Long Run Fueling Guide: Carbs Per Hour That Actually Stick
Easy long runs feel fine unfueled — until they become marathon dress rehearsals. The conflict is “I felt okay at 90 minutes without gels” versus the late-race fade that starts when glycogen and gut practice were never stacked. Fueling is a skill you train, not a medal-day accessory.
Carb Targets Per Hour
Common sports-nutrition starting ranges for runs ~90+ minutes: ~30–60 g carbohydrate/hour, with some experienced runners practicing toward ~60–90 g/hour using multiple carb sources. Begin at the low end if you are new to gels. Easy pace still needs fuel on long efforts — use the Pace Calculator for intended long-run pace, and treat calorie estimates from the Calories Calculator as rough energy context, not a gel prescription.
Worked Scenario: 2.5-Hour Long Run at ~60 g/hour
Target ~150 g total carbs during the run (plus a normal pre-run meal). Example schedule you can adjust:
- 0:20: first gel (~20–25 g) or sip sports drink
- 0:50 / 1:20 / 1:50: repeat ~20–25 g
- Fluids: small, frequent sips; include sodium if you are a salty sweater or running in heat
If 60 g/hour wrecks your gut, drop to 30–40 g/hour for two weeks, then add 5–10 g/hour. Race day copies the successful long-run pattern — see race-day nutrition.
Train the Gut on Purpose
Practice the same products, flavors, and timing you will race. Alternate brands mid-block only if you are deliberately testing backups. Pair fueling with realistic effort: some long runs should include race-pace segments so the gut learns under load, not only on conversational jogs.
Per-hour targets are population starting points. Body size, heat, intensity, and GI history change tolerance. “More carbs” is not always better if absorption fails — unfinished gels in the trash help nobody. Watch calorie burn is often high; do not match every estimated calorie with food mid-run. Medical GI issues need clinician input, not blog macros.
Gut-Training Decision Rule
If a long run is primarily aerobic volume, prioritize finishing the planned carbs without GI distress — slow the pace before you abandon the fueling rehearsal. If GI fails twice on the same product/timing, change one variable only (dose, timing, or product), then retest. Never debut a new gel brand at the marathon start line.