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Gut training.

PLACEHOLDER — Matt writes the hero. Enter your race date and current fuelling rate for a week-by-week ramp toward your race-day carb target, with each number marked evidence or convention.

  • A dated week-by-week schedule to your race
  • Every number marked evidence or convention
  • Tells you honestly if you're out of runway
  • Free, and you see your plan without signing up

Racing soon and just need the pre-race plan? Endurance carb loading calculator.

Pick your race day - it decides whether you can reach your target.

Never practised fuelling? Use 30.

Auto picks the gentler pace your runway allows.

Waiting on inputs

Enter your race date and current fuelling rate to see your plan.

Read next

Fuelling, worked out in practice.

The case study behind this calculator, when carb timing actually matters, and race-day fuelling for shorter events.

FAQ

Gut training, answered.

How do I train my gut for a marathon?
PLACEHOLDER — Matt writes. (Sourced: repeated exposure to your target carb rate during long sessions raises absorption and cuts GI distress; Costa 2017 showed this over ~2 weeks at 90 g/hr.)
How many carbs per hour should I train to?
PLACEHOLDER — Matt writes. (Sourced: 90 g/hr is the evidence-backed ceiling for most; 120 g/hr only for long events in already gut-trained athletes.)
How long does gut training take?
PLACEHOLDER — Matt writes. (The one trial ran 2 weeks at target; the longer week-by-week ramp is convention, not tested. Honest answer: as little as ~2 weeks of exposure at target, more runway is gentler.)
Can I train my gut in two weeks before a race?
PLACEHOLDER — Matt writes. (Sourced: the only trial WAS two weeks of repeated exposure at target, so a short runway points to the evidence-backed core rather than a truncated ramp.)
What carbs are best for high-rate fuelling?
PLACEHOLDER — Matt writes. (Sourced: 2:1 glucose:fructose above 60 g/hr; nearer 1:0.8 approaching 120 g/hr.)
How do I stop GI problems when running?
PLACEHOLDER — Matt writes. (Back off to the last tolerated rate, cut fibre/FODMAPs 24-48h before, train fed; symptoms are trainable down per Jeukendrup 2017.)

Also in the calculators

Pre-race fuelling: carb loading or Hyrox. For weekly macros, the macro calculator.

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Five free calculators29 kitchen-tested recipesCited articles on training and eatingNo paid membershipReal food, real macrosFive free calculators29 kitchen-tested recipesCited articles on training and eatingNo paid membershipReal food, real macrosFive free calculators29 kitchen-tested recipesCited articles on training and eatingNo paid membershipReal food, real macrosFive free calculators29 kitchen-tested recipesCited articles on training and eatingNo paid membershipReal food, real macros