Nutrition needs grow as your runs get longer. Here's what matters at each stage.
5k and 10k
Your normal balanced diet is enough. Eat a light meal 2–3 hours before, or a small snack like a banana an hour before. Water is sufficient during the run.
Half marathon
- Increase carbohydrates on the day before and the morning of the race.
- For runs over about 75–90 minutes, taking some carbohydrate during the run (gels, chews or sports drink) can help.
- Practise your race-day breakfast on long training runs.
Marathon
- Carb loading: for 1–2 days before, eat around 8–10g of carbohydrate per kg of body weight with lower fibre and fat to avoid stomach issues.
- During: many runners aim for 30–60g of carbohydrate per hour; well-trained athletes may use more with practised gut training.
- Fluids and sodium: drink to thirst and include sodium; don't overdrink.
Recovery
After long runs, eat a meal with carbohydrates and 20–40g of protein within a couple of hours.
Golden rule
Nothing new on race day — test every gel, drink and breakfast in training first.
Runners who restrict food heavily risk low energy availability, which can affect hormones, bones and performance. Missed periods or frequent injuries warrant a GP visit.