Top tips for race day nutrition: fuel smarter
TL;DR:
- Good race day nutrition comes down to carb-loading, meal timing and drinking with electrolytes. Test your fuelling in training, keep new products away from race day and adjust for the conditions. A simple, consistent plan for food and fluids keeps your stomach settled and your energy up through long events.
Race day nutrition means planning your carbohydrate, fluids and meal timing so you keep your energy up and your stomach calm when you race. Every tip here comes back to one thing: what you eat and drink in the 36 hours before you start shapes your race more than anything you do on the day. Carbohydrate is your main fuel for endurance events. Electrolyte balance decides whether your muscles keep firing or start cramping. Get both right and you'll reach the start line with full glycogen stores, a settled stomach and a clear head.
1. What are the best carbohydrate loading strategies before race day?
Carb-loading means filling your glycogen stores in the 24-36 hours before a race. The target is 8-12g/kg of carbohydrate a day across that window. For a 70kg athlete that's 560-840g of carbs a day, which changes how your plate looks quite a bit.
Go for low-fibre, low-fat, familiar foods. White rice, pasta, bagels and bananas all fit. They digest quickly and turn into glycogen without the bloating or cramps that high-fibre foods can bring. Leave out wholegrain bread, lentils and cruciferous veg in this window. Your gut will thank you.
Timing matters as much as the food. Spread your carbs across three or four normal-sized meals instead of two huge ones. Eat your last main meal early in the evening, ideally by 7pm, so you've digested it before bed. A light carb snack before bed is fine if you're still short of your target.
- White rice or pasta with lean protein at lunch and dinner
- Bagels or white toast with jam or honey as snacks
- Bananas, rice cakes or sports drinks to top up between meals
- Skip high-fat sauces, creamy dressings and fried food completely
Pro Tip: Carb-loading keeps your total calories roughly the same. The idea is shifting macro composition so carbs take the place of fat and fibre. Overeating the night before a race just leaves you uncomfortable.
2. How should athletes fuel on race morning?
Your race morning meal sets your blood sugar and tops up liver glycogen after the overnight fast. Have 1-4g/kg of carbohydrate and finish eating 2-4 hours before your start. A 70kg runner aiming for 2g/kg needs about 140g of carbs: a large bagel with jam and a banana, plus a sports drink.
Keep fat and fibre low at this meal. Both slow gastric emptying, so food sits in your stomach longer and you're more likely to feel sick mid-race. A bit of protein is fine. The meal should feel light and familiar.
Good race morning options:
- Bagel with jam or honey and a banana
- Instant oats with sliced banana and a drizzle of honey
- White toast with a little peanut butter and a sports drink
- Rice cakes with jam and an electrolyte drink
Drink a moderate amount with your meal. Aim for 400-600ml of fluid with electrolytes in it, which tops up your sodium without overloading your stomach.
Pro Tip: Practise your pre-race breakfast before long training sessions at race pace. Your gut adapts to eating before hard efforts, and you want to find out in training if oats disagree with you.
3. What to eat before a race with an early start time
Very early starts are a real problem. A 6am start means a 3am alarm for a full meal, and most athletes can't face that. Instead, eat a normal dinner the night before, then have a small carb top-up 45-60 minutes before the start.
An energy gel, a banana or two rice cakes with honey all work in that window. They're fast-digesting carbs that lift your blood sugar and sit light in your gut. Keep the portion small. You're steadying your blood sugar, and a full breakfast would be too much.
Coaches recommend squeezing the breakfast window for early starts and leaning on these small top-ups to keep blood sugar steady early in the race. It works because the glycogen you stored from the previous evening's carb-loading is still largely there after a night's sleep.
4. What are the best strategies for nutrition and hydration during the race?
In-race fuelling is where plenty of athletes lose the time they gained in training. For events over 90 minutes, the evidence-based target is 60-90g of carbohydrate an hour. Athletes who under-fuel hit the wall. Those who hit their carb targets hold their pace.
Aim for 400-800ml of fluid an hour, more in heat or high humidity. Sodium should reach 300-1,000mg an hour to keep your electrolytes balanced and avoid exercise-associated hyponatraemia. Carbs, fluid and sodium are the three numbers every good race plan is built on.
Mix your carb sources for better absorption. Glucose-fructose blends, found in most good gels and sports drinks, use two separate transporters in your gut. That lets you absorb more carbohydrate an hour than glucose alone. Gels, chews and drinks that combine both sugars are the most efficient option for long events.
Go easy on plain water during the race. Too much plain water dilutes your blood sodium and causes hyponatraemia, which brings confusion, nausea and in severe cases seizures. Electrolyte drinks, or water with salty food, are much safer. Our article on hyponatraemia risks for athletes covers the physiology in detail.
Worth knowing: The 300-1,000mg an hour sodium range is wide on purpose. Sweat rate and sweat sodium vary a lot between athletes, so test your own needs in training.
Pro Tip: Start fuelling 15-30 minutes into the race, before you feel low. By the time you feel hungry or tired, your blood sugar has already dropped. Fuel early and you stay ahead.
5. Which nutrition mistakes should athletes avoid on race day?
The biggest mistake is trying a new gel, bar or drink on race day. Never introduce new nutrition products without testing them in training first. Stomach trouble mid-race is miserable, and it can force you to slow down or stop.
