Why fueling makes a difference
Carbohydrate is the main fuel for hard and long exercise, and your body only stores a limited amount. What you eat in the hours before a session, and what you take during it, decides how much is available when the effort gets hard. For short or easy sessions, your usual meals are often enough. For long sessions, hard intervals and competition, a plan makes a real difference.
The right plan depends on your sport, the length and intensity of the session, the time of day and, above all, your gut. Foods and amounts that suit one athlete upset another, and the gut can be trained to tolerate more fuel. That is why race-day fueling should be rehearsed in training, not improvised on the day.
Before: what to eat, and when
Current guidance suggests about 1 to 4 g of carbohydrate per kg of body weight in the 1 to 4 hours before a long or hard session. The closer to the start, the smaller and simpler the food.
- 3 to 4 hours before
A full meal
Built around carbohydrate, with some protein, and moderate in fat and fibre.
- Oatmeal with banana and milk
- Bagel with peanut butter and jam
- Rice or pasta with chicken
- 1 to 2 hours before
A lighter meal or large snack
Mostly carbohydrate, and lower in fat and fibre.
- Toast with jam
- Yogurt with fruit
- A fruit smoothie
- 30 to 60 minutes before
A small top-up, if you want one
Easy to digest. Useful for early starts, when a full meal is not realistic.
- A banana
- An applesauce pouch
- A few crackers
- Sports drink
During: how much carbohydrate per hour
How much you need depends mostly on how long the session lasts. These are the ranges sports nutrition research supports, as starting points to practise.
Per hour, up to
60 g
- Over 2 h 30 min
- 150 g
- Every 20 minutes
- 20 g
For example: 500 mL of sports drink and 1 gel per hour
Starting points, not a prescription. Build up gradually in training, especially above 60 g per hour.
| Session length | Carbohydrate | For example |
|---|---|---|
| Under 45 min | Not needed | Water |
| 45 to 75 min | Small amounts or a mouth rinse | A few sips of sports drink |
| 75 min to 2 h | Up to 30 g per hour | About 500 mL of sports drink per hour |
| 2 to 2.5 h | Up to 60 g per hour | 500 mL of sports drink and 1 gel per hour |
| More than 2.5 h | Up to 90 g per hour | Products that combine glucose and fructose, such as 500 mL of drink and 2 gels per hour |
Compare all session lengths
Carbohydrate during exercise, by session length
- Under 45 min
- Not neededWater
- 45 to 75 min
- Small amounts or a mouth rinseA few sips of sports drink
- 75 min to 2 h
- Up to 30 g per hourAbout 500 mL of sports drink per hour
- 2 to 2.5 hYour session
- Up to 60 g per hour500 mL of sports drink and 1 gel per hour
- More than 2.5 h
- Up to 90 g per hourProducts that combine glucose and fructose, such as 500 mL of drink and 2 gels per hour
What 30 g of carbohydrate looks like
Handy for turning grams per hour into food you can carry. Values are approximate, so check labels for exact amounts.
- 30 g500 mL of sports drink (6%)
- 27 g1 medium banana
- 20 to 30 g1 energy gel
- 36 g2 Medjool dates
- 30 g1 slice of bread with 1 tbsp of honey
- 32 g40 g of pretzels
Race week and race day
The day before
Eat familiar, carbohydrate-rich meals. If your stomach is sensitive, go a little lower in fibre. The night before a race is not the time to try a new restaurant.
Carbohydrate loading
For events lasting more than about 90 minutes, eating more carbohydrate (around 10 to 12 g per kg of body weight per day) for 36 to 48 hours beforehand can increase stored fuel. Shorter events do not need it.
Train your gut
Practising your fueling in long sessions, and building up the amount gradually, can increase how much carbohydrate you tolerate and reduce stomach problems.
Nothing new on race day
Test every food, drink and timing in sessions that resemble the event, including early starts and race intensity.
WORKING WITH YOUR DIETITIAN
How we work on it together
Map your sessions and events
We look at your training week, event distances, start times and what has gone well or badly before, including stomach problems.
Write the plan
You leave with what to eat the day before, the morning of and during the event, with amounts per hour translated into foods and products you actually like.
Rehearse and refine
You test the plan in your long sessions. At follow-up, we adjust amounts, timing and products based on how it felt.
Common questions
How long before training should I eat?
A larger meal works best 3 to 4 hours before. A small, easy-to-digest snack can work 30 to 60 minutes before. Individual tolerance matters most, so it is worth testing a few options.
Can I use real food instead of gels?
Yes. Bananas, dates, rice cakes and similar foods work well, especially at lower intensity. Gels, chews and drinks are easier to carry and digest at race pace. Many athletes mix both.
I get stomach problems when I eat during races. What can I do?
Common causes include too much fibre, fat or concentrated sugar, dehydration, and products you have not practised with. Building up fueling gradually in training often improves tolerance. Persistent symptoms deserve a review with your dietitian and, if needed, your doctor.
My race is in a few weeks. Is that enough time?
Yes. A few weeks is enough to build a plan and rehearse it in your long sessions. The earlier you start practising, the more room there is to adjust.
Based on current sports nutrition guidelines
- Thomas, Erdman & Burke (2016). Nutrition and Athletic Performance. ACSM, Academy of Nutrition and Dietetics & Dietitians of Canada joint position statement.
- Jeukendrup (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine.
- Kerksick et al. (2017). ISSN position stand: nutrient timing.
This page is general information, not individual advice. Your needs depend on your sport, health and goals.
Get a plan built for your sport.
Start with a free initial consultation, in person in Ottawa or Gatineau, or online anywhere in Ontario and Quebec.