Triathlon Race-Day Nutrition

18th September 2023


My favourite sport to compete in (and watch) in the Summer months is triathlons - I love the variety of different sports all in one race, definitely entertaining and always a good challenge. Every year I see plenty of clients try out the Corporate Triathlon Series and have a great time with their work mates and then many get hooked and head onto do more triathlon races.

While the variety of sports in a triathlon makes it super fun to compete in, it also puts a lot of demand on the body nutrition-wise. If you have a goal of doing a triathlon, below are some nutrition tips to help fuel yourself best for whatever distance you decide to tackle!


Race day breakfast

  • Don’t try anything new for breakfast, it should be similar to what you’d eat the morning of a long run
  • Eat breakfast 2 hours before the race starts
  • Good ideas are: 1-2 wholemeal crumpets, or sourdough toast slices, or pancakes - spread with: raw honey or good quality jam + a handful of raw almonds on the side; or sliced banana and some raw nut butter
  • You can sip on 150ml of electrolyte drink or pure coconut water at breakfast too if you like


Pre-race snack

  • At 20 minutes before your start time have a small carbohydrate-loaded snack, giving your body the perfect amount of time to digest it before you hit the water, i.e.: 1 gel; 1-2 dates; half a banana; or 150ml of electrolyte drink that contains carbs
  • Apart from this snack, all you really need to do is sip on water after breakfast 


After the swim

  • As soon as you get out of the swim (no matter what distance), give your digestive tract a break for 15 minutes before consuming any carbs or electrolyte drinks.
  • You have just gone straight from swimming horizontally to running and then jumping on a bike, so the body is focused on pumping blood from your arms to your legs - there is no time to focus on digestion here! Give your body time to settle before fuelling, but feel free to sip on water in transition.


On the bike

  • In a sprint race - all you really need is a few sips of water & an electrolyte drink and 1 gel or date at the 3⁄4 mark of the bike leg
  • In an Olympic distance race - sip on water and an electrolyte drink throughout the bike leg and have 2 gels – one at the 20-minute mark, and one 10 minutes before you come into second transition
  • For half or full Ironman races - you want to be getting in approximately 25-30g of carbs and 1 or 2 salt stick tablets, every 30 -40 minutes and just stick to water on the bike (no electrolyte drinks - see why below)


Running – the home stretch

  • In a sprint race - fell free to sip on water or electrotype drinks at run aid stations if you’re thirsty, but you should have enough energy in the tank to make it to the finish line
  • In an Olympic distance race - hydrate at every (or every second) aid station with water, and at the 30-minute mark have a gel
  • For half or full Ironman races - hydrate with sips of water or electrolyte drinks at every aid station and refuel with gels every 45-60 minutes.


Electrolytes and carbs on long rides

There are carbs in your gels and electrolyte drinks, so on longer races it’s easy to overload your digestive tract, which results in race-day gastrointestinal issues. The best way to avoid this is to drink only water and not electrolyte drinks on the bike – the gels every 30 minutes give you enough carbs.

However you’ll be sweating a lot, so you must make sure you replace your electrolytes with appropriate salt stick tablets (these don’t have any carbs). 1 or 2 tablets taken with your gels every 30mins on the bike is perfect.

If you are seriously considering doing a half or full Ironman, I would highly recommend you get an individual race nutrition plan made up, that takes into account your gender, weight, carb needs, sweat rate and race goal time, to get the best out of your body. This is something I love to do, so feel free to contact me.


A note on gels

If you want to swap out your gels for something more like real food, try:

  • 2 dates(but don’t have too many, or the extra fibre might mean a toilet break mid-race)
  • Half a raw honey sandwich on white sourdough bread


Bec Stone

Clinical Nutritionist