ironman nutrition plan

Ironman Nutrition Plan

The key to a successful Ironman completion involves balancing your race intensity and nutrition. The intensity will determine the rate at which calories are burned and the composition of the fuel used. 

In its simplest form – eat as much as you can while going as fast as you can 

The Ironman Nutrition Plan

Race week

During your taper when your training volume is reduced you will need fewer calories. Your aim is still to fuel well for your workouts even though they will be shorter. 

The day before your Ironman is usually when you see people smashing tonnes of carbs (carb loading). I would suggest maintaining your usual eating habits but increasing the carbs slightly in each meal and if possible eating your meals earlier in the day. Haribo sweets can be a good fuel source to fill up your liver glycogen stores. Yes, you read that right. 

Race morning

3-4am starts for most people which gives you time to eat and digest a good breakfast. Ideally, 2-3 hours before the start of your race. Overnight the glycogen in your liver would have depleted so it’s time to top them up with some carbs. Fructose carbs for the liver. Fructose carbs go into the liver first so that means the liver glycogen stores get replenished This meal should be tested prior to race day. 

Meal Idea: Porridge oats with some jam or honey. Simple but provides all your nutrition needs on race morning. 

Around 30 – 40 minutes before the start you can have an energy gel to top your levels up. 

The Swim 

You won’t be eating on this portion of the day. If you are a back-of-the-pack swimmer you could possibly store a gel in your wetsuit to consume during the Aussie exit but you should be fine from your breakfast and pre-race gel. 


This is a good opportunity to eat. However, don’t forget you are in a race so I would take your food onto the bike and get moving. 

The Bike 

This is the longest section and your best opportunity to take on some nutrition. Carbs are going to be your main source of fuel during an Ironman. Your body will take time to digest carbs and the longer you are out on the course the more difficult it will be to digest solids. I would suggest eating more solid foods earlier to give your body time to process it while it is still relatively fresh. 

Set yourself a schedule to regularly consume carbs. I would suggest between 50-90g of carbs per hour. That seems like a wide range but you need to be testing this prior to race day. maintaining consistent carb & calorie intake will help maintain steady performance and reduce the chance of dips in energy. Monitor your body, you should eat even when you don’t feel like it. Avoid taking on any more carbs about 20- 30 minutes before the end of the bike and just drink water. This will allow your body time to absorb and shouldn’t leave you feeling sick at the start of your run. 

My suggestion – A bottle with 15-18 gels and some energy blocks. Replace water at each aid station and take a caffeine tablet with around 45 minutes to go. 

The Run 

If you have fuelled correctly on the bike you should still have some glycogen remaining which will help as you start. Even while running at your preferred Ironman Pace it is going to be difficult to eat. The aim of the run is to consume as much as you can whilst maintaining your pace. Your intake will be much lower than the bike and I would probably avoid too much solid food at this late stage. 

Aid stations are usually frequent enough to use as your energy timings. A simple strategy would be to take on gels at each station. Don’t forget to test your intake in training and learn to understand what your body needs. 30 to 35 minutes out from the finish line you should stop eating anything. Your body won’t absorb it in time. The focus now should be to increase your pace and make it home! 

My suggestion – water at every station, energy drink at every other. Take on a gel every 30 – 45 minutes

Post Race

This is where most people would suggest eating everything and anything in sight. If you have fuelled correctly you shouldn’t feel like pigging out on everything you see. If you’ve been fancying something all day then by all means go nuts. However, if you are feeling sick or don’t fancy anything then I would suggest eating something small with some protein and some carbs in or even a recovery shake and then pick back up the larger meals the next day. This will allow your internals some time to recover from all the gels you’ve consumed during the race. 

Key Takeaways: 

  • Fuel well during race week

  • Have a solid fuelling strategy on race day but be prepared to be slightly flexible and listen to your body

  • Schedule your intake

  • Practice your race day nutrition