Fueling During Long Workouts: What to Eat Hour by Hour

You’ve probably heard the saying: “You don’t win races in training — you win them by fueling right.”

It’s true. Your body can store only about 90 minutes of glycogen, which means anything longer than that — long runs, bike rides, or brick sessions — requires smart fueling.

Get it wrong, and you bonk. Get it right, and every long workout becomes a chance to train your gut, sustain energy, and finish strong.

Let’s break down exactly how to fuel during long workouts — hour by hour, based on sports nutrition research and the real-world habits of elite endurance athletes.

Your body relies on glycogen (carbs stored in muscle) and fat for energy. At easy intensities, fat contributes more; as intensity rises, carbs become the dominant fuel.

The problem? Glycogen stores are limited. Once they run out, your pace plummets, concentration fades, and your muscles revolt — the dreaded bonk.

The solution is simple: steady carb intake. Carbs delay fatigue, sustain blood glucose, and help your brain stay sharp during hours of effort.

Your fueling rate depends on workout intensity and duration. Here’s a guideline based on current research (Asker Jeukendrup, 2025):

For context, one gel delivers roughly 25–30 g of carbs. If you’re aiming for 60 g/hour, that’s about two gels or one bottle of carb drink per hour.

Use this template to keep energy consistent across a three-hour endurance session.

Cyclists can mix in solid carbs like energy bars or rice cakes for variety, while runners should lean on gels, chews, or drink mixes for easier digestion.

Pro tip: Your gut can adapt. Practice this plan weekly to train carbohydrate absorption up to 90 g/hour.

Fueling is more than carbs — hydration drives performance and keeps your gut absorbing fuel efficiently.

• Drink 400–800 ml of fluid per hour (13–27 oz) during long workouts.
• Aim for 400–800 mg sodium per hour based on sweat rate and temperature.
• Combine fluids with carbs to support absorption and prevent gut sloshing.

Weigh yourself before and after key workouts: every pound lost equals roughly 450 ml (15 oz) of fluid to replace.

• 🏃 Long Runs: Use gels or chews every 20–30 minutes with sips of sports drink to hit 30–60 g carbs per hour.
• 🚴 Long Rides: Mix bottles, gels, and small solids like rice cakes to reach 60–90 g carbs per hour on rides over two hours.
• 🏊 Brick or Triathlon Sessions: Front-load carbs on the bike, then maintain steady gels and fluids on the run to protect pacing.

Fueling well is a skill. Your gut needs rehearsal to tolerate higher carb loads without distress.

• Start with 30 g/hour and increase by 10–15 g each week until you reach your race target.
• Use the same gels, drinks, and chews you plan to race with to minimize surprises.
• Fuel early — never wait until you feel tired or hungry to start eating.

• Waiting too long to start fueling and falling behind on carbs.
• Drinking only water and diluting sodium, risking cramps or hyponatremia.
• Overloading the gut late in the workout instead of spacing carbs evenly.
• Skipping carb training so the gut struggles on race day.

MAVR makes endurance fueling simple by turning guidance into daily targets you can execute with confidence.

• Imports your training calendar from supported apps to set fueling cues automatically.
• Calculates carb, fluid, and sodium targets for every long workout and race simulation.
• Builds hour-by-hour fueling plans so you can rehearse every gel, bottle, and chew.
• Generates race-day strategies for carb loading, in-session fueling, and hydration.