Issues

Because triathlon training and competition is so taxing on the body, proper nutrition is essential not only to fuel your performance but also to facilitate recovery. A few nutrition issues that commonly come up for triathletes include underfueling, dehydration, and GI distress.


Not eating enough to support your activity level (also known as low energy availability) can lead to not only the dreaded bonk, but also to a wide range of long-term consequences for mental health, physical health, and performance including:

  • Increased injury risk
  • Decreased glycogen (the carbs stored in your body that fuel your workouts)
  • Irritability, anxiety, and depression
  • Poor bone health
  • Gastrointestinal, cardiovascular, and menstrual dysfunction
  • Decreased muscle strength and endurance performance

triathlon nutrition underfueling

Because of the high energy output associated with triathlon training, underfueling can easily occur unintentionally, which is why prioritizing adequate intake on a day-to-day basis is essential. Additionally, a heightened focus on “race weight” can trigger disordered eating and/or chronic underfueling. To learn more about how restrictive diets can harm performance and health, check out this post on Ditching The Diet Mentality for Performance.


With any form of endurance training comes an increased risk of dehydration, and if you’re training in a hot environment, that risk is even higher. Maintaining adequate hydration status is critical not only for your general health and well being, but also for maximizing physical performance. 

When thinking about the role of hydration in your triathlon nutrition plan, relying on thirst alone isn’t going to cut it. Thirst is less sensitive when you exercise and won’t kick in until you’ve lost 1-2% of your body weight in fluid, at which point, you’ll already be experiencing a decline in aerobic performance ability, a decrease in blood volume, and difficulty releasing heat through sweat (since you don’t have as much fluid to lose). On top of that, drinking just enough water to quench your thirst isn’t enough to completely rehydrate you. In light of this, it’s essential for athletes to anticipate their thirst by staying hydrated throughout the day, keeping plenty of fluids on hand during a workout, and replenishing post-workout. An easy way to assess your hydration status is to make sure that the color of your pee stays relatively light or pale yellow.

hydration for triathlon

To ensure optimal hydration, be sure to replace not only water, but also the electrolytes lost through sweat. Sodium is lost in the greatest amount, but other electrolytes including potassium, magnesium, and calcium are lost in sweat in smaller amounts, too. Consuming adequate carbohydrate is also important for proper hydration, since each gram of carbohydrate stored in the body holds on to 3 ml of fluid. Sports drink powders from brands like Skratch and Clif provide both carbs and electrolytes that can help you avoid dehydration and its symptoms. Nuun and Now make hydration supplements that provide only electrolytes, which can be a good option if you are ingesting easily digestible carbs along with it, like in this Electrolyte Recovery Smoothie recipe. Some additional tips for hydration are included in the graphic above – and if you’re training with long duration and/or high intensity, these apply year-round, not just in the summer!

GI distress

There’s nothing worse than setting out for a hard training session or race and finding yourself crippled by gastrointestinal (GI) symptoms like abdominal pain and cramping, nausea, bloating, vomiting, and diarrhea. GI distress is a common issue for triathletes, but fortunately, playing around with what and when you eat before your workouts can be extremely beneficial in managing and preventing GI symptoms. In the next section, we’ll cover how to build pre- and intra-workout fueling into your triathlon nutrition plan as well as how to train your gut to avoid stomach discomfort.

What to Eat Before, During, and After Triathlon Training

Now that you’re aware of some of the most common triathlon nutrition issues, let’s dive into some specific considerations and examples for pre-, intra-, and post-workout fuel. We’ll focus on food here, but fluids and electrolytes are also important at all three of these stages to maintain hydration status.

Pre-workout triathlon nutrition

Since carbohydrates are the most efficient source of energy for your muscles during a training session, you’ll want to consume plenty of easily digestible carbs pre-workout. Foods high in fat, fiber, and protein, on the other hand, are an important part of your daily diet but take longer to digest and may cause some GI distress if consumed in large amounts too close to a workout. 

In addition to your macronutrient balance, the timing of your pre-workout fuel is also critical when it comes to optimizing energy levels and avoiding GI symptoms. If you’re planning on eating a full meal pre-workout, do so at least 3 hours before you head out to give your body time to digest. About an hour before you train, consider topping off your energy stores with a carbohydrate-rich snack that’s lower in fat, fiber, and protein. If you’re less than 30 minutes away from your workout time, you’ll want to opt for simple carbs only.

energy balls pre-workout snack

Here are some pre-workout meal and snack ideas that put these tips into practice. Keep in mind that energy needs and digestion time vary from person to person, so there will be some degree of trial and error to determine what works best for your individual triathlon nutrition plan. Additionally, the optimal timing for pre-workout fuel may differ depending on the sport. For example, you may find that a snack consumed an hour in advance sits fine with you on the bike but that you require more digestion time before a swim workout.

  • 3-4 hours before a workout: Eat a meal that includes carbohydrate-rich foods paired with moderate amounts of fat, fiber, and protein. Some examples include eggs with toast, a pesto grain bowl, or a tuna sandwich. Serve these items with carbohydrate-rich sides like fruit, crackers, or a glass of soy or dairy milk.
  • 60-90 mins before a workout: Choose a carbohydrate-rich snack with a bit of protein or fat, like a banana with nut butter, pita with hummus, or homemade snack bites.
  • <30 mins before a workout: Stick to simple carbs like 100% fruit juice, a honey packet, or a sports gel for easy digestion.

Intra-workout triathlon nutrition

Decades of sports nutrition research shows that consumption of carbohydrates during endurance exercise is linked with enhanced performance. Based on the available evidence, the Academy of Nutrition & Dietetics position paper on nutrition for athletic performance recommends 30-60g carbohydrate per hour of endurance exercise and up to 90g per hour during ultra-endurance activities lasting more than 2.5-3 hours. This is in addition to consuming a carbohydrate-rich snack pre-workout.

