Ultra Running Fueling: How to Eat, Drink, and Perform Without Bonking Ultra running doesn’t fail because people aren’t tough enough.  It fails because fueling breaks down—too little, too late, or the wrong approach entirely. If you’ve ever bonked, cramped, lost your appetite, or watched your pace fall apart late in a long run or race, this isn’t a grit problem. It’s a nutrition strategy problem. This guide covers exactly how to fuel for ultra running, based on physiology, not trends—so you can train consistently, race strong, and recover faster.

Most ultra runners need 200–350 calories per hour, depending on: • Body size • Intensity • Terrain • Temperature • Fuel tolerance Trying to “wing it” or under-fueling early almost always leads to: • Energy crashes • GI distress later • Poor decision-making • Dramatic pace drop-offs Key principle:  👉 You can’t “catch up” on calories once you’re behind. Start fueling early and stay consistent.

Instead of large, infrequent feedings, aim for: • Every 20–30 minutes • Smaller, repeatable amounts This keeps: • Blood sugar stable • Gut workload manageable • Energy output consistent Think drip-feed, not feast-or-famine.

In the 24–48 hours before your race, the goal is: • Full glycogen stores • Calm digestion • Familiar foods Focus on: • Carbohydrates you tolerate well • Moderate protein • Lower fat and fiber than normal This is not the time to experiment with: • New supplements • Extreme carb loading • “Clean eating” rigidity Boring works.

Your gut is trainable—just like your legs. To improve tolerance: • Fuel during long training runs • Use race-day foods in training • Practice fueling at race intensity • Avoid saving all fueling practice for race day Most GI issues come from lack of practice, not weak stomachs.

Bonking happens when: • Glycogen runs low • Blood sugar drops • The brain reduces output to protect you To prevent it: • Fuel early (within first 30 minutes) • Fuel consistently • Don’t rely solely on fat adaptation • Adjust intake upward as intensity rises Even fat-adapted athletes still need carbs at race effort.

Cramps are rarely caused by just one thing, but low sodium plus fatigue is a common contributor. General guideline: • 300–700 mg sodium per hour • Increase in heat or heavy sweating Drink to support fueling—not to chase hydration numbers. Clear urine is not a performance metric during ultras.

Hot conditions: • Higher fluid and sodium needs • Easier-to-digest fuels • Smaller, more frequent intakes Cold conditions: • Appetite often drops • Fuel freezes or becomes unpalatable • Energy needs remain high Plan fuels you’ll actually eat when conditions are uncomfortable.

Yes—every long run is a fueling rehearsal. Practice: • Timing • Quantities • Food forms • Hydration strategy Race day is not the place to “see what happens.”

1. Waiting until they’re hungry to eat 2. Underfueling early to “save calories” 3. Avoiding carbs out of fear of GI issues 4. Not practicing nutrition during training 5. Overcomplicating fueling with too many products Simple, consistent strategies outperform complex plans every time.

If you want a starting point: • Calories: 200–300/hr • Carbs: Primary fuel source • Protein: Small amounts on long efforts • Fat: Minimal during high intensity • Sodium: 300–700 mg/hr • Timing: Every 20–30 minutes Adjust based on your body—not dogma.

Ultra running rewards preparation, not punishment. The athletes who finish strong aren’t tougher—they’re better fueled, more consistent, and less reactive when things get hard. Fuel early. Fuel often. Practice relentlessly. That’s how you go long.