How to Fuel Your Triathlon Training


How to Fuel Your Triathlon Training

Triathlon is an endurance sport that demands a lot from its athletes, requiring a combination of physical strength, mental toughness, and careful preparation. While many athletes focus on training their bodies for the physical demands of a triathlon, proper nutrition can make all the difference in the outcome of the race. 

Delving deeper, we’ve recruited the expertise of Rachael Butcher, Head of Nutrition at Natural Fitness Food, who shares her expert insights on the best practices for triathlon nutrition, including pre-, during-, and post-event nutrition strategies. Whether you are a seasoned triathlete or just starting out, Rachel’s advice will provide valuable guidance on how to fuel your body for optimal performance and recovery. 

“Whether you are eating for Ironman or your first sprint race, the golden rule is don’t do anything new on race day,” says Butcher. “That includes pre-race. What works for one person might not be the best strategy for you. Come race day you can enjoy your pre-race meal knowing it will provide you all the calories you need without risking any digestive issues or upset stomach.”

Things to remember on race day:

You have around a 2-hour fuel reserve – your body predominantly uses fat as fuel during endurance training and events. However, that fat is used in light of carbohydrates, i.e. your body needs to burn carbs to utilise the fat as fuel. Your body’s primary sources of carbohydrates are:

  • Glycogen stored in muscle and liver
  • Food or sugars taken on during exercise

A well-trained endurance athlete has around 1,500-2,000 calories of glycogen stored which provides fuel for 1¾ to 2½ hours of exercise.

Less is sometimes more: when you are not exercising i.e. you’re sat still, your body can relatively easily process that entire pizza or in this instance, highly concentrated sports gel, but the harder you exercise the scarcer resources become for processing food, as blood is shunted from the stomach to the hard-working limbs.

“The fewer calories you eat and ask your body to process during a race, the more resources your body has available to push hard through your swim/bike/run,” explains Butcher. “Therefore, the best strategy for short course races is to take on as few calories as is needed.”

On race day be sure to: 

  • Stay well-hydrated
  • If it’s a warm day, that you’ve pre-loaded with sodium
  • Top up your glycogen stores
  • Do your best to empty your stomach and digestive tract

Before the race 

“Consider making lunch your largest meal the day before the race. No need to opt for anything particularly specialist here, pasta or sandwiches are absolutely fine but opt for more fuel at lunchtime and a lighter dinner,” says Butcher.

“If you’re preparing food at home, be sure to include a light seasoning of salt. Drink water all day, if it’s hot or you have a high sweat rate you might want to include a sports drink, or make your own from fruit juice, water and a pinch of salt. Make dinner light, high in carbs and easy to digest.”

Fuelling on race day

“What you take on during your race will depend on the distance you’re covering: these guidelines will cover sprint and Olympic-distance racing.”



“For races up to an hour in duration, the focus should be hydration – small sips, often. If you feel low on energy on the run, a glucose tablet or energy chew can boost your blood sugar.”

“If you’re racing closer to 90 minutes, hydration is still the main focus, but look to top up with carbohydrates for the last half of the race; it may be a chew at the second transition and a few sips of energy drink every 15 minutes.”

“This is about boosting blood glucose rather than considering taking on calories or grams of carbohydrate per hour.” The bottom line, says Butcher, is that you don’t need to take in any calories here, the fewer you take in the harder you can race. If you choose to take any in, ensure it’s no more than 100-200 calories across the whole event.”



“Once the swim is done, focus on hydration with small sips, then aim to eat 200-300 calories of food per hour. Good options include energy chews/blocks or small bites of energy bars. Stay focused on hydration, aiming for 5 to 10 ml per kg of body weight,” says Butcher. “Whatever you opt for, make sure it’s easy to digest and won’t lead to dramatic blood sugar fluctuations, and be sure to have tested it in training.” 

On the run, it’s about keeping blood sugar up to maintain pace and prevent dips in energy, Butcher explains. This can include energy chews, jelly babies and glucose tablets are all good options here. “Again, the less you eat, the fewer additional tasks you give your body to do, which again means you can go harder with reduced risk of issues such as cramping and stitches,” she explains. “For all distances, the number one rule is to practice and hone your fuelling plan in training to set yourself up for fuelling success come race day.” 

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