7 best carbohydrate sources for endurance athletes

Picking the best carbohydrate sources for endurance comes down to two questions: how fast does it leave your stomach, and can you eat it with your heart rate at 170?

Most carb advice skips the second question. Porridge is a great breakfast and a terrible mid-race fuel. Both facts matter, at different times.

Jeukendrup's 2014 review in Sports Medicine sets the practical ceiling: roughly 60g per hour from a single carb source, rising to around 90g per hour when you combine glucose and fructose, because they use separate transporters in the gut. For exercise under about an hour, small amounts or even a carb mouth rinse can help.

Here are 7 sources worth building a plan around, ranked by how useful they are across a training week.

1. White rice

Low in fibre and fat, high glycaemic and almost everyone tolerates it. White rice is the go-to pre-race dinner for good reason: it gives you a big carb load minus the fibre that comes with brown rice, which is exactly what you want the night before a hard effort.

Typical serving: 200g cooked gives roughly 55g carbohydrate.

Use it: evening meals while carb loading, and 3-4 hours before a race.

2. Maltodextrin

A glucose polymer with a lower osmolality than the same amount of simple sugar, so it can carry more carbohydrate per unit of fluid with less effect on how fast your stomach empties. That's why it's the backbone of most sports drinks and gels.

It also tastes of very little, which makes it easy to get down in volume when nothing else appeals.

Typical serving: a 30g scoop gives roughly 28g carbohydrate.

Use it: during exercise over 60 minutes, and straight after a session.

3. Bananas

The most practical whole food carb on the list. A medium banana gives around 25g of carbohydrate, mostly as a mix of glucose and fructose, plus about 400mg of potassium.

Ripeness changes things. Green bananas have more resistant starch and sit heavier. Yellow with brown spots empties faster, and that's the one you want before training.

Typical serving: 1 medium banana, roughly 25g carbohydrate.

Use it: 60-90 minutes before a session, or during long steady work.

4. Glucose and fructose blends

This is why modern gels and drink mixes list two sugars. Glucose absorbs through the SGLT1 transporter and fructose through GLUT5. Use both and you raise the absorption ceiling from around 60g/h towards 90g/h, which can be the difference between fuelling a long session properly and running on fumes at the end of it.

Ratios in the research generally sit between 2:1 and 1:0.8 glucose to fructose. Anything in that range works for most people.

Typical serving: one gel, 22-30g carbohydrate.

Use it: any session over 90 minutes, and races where you need a high intake.

5. Oats

Oats are slower than everything else here, and that's the point. They release carbohydrate steadily thanks to their beta-glucan fibre, and they work well 3 or more hours before a session when you want steady blood sugar.

That fibre rules them out close to a race. Eat them inside 2 hours and you're gambling with your gut.

Typical serving: 60g dry oats gives roughly 40g carbohydrate.

Use it: breakfast on training days, 3-4 hours before hard efforts.

6. Potatoes

Underrated and cheap. Ultra runners have used boiled, salted potatoes for years, and the research backs them up.

In Salvador and colleagues' 2019 study in the Journal of Applied Physiology, 12 trained cyclists did a 120-minute ride followed by a time trial under three conditions. Potato and gel gave identical time trial performance (33.0 minutes each), both well ahead of water alone (39.5 minutes).

Salt them properly and they give you sodium too, which solves two problems at once. They're slower than a gel and a lot kinder on the palate after 3 hours of sweet stuff.

Typical serving: 200g boiled potato gives roughly 35g carbohydrate.

Use it: long steady sessions, and refuelling after training.

7. White bread with honey or jam

Unglamorous, and it's in every kitchen. Two slices of white bread with jam give you around 45g of carbohydrate with almost no fibre or fat, and they sit comfortably in most stomachs 90 minutes out.

It's what you reach for when you've run out of gels or patience, or you're travelling and the hotel breakfast is what it is.

Typical serving: 2 slices with jam, roughly 45g carbohydrate.

Use it: 1.5-2 hours before a session, or as an emergency stand-in for a sports product.

Matching the source to the session

A quick way to sort it:

• 3-4 hours out: oats, rice, potatoes. Volume and staying power.
• 60-90 minutes out: banana, white bread with jam. Low fibre and fast.
• During: maltodextrin, glucose and fructose blends. Nothing you have to chew.
• After: whatever gets 1.0-1.2g per kg of body weight into you in the first couple of hours.

For Hyrox, the race is short enough that most of the work happens beforehand. The 2025 Frontiers in Physiology study on recreational Hyrox athletes reported a mean finish of 86.5 minutes. That's right at the point where carbs during the race start to matter, and too short to rescue a poorly fuelled start. Front-load it, as covered in carb loading for Hyrox.

FAQ

How many grams of carbohydrate per hour should endurance athletes take during exercise?
Around 30-60g per hour for efforts of 1-2.5 hours from a single carb source, and up to about 90g per hour for longer events using a glucose and fructose blend. Build up gradually, because you can train your tolerance.

What is the best carbohydrate to eat before a race?
Something low in fibre that you've eaten before. White rice, white bread, a ripe banana or a plain bagel. The night before, go for volume. In the final 2 hours, go for whatever empties fastest.

Can you train your gut to absorb more carbohydrate?
Yes. Taking carbs regularly in training raises your gut's transporter capacity and reduces stomach symptoms over a few weeks. We covered the protocol in gut training for endurance athletes.

Are natural carbohydrate sources better than gels?
For absorption speed, gels and drinks win. They're designed to empty fast and they're easier to take at high intensity. Whole foods win on taste over long sessions and on cost. Most athletes end up using both.

Do you need carbohydrate for sessions under an hour?
Usually not for fuel, though a carb mouth rinse can improve performance in efforts of around 45-60 minutes. Starting with topped-up glycogen matters more than what you take during.

Fuel is one half of it. The other half is fluid and sodium, and Interval's Electrolyte+ covers that with 1500mg of electrolytes per stick, whichever carb source you settle on.