Some products that can help you meet your intra-fueling needs include: 

If you’re not used to fueling during your workouts, build up slowly to meet the recommendations. If you go from consuming nothing at all during workouts to consuming 60 grams of carbs per hour of activity, you may experience GI discomfort — this doesn’t mean that you can’t tolerate intra-workout fuel, but rather that your body needs time to adjust. Carbs are essential for optimal triathlon nutrition, so if you’re struggling to incorporate them during your workout, check out our post on Training Your Gut for Athletic Performance and the graphic below for some practical strategies.

training your gut for endurance exercise

Post-workout triathlon nutrition

The macronutrients to prioritize post-workout are protein for muscle repair and carbohydrates to refuel you. The recommendation for post-workout protein consumption varies according to body size and composition, but around 20 grams is a good frame of reference. If you want a more precise estimate, use the range 0.25-0.3 grams per kilogram of body weight. 

Pairing carbohydrates with protein will help your body properly recover and refuel for your next workout. Carbs also serve a protein-sparing function, meaning that by providing your cells with the energy they need, they enable protein to be used for muscle synthesis and repair rather than for energy.

Ideally, you’ll start refueling within 1 hour of finishing your workout. Here are some post-workout snack ideas that will help you get protein and carbs in quickly and tide you over to your next meal: 

If you find that your appetite is suppressed after workouts, try a smoothie — it’s a great way to consume the nutrients you need post-workout in a format that may be easier to get down. The graphic below from our sister site Student Athlete Nutrition shows the components of a balanced post-workout smoothie.

post-workout smoothie

If you’re hungry for a meal post-workout and have time to make one right away, you can always jump straight to that, too! Here are some recipes that provide plenty of protein and carbs:

Race Day Nutrition for Triathletes


All of the triathlon nutrition considerations discussed above apply on race day, too, but the most important thing is to stick to familiar foods that you know you tolerate well. If you usually have oatmeal before morning training sessions, stick to oatmeal —  race day is NOT the time to try something new. 

If you don’t usually train early in the morning, you may find it helpful to practice doing a high-intensity morning workout a couple of times in the weeks leading up to the race. You can use these training sessions to see how your body responds to different fueling strategies first thing in the morning and see what works best for you. Some ideas for pre-competition breakfasts that tend to be well tolerated are shown in the graphic below. 

race day breakfast triathlon

Intra-race fueling & hydration

The same advice goes for fueling during your race — stick to sports fueling products you know you tolerate well, and practice using them in your training sessions. See the section above on intra-workout fueling for guidance on how much carbohydrate you should be taking in based on the expected duration of your race. 

intra-race fueling triathlon

Be sure to have a plan for both hydration and fueling. Position water bottles on your bike in advance and decide how you will store any sports gels, chews, or bars during the race. Many athletes tape their fuel to the frame of their bike or use the pockets in their triathlon kit. You may also consider getting a fueling/hydration belt for longer races if you don’t want to rely solely on aid stations for water during the run. If the race is in a hotter climate than you are used to, you will need extra fluids and electrolytes to compensate for increased sweat losses.

Carb loading

What about the night before the race? Is carb loading necessary? Should you eat pasta and nothing else the night before? Yes and no. You’ll want to eat a carbohydrate-rich meal the night before a race, but it’s not necessary to eat exclusively carbs. Balance out your plate with a bit of protein and fat, too. 

carbohydrate loading

Additionally, consider upping your carb intake for 2-3 days before your race, not just the night before. Research indicates that consuming 10-12 g/kg/day carbohydrate for the 48 hours leading up to a race may improve performance, particularly for longer distance races that last 90 minutes or more (think Olympic distance triathlons, Half Ironmans, and Ironmans). This would equate to roughly 750 grams of carbohydrate per day for an athlete who weighs 150 lbs and roughly 1,250 grams of carbohydrate for an athlete who weighs 250 lbs. For reference, an apple or banana contains around 25 grams of carbohydrate, two slices of bread contains around 30 grams of carbohydrate, and a cup of cooked grain contains around 50 grams of carbohydrate. By incorporating extra carbohydrate into your triathlon nutrition plan in the days leading up to the race, you are maximizing the amount of carbohydrate stored in your muscles as glycogen, which will benefit your energy levels during the race. Additionally, carbohydrate loading enhances hydration, since glycogen holds water in the body.

Keep in mind that the type of carbs matters, too. The cliche of eating pasta is on the right track since pasta provides simple carbohydrates that are easily digestible. Rice, bread, tortillas, fruit, oats, and potatoes are also great options for carb loading. Avoid very high fiber sources of carbohydrate like beans, lentils, and cruciferous vegetables that may put excess stress on your GI tract leading up to the race. Pairing carbs with rich foods like cream sauces or deep fried items may also be taxing on the GI system the day before a race, so stick to simple sides and sauces.

Triathlon Nutrition: Key Takeaways

Triathlon is an intense sport both physically and mentally, and consuming adequate energy through balanced meals and snacks is essential to optimize performance. Nutrition needs are nuanced and highly individualized, but here are some key takeaways:

  • Underfueling, dehydration, and GI distress are some of the most common nutrition issues triathletes face, but can be avoided with careful planning.
  • Focus on carbs for fuel immediately before and during a workout and carbs + protein for recovery after a workout. At all other meals and snacks, consume a balance of protein, carbs, fat, and fiber.
  • Stick to familiar foods on race day, and consider increasing carb intake for 2-3 days beforehand to top off energy stores.

Need support creating an individualized triathlon nutrition plan? We’d love to help! Learn more about our 1-1 nutrition coaching services here.

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