# How many carbs per hour do you need for a marathon or ultra?

Source: https://www.healthnews24.co.za/answers/how-many-carbs-per-hour-for-marathon-and-ultra/
Publisher: Healthnews24 (South Africa's supplement answer desk)
Updated: 2026-10-27

> For a marathon or ultra, aim for up to 60 g of carbohydrate an hour from about two to three hours, and up to 90 g an hour beyond 2.5 hours using a glucose-plus-fructose blend at roughly 2:1. Below about two hours, 30 g an hour is usually enough. Train your gut in advance. People with diabetes need an individual plan.

Key facts:
- Jeukendrup (2014): up to 30 g/h for 1–2 h, up to 60 g/h for 2–3 h, and up to 90 g/h beyond 2.5 h with glucose plus fructose.
- Glucose-only absorption tops out at about 60 g of carbohydrate an hour.
- At 60 g an hour, Biogen Elite Carb Gel costs about R60 an hour and Maurten Gel 100 about R163–R180 (October 2026 prices).
- Train your gut in advance: build intake by about 10 g an hour every week or two using race products.
- Take small amounts every 15–20 minutes rather than large boluses.

## How many carbs per hour do you need for a marathon or ultra?

The Jeukendrup (2014) framework is the standard starting point:

| Event duration | Carbohydrate per hour |
|---|---|
| Under 30 minutes | none needed |
| 30–75 minutes | small amounts or a mouth rinse |
| 1–2 hours | up to 30 g |
| 2–3 hours | up to 60 g |
| Over 2.5 hours | up to 90 g, using glucose plus fructose |

Most recreational marathoners taking 3.5–5 hours should work towards **60 g an hour**, and ultra runners may build to **60–90 g an hour**. Some elite athletes train their guts to handle more, but that is not a starting target.

## Why do glucose and fructose matter?

The gut absorbs glucose through one transporter that saturates at about 60 g an hour. Fructose uses a different transporter, so a glucose-plus-fructose blend (around 2:1, or closer to 1:0.8 at the highest intakes) lets you absorb more. Single-source products may limit you. Check labels: Maurten Gel 100 lists a fructose:glucose ratio of about 0.8:1, Biogen Elite Carb Gel lists maltodextrin and fructose, and the 32Gi High Intensity Gel lists brown rice syrup with no fructose in the ingredients we saw.

## How does that translate to gels and drinks?

October 2026, using published carbohydrate amounts (our calculation):

| Per hour | Biogen Elite Carb Gel (45 g, R44.99) | Maurten Gel 100 (25 g, R75; box R68) | 32Gi Race drink (68 g per 75 g serving, R39) |
|---|---|---|---|
| 30 g | 0.7 gel, about R30 | 1.2 gels, about R90 | 0.44 serving, about R17 |
| 60 g | 1.3 gels, about R60 | 2.4 gels, R163–R180 | 0.9 serving, about R35 |
| 90 g | 2 gels, about R90 | 3.6 gels, R245–R270 | 1.3 servings, about R52 |

Over a 10-hour Comrades at 60 g an hour, that is roughly R600 on Biogen Elite versus about R1 600–R1 800 on Maurten gels, so mixing drink, gels and food is common. Compare prices in [cheapest energy gel per 30 g of carbohydrate](/answers/cheapest-energy-gel-per-30g-carbs-south-africa/) and [best energy gels in South Africa](/answers/best-energy-gels-in-south-africa/).

## How do you train your gut?

1. Start with 30–40 g an hour in long training runs.
2. Add 10 g an hour every week or two, using the exact products you will race with.
3. Take small amounts every 15–20 minutes rather than large boluses.
4. Practise with the fluid volume you will drink in the race.

Stomach cramps, nausea or bloating usually mean too high a concentration, too little water, or an untested product.

## What about fluid and sodium?

Carbohydrate and fluid are separate decisions. Drink to thirst, because overdrinking raises hyponatraemia risk, especially in events over four hours. See [how much sodium per hour in South African heat](/answers/how-much-sodium-per-hour-running-in-south-african-heat/) and [carb loading for a marathon](/answers/carb-loading-for-a-marathon-how-to/).

## Who should adjust the numbers?

- **Slower runners** in very long events need fewer grams per hour but for more hours.
- **Diabetes:** needs an individual plan with a clinician.
- **Fructose malabsorption:** avoid fructose-heavy products and take advice.
- **Short races:** a 10 km needs no gels.

## When should you see a professional?

A registered sports dietitian can build a race-day plan around your pace, sweat rate and gut tolerance. See a doctor if you have diabetes or persistent gut symptoms. This is general information, not personal medical advice.

Under-18s should fuel with normal food and drinks, and pregnant athletes, people with kidney disease and anyone on regular medication should get individual advice.

## Products mentioned

| Product | Size | Price (source, date) | Servings | R per serving | Sweeteners |
|---|---|---|---|---|---|
| Biogen Elite Carb Energy Gel, unflavoured (60 g) | 60 g sachet | R44.99 (Dis-Chem Living Fit, 2026-10) | 1 | R44.99 | None listed |
| Maurten Gel 100 (40 g sachet) | 40 g sachet | R74–R75 (goneoutdoor / The Athlete's Foot via PriceCheck, 2026-10) | 1 | R75.00 | None listed |
| 32Gi Race High Intensity Sports Drink (900 g) | 900 g | R470 (Dis-Chem Living Fit, 2026-10) | 12 | R39.17 | None listed |
| 32Gi High Intensity Sports Gel (27 g) | 27 g sachet | R25–R35 (Dis-Chem (energy and endurance), 2026-10) | 1 | R34.99 | None listed (rice syrup, flavouring, salt, preservatives) |

## Sources

- [Jeukendrup 2014, A step towards personalized sports nutrition: carbohydrate intake during exercise (Sports Med)](https://pmc.ncbi.nlm.nih.gov/articles/PMC4008807/)
- [Thomas, Erdman & Burke 2016, Position of the Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM: Nutrition and Athletic Performance](https://pubmed.ncbi.nlm.nih.gov/26917108/)
- [Dis-Chem: Energy and endurance](https://www.dischem.co.za/fitness/energy-and-endurance)