This guide follows widely used sports-nutrition guidance, including the 2016 joint position stand on nutrition and athletic performance from the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada. It’s general guidance for healthy adults, not medical advice.
The day before
For events longer than about 90 minutes, eating more carbohydrate in the 36 to 48 hours beforehand fills your glycogen stores. The position stand gives 10 to 12 grams per kilogram of body weight per day for this. In practice: carb-rich meals and snacks, a little less fibre and fat, and nothing new or unfamiliar.
Race breakfast
One to four hours before the start, a carbohydrate-rich breakfast tops up your stores. The guidance range is 1 to 4 grams per kilogram, with less the closer you are to the start. Choose foods you’ve eaten before long training sessions.
During the race
| Duration | Carbs per hour |
|---|---|
| Under 1 hour | Not needed |
| 1 to 2.5 hours | 30 to 60 g |
| Over 2.5 hours | 60 g, up to 90 g with a trained gut |
Above about 60 grams per hour, products that combine glucose and fructose are absorbed better than glucose alone. Start early, eat little and often, and set a timer: every 20 minutes works well. The fueling calculator turns this into bottles and gels for your race.
Fluid and sodium
How much you need to drink depends on heat, intensity and how much you sweat. Many athletes land between 400 and 800 ml per hour. Drinking to thirst is a sensible guide; drinking far more than you sweat out is risky. In long or hot races, adding sodium through sports drinks or electrolytes helps many athletes, especially heavy or salty sweaters.
Train your gut
- Practise race fueling on every long session, with the exact products you’ll use.
- Build your carbs per hour up over several weeks.
- Note what works and what doesn’t. A plan you’ve tested beats a perfect plan you haven’t.
Triathlon specifics
You can’t eat while swimming and it’s harder while running, so the bike is where most fueling happens. Keep fueling steadily through the last part of the bike; on the run, gels, sports drink and what’s at the aid stations keep you going.
When to ask a professional
If you have diabetes, a heart, kidney or blood pressure condition, or a history of stomach problems in races, talk to a doctor or registered sports dietitian before changing how you fuel.
