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Fueling practice guide

A training-first fueling guide: how to pick a starting carb target, build a repeatable schedule, and practice so race day isn’t an experiment.

Last updated/Feb 03, 2026, 02:17 PM

Fueling is a skill

Fitness is only half the marathon. Execution is the other half.

If you under-fuel, you don’t just “feel bad” — you slow down, your form collapses, and cramps/GI problems become more likely.

The simplest plan that works

  1. Pick a starting carb target you can tolerate.
  2. Turn it into a schedule (every 15–30 minutes).
  3. Practice it on long runs until it’s automatic.

How to practice (without blowing up your gut)

  • Practice at easy-to-steady effort first.
  • Keep the same products for a few long runs before you change anything.
  • If you get GI issues: reduce dose size, increase spacing, and simplify.

Hydration: avoid extremes

Drink enough to stay stable, but avoid over-drinking. Practice a plan in training and adjust for heat and sweat rate.

Checklist

Do this, not that

Fueling practice checklist

  • I will practice fueling on long runs (not just on race week).
  • I start fueling early (before hunger hits).
  • I use a schedule (every ____ minutes), not vague intention.
  • I keep products consistent until tolerance is proven.
  • If GI issues appear, I change one variable at a time.
  • I also practice hydration in heat (not just carbs).
  • I avoid trying new products in the final 2 weeks before race day.
  • I have a plan B if I can’t stomach gels (drink mix / chews / simpler dose).

Coaching beta

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FAQs

What carb target should I use?

Start with a conservative target you tolerate, then adjust in training. Gut tolerance varies — race day is not the day to find out.

When should I start fueling?

Early. Waiting until you feel depleted is usually too late. Practice starting within the first 30 minutes.

Do I need sodium?

It depends on conditions and your sweat rate. Practice hydration in training and avoid extremes; if you have medical conditions, consult a professional.

Keep going

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