The second most common mistake is eating lots of fibre and fat in the 24 hours before. Both slow digestion and raise your chances of cramps and urgent toilet stops. Swap your usual wholegrain choices for white versions in this window.
Third is drinking too much plain water. Downing lots of water in the 45 minutes before the start leaves it sloshing in your stomach and dilutes your blood sodium. Small, frequent sips of an isotonic electrolyte drink work much better than gulping water at aid stations.
Timing mistakes cost athletes too. Eat within 60 minutes of the start and the insulin spike can cause reactive hypoglycaemia early in the race. Eat more than four hours before and your liver glycogen will be partly used up by the time you start. That's why the 2-4 hour window exists.
Nerves affect digestion directly. Adrenaline slows gastric emptying and can make you feel sick even with familiar food. Stick to your tested plan and resist eating extra because you're anxious.
6. How to tailor nutrition to different race lengths and start times
Race nutrition changes a lot with distance. A 5K runner needs a simple carb meal beforehand and almost nothing during. A marathon runner needs full carb-loading, a planned race morning meal and a detailed fuelling plan for the race. An ultra athlete needs all of that plus a plan for solid food and slower pacing so they can digest it.
| Race type | Carb-loading needed? | In-race fuelling | Fluid per hour |
|---|---|---|---|
| Short race (under 90 mins) | Minimal | Usually unnecessary | 400ml |
| Half marathon | Moderate | Optional from 60 mins | 400-600ml |
| Marathon | Full 24-36 hour protocol | 60-90g carbs/hr | 500-800ml |
| Half-Ironman or ultra | Full protocol plus solid food | 60-90g carbs/hr | 600-800ml |
Early starts squeeze your fuelling window. If you're racing at 6-7am, eat a carb-heavy dinner the night before, sleep, then take a small fast-digesting carb top-up 45-60 minutes before the start. Coaches working with endurance athletes recommend this because it saves you forcing down a big meal in the early hours.
Conditions change your targets too. Heat raises your sweat rate, so you need more fluid and more sodium. Adjust up from the baseline and test your hydration plan in similar conditions in training. Understanding electrolyte ratios before race day gives you a clear way to make those changes.
Key takeaways
Race day nutrition comes down to carb-loading, accurate meal timing and drinking with electrolytes matched to your losses, all tested in training first.
| Point | Details |
|---|---|
| Carb-load properly | Aim for 8-12g/kg of carbohydrate a day in the 24-36 hours before the race. |
| Time your race morning meal | Eat 1-4g/kg of carbohydrate 2-4 hours before the start. |
| Fuel early in the race | Start taking on 60-90g of carbohydrate an hour from 15-30 minutes in. |
| Pick electrolytes over plain water | Aim for 300-1,000mg of sodium an hour to prevent hyponatraemia and cramp. |
| Test everything in training | Every gel, drink and meal you race with should have a training trial behind it. |
What I have learned from watching athletes get this wrong
Athletes spend months building fitness and then throw it away in 36 hours with poor food choices. I've seen it again and again. The classic is the carb binge the night before, a huge plate of pasta swimming in cream sauce, then a restless night and a bloated start line. Their legs are ready, and their gut has had no practice.
Your gut needs training as much as your legs do. Use long sessions to try every product and timing you plan to race with. Athletes who practise their nutrition in training turn up with a gut that knows what's coming.
The other thing I see is overcomplicating it. Athletes read about glucose-fructose ratios and sodium transport and build a plan so complicated they can't follow it under pressure. The best plan is one you can stick to when you're tired, hot and 20 miles in. Keep it simple. Pick two or three products you know work, set a timer for your fuelling and stick to it.
Be patient as well. Gut adaptation takes weeks. If your first long run with gels goes badly, treat it as useful information. Change the product, the timing or the amount and try again. Athletes who treat nutrition as a skill to train improve much faster.
Tom
Interval's Starter Bundle: built for race day fuelling
The Interval Starter Bundle puts electrolytes and pre-workout in one order, so you can test both in training before you race.
Electrolyte+ gives you 1500mg of electrolytes per stick, and Pre-Shot is a 60ml shot with 200mg caffeine that's easy to time before your start. Both are made in the UK and allergen free, whether you're preparing for a marathon, a Hyrox or an ultra.
FAQ
What should I eat the night before a race?
A carb-heavy meal that's low in fat and fibre, like white pasta with a tomato sauce or white rice with chicken. Finish eating by 7pm so you've digested it before bed.
How many carbohydrates do I need during a marathon?
Aim for 60-90g of carbohydrate an hour from a mix of gels, chews and sports drinks with glucose-fructose blends so you absorb as much as possible.
What are the best pre-race snacks for early morning starts?
An energy gel, a banana or two rice cakes with honey 45-60 minutes before the start. They're fast-digesting carbs that steady your blood sugar and sit light in your stomach.
How do I avoid hyponatraemia during a race?
Swap plain water for electrolyte drinks and aim for 300-1,000mg of sodium an hour. Overconsumption of plain water without electrolytes dilutes your blood sodium and causes hyponatraemia.
When should I start fuelling during a race?
Start 15-30 minutes in, before you feel any drop in energy. Wait until you feel empty and your blood sugar has already fallen, and your pace will suffer.