How Many Carbs Per Hour Should Runners Take In?

Most runners know they should fuel during long runs, but very few actually hit the numbers. Instead, they wait until they feel hungry, tired, or sluggish to eat. By then, the body is already scraping the bottom of the glycogen tank. You wouldn’t head into a marathon with a quarter tank of gas in your car, but that’s exactly what happens when fueling falls short.

The science on carbs/hour

Decades of research in sports nutrition shows that endurance athletes can absorb 60–90 grams of carbohydrate per hour. The sweet spot depends on your gut tolerance, body size, and intensity.

• Below 60 g/hr, you’re almost guaranteed to run out of glycogen in longer events.

• Above 90 g/hr, absorption gets tricky unless you’re using a dual carb mix (glucose + fructose) that leverages multiple transporters in the gut.

This isn’t just theory. Elite marathoners, ultrarunners, and Ironman athletes consistently target high carb intakes to keep fueling steady. The difference between 40 g/hr and 90 g/hr over a 10-hour ultra can mean thousands of calories. That’s the gap between finishing strong and shuffling through the last 20 miles.

Training your gut matters

The gut is like a muscle — it adapts. If you’re not used to taking in carbs while running, 90 g/hr will wreck you. That’s why you start small. Begin with 30–40 g/hr in training runs. Slowly build toward 60–70, then test higher intakes. By race day, your stomach will be ready.

This is where a high-carb drink mix shines. Instead of choking down 8 gels, you sip from your bottle. Dirtbag Hydration delivers a heavy carb payload in liquid form, making it easier on the stomach and simpler to keep fueling consistent.

Sodium: the underrated piece

Carbs are the main show, but sodium keeps your system running. Without it, fluids don’t absorb well, muscles misfire, and cramping risk spikes. Dirtbag Hydration delivers 400 mg sodium per serving, a baseline that works two ways:

• Light sweaters get enough sodium to cover losses without kidney overload.

• Heavy sweaters can top up with extra salt tabs or capsules to match their needs.

This flexibility is key. Most runners don’t know their exact sweat sodium concentration, and it can vary from 400 mg/L to over 1500 mg/L. Starting with a smart baseline lets you adapt instead of guessing.

Practical example

Let’s say you’re training for a 50K. You plan to run 6 hours at moderate intensity. That’s 60–80 g carbs per hour, or roughly 360–480 g carbs total. With Dirtbag Hydration, that’s about 6–8 servings across the day. Add water alongside, and maybe a few real food snacks, and you’ve got a sustainable fueling plan.

Bottom line

Most runners underfuel because they underestimate their carb needs. Start with 60 g/hr, train your gut to handle more, and pair it with a steady sodium baseline. Dirtbag Hydration makes this simple: high carbs in every sip, sodium that covers most athletes, and flexibility for those who need more. That’s how you go from surviving your long runs to actually finishing strong.