Triathlon nutrition: the complete guide to performing without digestive problems

It's often said that triathlon is a sport for "triathletes." That's wrong. It's a sport for "quadriathletes." The fourth discipline, the one that can tip the balance between a personal triumph and an endless ordeal, is nutrition.

You can have the best carbon bike and legs of fire, but if your tank is empty or your digestive system says "stop" at the 5-kilometer mark of the run, the finish line will remain a mirage.

Here's how to transform your triathlon nutrition into your best ally, from the days before the race to the finish line, with a natural approach.

Daily nutrition for triathletes: building performance

There's no point in stuffing yourself with pasta the night before if you eat whatever you want the rest of the year. Performance is prepared months in advance.

Taming your blood sugar

The classic mistake? Overusing simple sugars during training. To avoid energy crashes, prioritize foods that... A low or moderate glycemic index (GI) diet is recommended. Replace white bread, regular pasta, and white rice with sweet potatoes, quinoa, buckwheat, and legumes (lentils, chickpeas). This helps train your body to use fat more efficiently as fuel, a crucial skill for long-duration efforts.

Proteins and lipids: the unsung heroes

Protein is essential for repairing muscle fibers after your (very strenuous) running sessions. Aim for about 1.5g per kilogram of body weight. Healthy fats ( Omega-3s ) such as rapeseed oil, walnuts, and small oily fish are your best natural anti-inflammatories for protecting your joints.

Nutrition the week before a triathlon: replenishing energy stores without disrupting digestion

The goal of this phase is not to gain weight, but to saturate your glycogen stores (the sugar stored in your muscles and liver).

Timing	Focus	Practical advice
7 to 4 days before departure	Stabilization	Eat a balanced diet. Don't try any new foods that week.
3 days to 1 day before departure	The carbohydrate load	Increase your portions of starchy foods (rice, semi-wholemeal pasta) by about 20-30%.
The last day	Digestive comfort	Avoid irritating fibers (cabbage, peppers), overly fatty foods and strong spices.

If you struggle to eat large quantities, energy bars are perfect as a snack. Opt for natural recipes that are easy to digest and allow you to replenish your sugar stores without feeling heavy.

Nutrition in triathlon according to race format

Not all triathlons are created equal when it comes to nutrition. The duration of the effort completely dictates the strategy.

Triathlon Sprint / S (≤ 1h15)
Internal reserves are generally sufficient. A drink beforehand, good hydration, and possibly a gel at the end of the bike ride are more than enough.

Triathlon M (1h30 to 3h)
Carbohydrate intake becomes essential, especially on the bike. Target: 40 to 60g of carbohydrates per hour, in the form of gels, fruit compotes or isotonic sports drinks.

Long Distance Triathlon / Ironman
Nutrition becomes central. You should aim for 60 to 90g of carbohydrates per hour, intelligently distributed between solid (cycling), semi-liquid and liquid, while ensuring hydration and electrolytes.

Recommended intake during a triathlon

Triathlon nutrition on race day: hour-by-hour strategy

Breakfast (H-3)

Eat 3 hours before departure. This is the time needed for your blood to leave your stomach and go to your muscles.

• The typical menu: An effort cake, a ripe banana or a few slices of white bread with honey.

• To avoid: Very strong coffee (accelerates transit), acidic orange juice and dairy products if you are sensitive to them.

The waiting ration (H-1)

The stress of setting off drains your energy. Drink a few sips of water or have an energy compote 30 minutes before jumping in. It's light, won't upset your stomach, and will help stabilize your blood sugar.

Nutrition during a triathlon: cycling vs running

Each segment has its own constraints.

Cycling: the "kitchen" of your race

This is the only time your digestive system can tolerate solid food because the body is supported (no impact). Aim for 60 to 90g of carbohydrates per hour for a Long Distance (L, XL) race, and 40 to 60g for an M race.

Alternate between tasty energy bars (it helps keep morale up and avoids nausea) and sources of liquid carbohydrates such as energy gels or fruit compotes, especially just before a difficult climb like a mountain pass or a steep hill.

Running: Beware of sensitive areas

As soon as exertion begins, the body prioritizes supplying oxygen to the muscles and regulating body temperature. To achieve this, it reduces blood flow to functions deemed secondary at that moment, particularly the stomach and intestines. Intestinal blood flow can thus decrease by up to 80%.

