It seems to be a running joke among Ironman triathletes that “the fourth event” of Ironman races is eating. Mess up one of the four events, and you’re toast. In order to do a 140.6 mile race, you have to fuel up on the go. The best estimates conclude that triathletes burn around 10,000 calories during an Ironman (varies by gender, weight, age, etc.). Athletes burn off most of their body’s readily available energy stores (roughly 2000 calories in the form of glycogen) by the time they finish the 2.4 mile swim. That’s a problem when you still have 138 miles to go. Beyond making sure you eat properly and rest leading up to the event, it’s important to have a game-plan for constantly fueling up during the race. Everyone is different, so you need to figure out what food works best for you, but the following may be a good starting point.

You can’t really eat or drink during the swim. I ate my final meal about 2-3 hours before the race (or any big training sessions) and then sipped on water as needed. Right before we started, I ate a small granola bar to get something light in the system. Figure out what food digests easily and won’t result in any gastrointestinal distress while you are on the move.

While riding the bike, you can digest somewhere between 200 and 300 calories per hour.

Soon after exiting the water you want to start drinking and eating at a regular tempo and continue throughout the bike. I begun my nutritional plan in the transition from the swim to the bike, but others wait until they hop on the bike and hit the road before eating. Decide what works best for you. While riding the bike, you can digest somewhere between 200 and 300 calories per hour. I recommend trying a variety of energy bars and goo products in training to get a feel for what you like and how much you can handle while spinning the pedals on the bike. I would eat a CLIF bar every hour and a CLIF shotblock every 20 minutes when I wasn’t eating a CLIF bar. Feasting as much as you can on the bike is going to leave you with fuel in the tank when you hop off and start that marathon.

clif_shot_blocks_individualPhoto by Southbayriders

Eating on the run is similar to the bike, but scaled down. Your body can’t process as many calories while you run, so you’ll want to eat around 100 calories per hour. I chose to use 1 CLIF shotblock every 20 minutes for the run and a sip of gatorade every mile. Again, try eating during long runs in training and figure out what works best for you.

Get a big tub of Gatorade or Powerade mix.

My final overarching recommendation for your nutrition while training is to get a big tub of Gatorade or Powerade mix. For long rides and runs, you will be shocked to see how big a difference it makes to get some sugar and electrolytes into the bloodstream by sipping gatorade. Don’t believe me? Try a 50 mile ride with gatorade and a 50 mile ride without. The difference is only more dramatic the further you go.


If you nail the nutrition portion of your race plan, your body will have the energy you need to keep pushing mile after mile, and you won’t end up in one of the highlight reels on youtube of athletes collapsing 100 yards from the finish line. 

This is post 5 of 7 about my Ironman journey and pointers.