Race-Day Fueling: The Plan, Not the Improvisation
Race day is the day you repeat what already worked. The plan you fuel with is the one you rehearsed for weeks, written down, with the rate, the products, the timing and the breakfast all familiar. This guide runs in the order you live it: weeks out, race week and race morning, then the race. The amounts are a starting point for a typical runner, and your own long runs revise them. This is general training guidance.
Weeks out, rehearse the plan
Practice near your race-day carbohydrate rate on your long runs for four to six weeks, with the products and the clock you will race with. The stomach adapts slowly, so one or two gels on one long run is not a rehearsal. See the guides on training your gut and carbohydrate during exercise for the climb and the amounts.
Eat the race breakfast before those long runs, at the time the race will start. A 4 a.m. start and a 10 a.m. start ask different things of the gut, and it needs to be ready for yours.
Nothing is new on race day, and that includes the rate. Drinking 500 milliliters an hour in training and a liter in the race is new, and so is 40 grams of carbohydrate in a three-hour run followed by 50 or 60 grams an hour in the race.
Write the plan down instead of carrying it in your head: the grams an hour, the products, the time or mile marker of each feed, the drink plan and the breakfast. Write up what happened once you finish. A rate that felt fine in one build can turn on you in the next, and the last one on paper is how you know.
Race week and race morning
Eat familiar food all week. For a race that takes longer than about 90 minutes, shift the last day or two toward carbohydrate (see carb loading). For a shorter race, eat normally.
On race morning, eat the breakfast you have eaten before long runs. A 2004 review found that carbohydrate 3 to 4 hours before exercise raises liver and muscle glycogen and improves later endurance performance1. Keep it low in fiber and light on fat. In a survey of 805 recreational long-distance runners in China, foods high in fat, protein, fiber or fermentable carbohydrate were commonly linked with stomach distress, and eating within 30 minutes of the start went with more bloating and an urge to defecate2. That is an association and not proof, so test it on your own long runs.
Carbohydrate in the last hour before a start can make some runners feel shaky, like low blood sugar. A 2004 review found no convincing evidence that it makes performance worse and says individual experience should decide1. Take a gel or a few sips of sports drink in the last half hour only if that has gone well in training.
For a short race, do not run fasted. For a morning 5K, take a banana on waking. For a 7 p.m. 5K, eat an ordinary breakfast and lunch, a lighter lower-fat meal at 3 and a banana at 5. If you use caffeine, it belongs in the plan and in your long runs too.
During the race
Under 90 minutes you need nothing in the race. A half marathon that takes you longer than 90 minutes is past that line, so use the plan below.
Past 90 minutes, take the first gel before you feel empty, at 60 to 75 minutes, and one about every 30 minutes after that, or every 35 to 40 if your stomach is touchy. Take it by the clock, in small amounts at regular intervals, and not by feel. The rate and the products are the ones you rehearsed.
Expect to miss a feed. Take the next one on schedule and at the usual amount, because a double dose is more carbohydrate at once than your stomach has practiced.
Know where the aid stations are, so you can plan when to take fluid and fuel around them, and practice drinking on the move in training. Drink to the plan you rehearsed, set from your sweat rate and tuned by feel, and treat weight gained across the race as the warning sign of overdrinking. On a hot day, run by effort and start more conservatively. See the guides on hydration and electrolytes and race-day pacing.
Safety
Do not try a new product, a new drink or a large jump in carbohydrate on race day.
Severe or lasting stomach pain, repeated vomiting or blood in your stool are reasons to stop and get medical help. So are confusion, headache or nausea with bloating after drinking a lot of fluid.
Common questions
What should I eat on the morning of a race?
The breakfast you have eaten before your long runs, eaten at the time the race will start, low in fiber and light on fat. For a short morning race, do not run fasted: take a banana on waking.
When should I take my first gel?
In a race longer than 90 minutes, at 60 to 75 minutes, before you feel empty, and then about every 30 minutes. Under 90 minutes you need nothing in the race.
Can I try a new gel on race day?
No. Nothing is new on race day, including the rate. Rehearse the products and the clock on your long runs for four to six weeks.
What if I miss a feed?
Take the next one on schedule and at the usual amount. A double dose is more carbohydrate at once than your stomach has practiced.
Should I take a gel right before the start?
Only if that has gone well in training. Eating within 30 minutes of the start went with more bloating in a survey of recreational runners, and carbohydrate in the last hour can make some runners feel shaky without making performance worse.
Sources
- Hargreaves M, Hawley JA, Jeukendrup A. Pre-exercise carbohydrate and fat ingestion: effects on metabolism and performance. Journal of Sports Sciences 22(1):31-38 (2004). (Review of pre-exercise carbohydrate and fat ingestion) ↩
- Zhao X, Chen Y, Li X, Wen W, Zhang J, Qiu J. Gastrointestinal symptoms among recreational long distance runners in China: prevalence, severity, and contributing factors. Frontiers in Nutrition 12:1589344 (2025). (Online and offline questionnaire, 805 valid responses from recreational long-distance runners in China, January to December 2024) ↩
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