The digestive process is significantly slowed down, or even stopped. Food can then accumulate in the stomach, causing feelings of heaviness or nausea, or it may no longer be properly absorbed in the intestines, leading to problems such as diarrhea.

The impacts with the ground amplify the phenomenon. Your stomach is churned. This is where gastric problems often arise.

Switch to liquid/semi-solid. Energy gels and compotes are your best friends.

For athletes with sensitive stomachs, it is recommended to consume gels or fruit purees in several doses. Mulebar gels are the only ones packaged in truly resealable tubes, like toothpaste. You can take a small dose of gel every 15 hours with a little water and close the tube. No need to swallow it all at once!

This avoids the "yo-yo" effect and blood sugar spikes that can cause the "cotton leg" syndrome, where the legs feel weak and unable to support you.

Hydration in triathlon: water, electrolytes or sports drink?

A 2% loss of your body weight in water would equate to a 20% decrease in your performance.

During the cycling and running portions of a triathlon, hydration drinks play a key role for Maintaining fluid and electrolyte balance: they compensate for water and mineral losses due to perspiration, limit dehydration, and help prevent cramps, without overloading the stomach. You lose sodium through sweat. Without it, you risk cramps.

Conversely, a sports drink provides additional energy-boosting carbohydrates, essential when intensity and duration increase, to support endurance and delay fatigue. The right choice therefore depends on the stage of the race: simple hydration when energy intake is ensured elsewhere (gels, fruit compotes, bars), and a sports drink when energy and hydration need to be met simultaneously, while remaining isotonic for easy digestion.

Drink 2 to 3 sips every 15 minutes, even if you're not thirsty. If you're exercising for more than 2 hours, an electrolyte drink is essential.

Nutrition after a triathlon: optimizing recovery

As soon as you cross the finish line, your body begins to repair itself. The following 30 minutes are crucial; this is called the metabolic window.

This is the post-race period, during which it is necessary to

• Rehydrate . Drink water rich in bicarbonates (like St-Yorre) to "buffer" the acidity produced by exertion.
• Repairing broken muscle fibers by consuming protein.
• Replenish glycogen stores by consuming some carbohydrates.

Triathlon nutrition: common mistakes to avoid

Here are some of the most common nutritional mistakes in triathlon:

• Testing a new product on race day

• Consuming too much fiber or fat before departure

• Drink only water without electrolytes

• Swallowing an entire gel in one go while running

• Neglecting hydration right from the start of cycling

These errors are responsible for the majority of dropouts related to digestive problems or bouts of fatigue.

Nutrition isn't something you can just wing. Test your fueling strategies during training, learn what works for you, and remember that the pleasure of good food is also a brain booster. Mental strength always kicks in when your body falters. Good luck with your race!

 

FAQ – Triathlon Nutrition

What is the best breakfast before a triathlon?

A meal rich in simple carbohydrates and low in fiber: homemade energy cake, rice pudding, or white bread. The goal is to replenish energy stores without putting a strain on the digestive system.

How to avoid getting a stomach ache while running?

The stomach receives less blood during exercise. Avoid overly chemical products with preservatives. 100% natural products like those from Mulebar are much better tolerated because they contain no "mystery" ingredients.

Do you need to eat during a sprint triathlon?

For an effort lasting less than an hour, your energy reserves are sufficient. A drink beforehand and a gel just before the end of the ride will be more than enough.

How many carbohydrates per hour in a triathlon?

Between 40 and 60g/h on an M format, up to 90g/h on an Ironman, provided you are trained digestively for it.

How many gels should I bring for an Ironman?

It varies from person to person, but the average is around 20 to 25 units if that's all you consume. The trick is to alternate with solid food while cycling to avoid overwhelming your palate.

Should you eat while swimming?

Not only ducks can do it! On the other hand, a well-thought-out diet before the race allows you to arrive on the bike with stable blood sugar levels.

Why choose Mulebar for your next triathlon?

At Mulebar, we come from the field. We know what it's like to have your heart racing at 170 beats per minute and trying to open an impossible package or swallow a gel that tastes like medicine.

• 100% Natural Ingredients: No artificial flavors, no preservatives. We use real fruit, real grains, brown rice syrup, agave syrup...

• Zero waste (or almost): Thanks to our eco-refills, you can refill your reusable gel tubes or our silicone bottles. It's better for the planet and for your swimsuit pockets, which will no longer stick.

• Digestibility: It's our obsession. By sticking to natural ingredients, we eliminate 90% of the causes of gastric problems during races.