Swim, bike, run, with two transitions in between: triathlon is the endurance sport where nutrition plays out on the most fronts at once. The week before the race decides how full your stores are at the start, and the format changes everything: a sprint isn’t prepared like a 70.3 or an Ironman. Here’s the complete guide, from D-7 to the finish line.
In short: carb-loading depends on the format. None for a sprint, the day before for an Olympic distance, D-2 to D-1 or D-3 to D-1 for a 70.3 depending on your time, and three days for an Ironman, with 8 to 12 g of carbohydrate per kilo per day. Breakfast 2.5 to 3 hours before entering the water, then 60 to 90 g of carbohydrate per hour on the bike for the long formats.
Triathlon, a sport apart
Three sports means three digestive challenges. During the swim, you can’t eat. On the bike, the position and moderate intensity make it easy to fuel: that’s where it all happens. On the run, the jolting makes digestion harder. So the strategy is to start with full stores, load up on the bike and top up during the run.
Carb-loading: depending on your format
| Format | Typical time (amateur) | Carb-loading |
|---|---|---|
| Sprint | 1:15 to 1:30 | no loading: carbohydrate-rich dinner the night before |
| Olympic | 2 to 3 hours | the day before, or D-2 and D-1 if you’ll take more than 2:30 |
| 70.3 (half) | 4:30 to 6:30 | D-3, D-2 and D-1 (D-2 and D-1 if aiming for under 4 hours) |
| Ironman | 9 to 16 hours | D-3, D-2 and D-1 |
On loading days, aim for 8 to 12 g of carbohydrate per kilo per day, or 560 to 840 g for a 70 kg triathlete. That’s the level recommended for events longer than 90 minutes (Burke et al., 2011). The detailed protocol, with an example day, is in our guide Carb-loading: the complete protocol.
D-7 to D-4: keep things balanced
Training eases off, eating stays normal: starchy foods at every meal, a protein, vegetables, fruit. Don’t cut back too much thinking you’ll “lean up”: a deficit that week empties the stores you’re trying to fill and encourages muscle loss.
Loading days: pack in the carbohydrate
- carbohydrate becomes the base of every meal: pasta, rice, couscous, potatoes, white bread;
- add easy carbohydrate between meals: fruit purée, ripe banana, fruit juice, rice pudding, maltodextrin drink;
- cut back on fibre (pulses, raw vegetables, wholegrains) and fat (sauces, cheese, fried food);
- keep a moderate portion of protein at each meal;
- drink regularly: each gram of glycogen stored comes with about 3 g of water, and a gain of 1 to 2 kg is normal.
D-1: carbohydrate and a calm gut
The day before is often also race-pack pickup and bike check-in: plan your meals in advance so you don’t improvise. A generous, carbohydrate-rich lunch, a lighter dinner eaten early, at least 2.5 hours before bed. Nothing new, nothing spicy, no alcohol.
Race morning
- Breakfast 2.5 to 3 hours before entering the water, with about 1 to 2 g of carbohydrate per kilo: white bread or toast with honey or jam, a ripe banana, rice pudding or fine porridge oats, a hot drink. Get up early enough for it.
- Drink: 300 to 500 ml of water or diluted sports drink, in small sips.
- If there’s a long wait (more than 2 hours between breakfast and the start): a small sugary snack 30 to 40 minutes before, such as a banana or a gel with a little water.
During the race: the bike is your filling station
- Sprint: water, perhaps a gel or some sports drink on the bike.
- Olympic: 30 to 60 g of carbohydrate per hour, mostly on the bike.
- 70.3 and Ironman: 60 to 90 g of carbohydrate per hour, with glucose + fructose products above 60 g/h. Load up mainly on the bike (drink, gels, bars), then top up on the run with gels and drink at the aid stations.
Start fueling within the first 15 to 20 minutes on the bike, once your breathing has settled after the swim. Reaching 90 g/h takes a trained gut: see our 6-week gut-training plan.
Hydration across three disciplines
- Before the swim, drink normally, without overdoing it.
- On the bike, take a few sips every 10 to 15 minutes, or 400 to 800 ml per hour depending on the heat.
- In hot weather, choose a drink that contains sodium.
- On the run, drink small amounts at aid stations, without forcing it.
After the race: the first hours count
Within an hour of finishing, combine carbohydrate and protein (recovery drink, chocolate milk, sandwich), rehydrate with a drink containing sodium, then have a proper full meal within 2 to 3 hours.
The most common mistakes
- Carb-loading for a sprint triathlon.
- Eating too little during the taper for fear of gaining weight.
- Keeping pulses and raw vegetables the day before.
- Waiting until the run to start fueling.
- Trying a new product on race day, even if it’s handed out on the course.
Ograal builds your week for you
In Ograal, when you add your triathlon to the calendar as a race, with its duration and your start time, the app switches on carb-loading for the right number of days, adapts your meals, and calculates your breakfast and fueling based on your race duration. For details, see How our plans are calculated.
Create your free Ograal account
Frequently asked questions
Should I carb-load for a 70.3?
Yes. Most amateurs take more than 4:30: loading takes three days, from D-3 to D-1, at 8 to 12 g of carbohydrate per kilo per day.
What should I eat on triathlon morning?
A breakfast high in carbohydrate and low in fibre and fat, 2.5 to 3 hours before entering the water, then a small snack 30 to 40 minutes before if there’s a long wait.
How much carbohydrate per hour in an Ironman?
60 to 90 g per hour, mostly on the bike, and up to 90 g/h or more only if your gut has been trained for it.
Sources
- Burke, L. M., et al. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29(Suppl 1), S17-S27. DOI: 10.1080/02640414.2011.585473
- Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33. DOI: 10.1007/s40279-014-0148-z
- Thomas, D. T., Erdman, K. A., Burke, L. M. (2016). Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise, 48(3), 543-568. DOI: 10.1249/MSS.0000000000000852
