Triathlon
Fueling During Long Workouts: What to Eat Hour by Hour
Avoid bonking on long runs and rides with an hour-by-hour fueling plan, carb targets, and hydration tactics backed by elite endurance research.
Quick answer
Fuel long workouts by taking 30–90 g of carbs and 400–800 ml of fluid every hour, layering sodium and practiced products — MAVR automates the timing and portions for each session.
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.
The Basics: Why You Need to Fuel During Long Workouts
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.
How Many Carbs You Actually Need
Your fueling rate depends on workout intensity and duration. Here’s a guideline based on current research (Asker Jeukendrup, 2026):
| Workout Duration | Carb Target | Example |
|---|---|---|
| <90 minutes | Optional (water only or small snack) | 20–30 g carbs/hr if needed |
| 1.5–2.5 hours | 30–60 g carbs per hour | 1–2 gels/hr or 500 ml sports drink |
| 2.5–4 hours | 60–90 g carbs per hour | 2–3 gels/hr or carb mix + solid fuel |
| 4+ hours | 80–100 g carbs per hour (if trained) | Mix of drink + gels + real food |
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.
Hour-by-Hour Fueling Example (3-Hour Long Run or Ride)
Use this template to keep energy consistent across a three-hour endurance session.
| Time | Fuel | Why It Works |
|---|---|---|
| 0:00 | Small snack 30 minutes before start (banana or gel) | Tops off liver glycogen |
| 0:30 | 25–30 g carbs (gel or drink) | Prevents early glycogen dip |
| 1:00 | 30 g carbs + sip fluids | Keeps blood glucose stable |
| 1:30 | 30–45 g carbs + 250 ml fluids | Delays fatigue mid-session |
| 2:00 | 30–45 g carbs + electrolytes | Replaces sodium lost in sweat |
| 2:30 | 30 g carbs (solid if cycling) | Keeps energy consistent |
| 3:00 | 30 g carbs + water | Finishes strong, avoids bonk |
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.
Don’t Forget Fluids and Sodium
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.
Fueling for Different Sports
- 🏃 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.
Training Your Gut
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.
Common Fueling Mistakes
- 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.
Write Your Plan on Your Bottle
All of this only works if it survives contact with a tired brain three hours in, so make it stupidly simple to follow. Set a recurring beep on your watch every 20-30 minutes as a feed cue — most bonks are really just forgotten feeds — and write your hourly carb and fluid targets on a strip of tape on your bottle or flask. Decide your numbers before you head out: total carbs per hour, how many gels that equals, and roughly how much to drink. When the plan is on the bottle and the watch nags you to eat, fueling becomes a reflex instead of a decision.
Turning your training calendar into those per-session carb, fluid, and sodium numbers automatically — and into a rehearsable hour-by-hour plan — is what MAVR does so you skip the spreadsheet. But the watch alarm and the tape on your bottle are the parts that actually keep you fueled, and they cost nothing.
Fuel smarter. Go longer. Perform better.
Frequently Asked Questions (FAQ)
How many carbs do I need per hour in long workouts?
Most athletes need 30–90 g of carbs per hour depending on workout duration, intensity, and gut training.
When should I take my first gel?
Start around 30 minutes into your workout to stay ahead of glycogen depletion and keep blood glucose steady.
Should I use real food or gels?
Runners should favor gels, chews, or drink mixes, while cyclists can add small solid foods like rice cakes or bars for variety.
What about caffeine?
Caffeine can enhance endurance — try a caffeinated gel mid-session or near the finish if your stomach tolerates it.
Can MAVR build a fueling plan for my long runs?
Yes. MAVR automatically adjusts hourly carb and hydration targets based on upcoming sessions in your training calendar.
Related Reading
Written by
MAVR Sports Nutrition Team
The MAVR sports-nutrition team translates peer-reviewed endurance research (Jeukendrup, Burke, the ISSN) into daily fueling for runners and triathletes.