Fueling a distance runner

Walk into a gym or open Instagram and you’ll hear it: cut the rice, skip the roti, carbs make you fat. That might be fine if you sit at a desk all day. If you’re running 80–100 km a week in the hills of Uttarakhand, it’s terrible advice.

Here’s what the research actually says about carbs, and why runners need them.

Carbs are your running fuel

When you eat rice, roti, poha or a banana, your body turns the carbohydrate into glucose. What you don’t use straight away is stored in your muscles and liver as glycogen. Think of it as petrol in the tank. When you run hard, it’s the fuel your muscles reach for first.

Scientists showed this back in 1967. A Swedish team put athletes on low-carb, mixed and high-carb diets and timed how long they could keep exercising. On the high-carb diet, their muscles held far more glycogen and they lasted about three times longer than on the low-carb diet.¹

When the tank runs dry

You can only store so much glycogen, roughly enough for 90 minutes to two hours of hard running. When it’s gone, you slow down, your legs feel like concrete and your head goes foggy. Marathon runners call it hitting the wall.

Eating during long sessions helps. In one well-known study, trained athletes working hard on flavoured water gave up after about three hours. With a carbohydrate drink, they kept going for another hour.²

“But isn’t low-carb better?”

Keto and other low-carb, high-fat diets are popular, and some people say they turn athletes into fat-burning machines. In 2017, researchers at the Australian Institute of Sport tested this on world-class race walkers during three weeks of hard training.³

The keto group did burn a lot more fat. But they needed more oxygen to walk at race pace, which made them less efficient. By the end, the two high-carb groups were 5–7% faster over 10 km. The low-carb group hadn’t improved at all, even though they’d done the same training.

Same athletes, same training. Only the food was different, and only the ones eating carbs got faster.

How much do you need?

Sports nutrition experts work it out from your body weight and how much you train:⁴

Training load	Carbs per kg of body weight per day
Light / skill sessions	3–5 g
About 1 hour a day	5–7 g
1–3 hours a day	6–10 g
4–5+ hours a day	8–12 g

So a 50 kg runner training 1–3 hours a day needs about 300–500 g of carbs a day. To give you an idea, 300 g is roughly two cups of cooked rice, four rotis, three bananas and a plate of poha, plus the dal, milk and fruit you’d eat anyway.

Carbs from the Indian kitchen

You don’t need expensive gels or imported powders. Everyday Indian food has plenty of carbs.

• Before training (2–3 hours): poha, upma, idli with sambar, or roti with a little sabzi. Stick to food you know, and don’t make it too oily or spicy.
• During runs over 60–90 minutes: aim for 30–60 g of carbs an hour.⁴ A banana and a few dates will do it, or a bottle of nimbu-paani with sugar and a pinch of salt.
• After training: eat soon. In one study, athletes who had carbs straight after exercise refuelled their muscles about three times faster over the next two hours than when they waited.⁵ Curd rice, banana lassi, sattu sharbat or dal-chawal all work well.

For women athletes

A lot of young women athletes don’t eat enough, often without realising it. Some are trying to stay “light”. Others simply don’t have enough food. When your body is short of energy, it starts switching off things it can live without. Scientists call this REDs (Relative Energy Deficiency in Sport). It can stop your periods, weaken your bones and leave you injured or ill more often.⁶

Eating enough, and especially enough carbs, is one of the easiest ways to protect your health and your running. If your periods stop, that isn’t a sign you’re fit. Talk to your coach or a doctor.

References

1. Bergström J, Hermansen L, Hultman E, Saltin B. Diet, muscle glycogen and physical performance. Acta Physiologica Scandinavica. 1967;71(2):140–150. doi.org/10.1111/j.1748-1716.1967.tb03720.x
2. Coyle EF, Coggan AR, Hemmert MK, Ivy JL. Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. Journal of Applied Physiology. 1986;61(1):165–172. doi.org/10.1152/jappl.1986.61.1.165
3. Burke LM, Ross ML, Garvican-Lewis LA, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. Journal of Physiology. 2017;595(9):2785–2807. doi.org/10.1113/JP273230
4. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise. 2016;48(3):543–568. doi.org/10.1249/MSS.0000000000000852
5. Ivy JL, Katz AL, Cutler CL, Sherman WM, Coyle EF. Muscle glycogen synthesis after exercise: effect of time of carbohydrate ingestion. Journal of Applied Physiology. 1988;64(4):1480–1485. doi.org/10.1152/jappl.1988.64.4.1480
6. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine. 2023;57(17):1073–1097. doi.org/10.1136/bjsports-2023-106994

This article is general education, not personal medical advice. Athletes with specific health concerns should speak to a qualified sports dietitian or doctor.