7 best carbohydrate sources for endurance athletes

Picking the best carbohydrate sources for endurance athletes comes down to two questions: how fast does it empty from your stomach, and can you eat it while your heart rate is at 170.

Most carb advice ignores the second question entirely. Porridge is a fine breakfast and a terrible mid race fuel. Both facts matter, and they matter at different times.

Jeukendrup's 2014 review in Sports Medicine sets the practical ceiling: roughly 60g per hour from a single carbohydrate source, rising to around 90g per hour when you combine glucose and fructose, because they use separate intestinal transporters. Below about an hour of exercise, small amounts or even a carbohydrate 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 fibre, low fat, high glycaemic index, and almost universally tolerated. White rice is the default pre-race dinner for a reason: it delivers a large carbohydrate load without the fibre that brown rice brings, which is exactly what you want the night before a hard effort.

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

Use it: evening meals during a loading phase, and 3 to 4 hours pre-race.

2. Maltodextrin

A glucose polymer with a lower osmolality than an equivalent amount of simple sugar, which means it can carry more carbohydrate per unit of fluid without slowing gastric emptying as much. It's the backbone of most sports drinks and gels for that reason.

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

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

Use it: during exercise over 60 minutes, and in the immediate post-session window.

3. Bananas

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

Ripeness changes the picture. Green bananas hold more resistant starch and sit heavier. Yellow with brown spots empties faster and is the version you want before training.

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

Use it: 60 to 90 minutes pre-session, or during long steady work.

4. Glucose and fructose blends

The reason modern gels and drink mixes list two sugar sources. Glucose absorbs through the SGLT1 transporter, fructose through GLUT5. Use both and you raise the absorption ceiling from around 60g/h toward 90g/h, which is the difference between fuelling a long session 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 band works for most people.

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

Use it: any session over 90 minutes, and races where intake needs to be high.

5. Oats

Slower than the rest of this list, which is the point. Oats deliver a sustained carbohydrate release with beta-glucan fibre, and they work well 3 or more hours before a session when you want steady blood glucose rather than a spike.

The fibre content rules them out close to a race. Anything 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 to 4 hours before hard efforts.

6. Potatoes

Underrated and cheap. Boiled and salted potatoes have been used in ultra endurance for years, and the evidence backs the practice.

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

They also carry sodium if you salt them properly, which solves two problems at once. Slower than a gel, and a lot easier on the palate after 3 hours of sweet things.

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

Use it: long steady sessions, and post-session refuelling.

7. White bread with honey or jam

Unglamorous, and available in every kitchen. Two slices of white bread with jam gets you around 45g of carbohydrate with almost no fibre or fat, and it sits comfortably in most stomachs 90 minutes out.

It's the option to reach for when you've run out of gels, run out of 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 to 2 hours pre-session, or as an emergency substitute for a sports product.

Matching the source to the session

A quick way to sort it:

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

For a Hyrox specifically, 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, which sits right at the point where in-race carbohydrate starts to matter without being long enough to fix a poor 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 to 60g per hour for efforts of 1 to 2.5 hours from a single carbohydrate source, and up to about 90g per hour for longer events when using a glucose and fructose blend. Build up gradually, because tolerance is trainable.

What is the best carbohydrate to eat before a race?
Low fibre and familiar. White rice, white bread, a ripe banana or a plain bagel. The night before, go for volume. In the final 2 hours, go for speed of emptying.

Can you train your gut to absorb more carbohydrate?
Yes. Repeated exposure to carbohydrate during training raises intestinal transporter capacity and reduces gastrointestinal symptoms over a few weeks. We covered the protocol in gut training for endurance athletes.

Are natural carbohydrate sources better than gels?
For absorption rate, no. Gels and drinks are engineered to empty fast and are easier to consume at high intensity. Whole foods win on palatability over long durations and on cost. Most athletes end up using both.

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

Fuel is one half of the equation. The other is fluid and sodium, and Interval's Electrolyte+ handles that side alongside whichever carbohydrate source you land on.