A 45-minute run, a 3-hour hike, cycling all day: when and what should you eat?
In brief
- Less than 1 hour: water, according to thirst, is enough.
- 1 to 2 hours: aim for 30 to 60 g of carbohydrates per hour, starting within the first 45 to 60 minutes.
- More than 2 h 30: up to 90 g of carbohydrates per hour, with a mix of sources (glucose and fructose) and a trained gut.
- Beyond 2 to 3 hours while sweating heavily: replace sodium as well.
- Always test your strategy during training, never for the first time on race day.
General rule…
What we gain from drinking or eating during exercise depends on its duration and intensity. Here’s the summary, followed by an explanation:
| Exercise duration | Drink? | Eat? |
|---|---|---|
| Less than 1 hour | Water, listening to your thirst | No need for anything |
| 1 to 2 hours | Water or a sports drink, listening to your thirst | Yes, 30 to 60 g of carbohydrates per hour |
| More than 2 hours | Water or a sports drink with electrolytes, listening to your thirst | Yes, 30 to 90 g of carbohydrates per hour, plus a little protein as needed for satiety |
Less than 1 hour
We don’t need anything special, other than water. Our thirst will dictate how much we need. Our needs increase when it’s hot, when we sweat heavily, or when we’re working really hard.
If we train fasted in the morning, that’s the exception. It’s better to carry a snack in case you need it, and eat it before you see stars!
1 to 2 hours
Sports drinks, homemade or store-bought, are convenient for providing both water and carbohydrates (sugars). You can also drink water and eat snacks (squares, balls, etc.).
Whatever you choose, start fueling within the first 45 to 60 minutes of training to avoid a drop in energy and performance. Above all, don’t wait until you feel weak, because it will be difficult to recover. Continue drinking or eating every 20 to 30 minutes, aiming for 30 to 60 g of carbohydrates per hour. This is at least the equivalent of one 500 ml bottle of sports drink, 5 dried dates, 45 ml of maple syrup or 2 balls or 1 Zenit square.
More than 2 hours
Start drinking or eating within the first hour, still aiming for 30 to 60 g of carbohydrates per hour. For an ultramarathon, a long cycling event, or another effort lasting more than 2 h 30, needs can rise to as much as 90 g of carbohydrates per hour. At these amounts, combine glucose and fructose sources (dried fruit, maple syrup, suitable drinks and gels) to absorb them more effectively, and gradually train your gut during workouts. Eating becomes a sport in itself!
It becomes especially important to have a variety of foods available so you don’t get tired of them: sweet foods, salty foods (crackers, pita bread, vegetable juice, etc.), maltodextrin-based drinks (less sweet-tasting, but just as effective), and above all, foods you feel like eating, because eating can make all the difference between continuing and hitting the wall.
For long events, you can also eat foods that contain a little protein and fat, because they are more filling and help keep hunger at bay. A handful of nuts and seeds, cheese, jerky, or snacks made with peanut butter, nut butter, or plant-based proteins can be useful. Zenit energy squares are made with these ingredients.
If you sweat heavily for 3, 4, 5 hours or more, it’s essential to replace the electrolytes you lose, especially sodium. Store-bought sports drinks contain them. You can also add them to homemade drinks by including ¼ tsp of salt per litre, or use electrolyte powder.
1, 2, test
When you’re taking part in a long event that you’ve prepared for over several months, you want to give yourself the best possible chance of success. To avoid digestive surprises, it’s better to try your nutrition strategy during training. An emergency in the bushes is never fun.
Frequently asked questions
How many carbohydrates per hour during a race?
For an effort lasting 1 to 2 hours, aim for 30 to 60 g of carbohydrates per hour. For an effort lasting more than 2 h 30, needs can rise to as much as 90 g per hour, combining glucose and fructose.
When should you start eating during exercise?
Within the first 45 to 60 minutes, then every 20 to 30 minutes. Don’t wait until you feel weak.
Do you need to eat during a workout lasting less than an hour?
No. Water according to your thirst is enough, unless you’re training fasted: in that case, carry a snack with you.
How many Zenit balls or squares should you have during exercise?
About 2 balls or 1 Zenit square provide approximately 30 g of carbohydrates, which is the minimum target per hour for an effort lasting 1 to 2 hours.
By Stéphanie Côté, M.Sc., nutritionist
Speaker and author of “Knowing What to Eat – Sports Nutrition,” published by Modus Vivendi, 2019
Reviewed and updated in October 2026 by Danielle Dubois, nutritionist.
References
- Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016;48(3):543-568. PMID: 26891166
- Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44(Suppl 1):S25-S33. PMID: 24791914
- American College of Sports Medicine; Sawka MN, Burke LM, Eichner ER, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390. PMID: 17277604