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Hydration and endurance · Answer
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.
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.
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.
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 and best energy gels in South Africa.
Stomach cramps, nausea or bloating usually mean too high a concentration, too little water, or an untested product.
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 and carb loading for a marathon.
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.
| 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) |
Educational information, not medical advice. Speak to a doctor, pharmacist or registered dietitian before using supplements if you are pregnant or breastfeeding, under 18, taking medication, or living with kidney, liver or heart disease. Prices were observed in October 2026 and are not offers.