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The Ultimate Marathon Fueling Guide: Avoid Bonking and Shave 10+ Minutes Off Your Marathon
Jonah Rosner
October 31, 2024
The Ultimate Marathon Fueling Guide: Avoid Bonking and Shave 10+ Minutes Off Your Marathon
Estimated read time: 3.27 minutes
Hey Performance Nerds! Jonah here. 🤓
This weekend, I lost in pickleball to an 89-year-old named Stanley at my local senior center. He calls me "Turtle" now for being so slow. If only he knew.
Let’s dive in! Today, you'll learn how to fuel your fastest marathon:
🏃♂️ Why gels are essential for your best race
🔍 The top (and worst) gels out there
📏 How many gels to take on race day
🧪 How to train your stomach to handle gels
Enjoy this week’s guide, the nerdy question, and my favorite science finds.
Don’t forget to reply if you need advice for your upcoming race! 🏃♀️💨🧪
Why Do You Need To Take Gels?
Bonking. Enough Said. Mic Drop. 🎤💥
Bonking happens when you run out of energy, causing your blood sugar to crash.
Your body’s energy stores (glycogen) last about 90 minutes in a race. For races longer than 90 minutes, you need carbs to keep your speed. ⚡️
In-race carbs keep blood sugar steady, prevent bonking, and give you extra energy to finish strong. 💪
What Are The Best Gels?
You don’t see Kipchoge snacking on apples mid-marathon.
Spoiler: neither should you. 🍎🚫
Skip whole-food carb gels and solids (like bars). They digest slowly and can lead to stomach issues. 😬
Least Favorite Gels
Yep, I’ll call out bad science when I see it. Let’s be real—I’m not getting any brand deals anytime soon. Around here, it’s all about real science and helping you crush your goals. Augie, my dog, might need to pick up a side job to pay the rent. 🐶💸
Choose a fast-digesting gel. These gels provide quick energy and reduce the risk of stomach issues.
Look for gels made mostly of maltodextrin/glucose with some fructose.
The Magical Ratio
Want to keep up with Augie (my dog) when he spots a squirrel? Grab a gel with both glucose and fructose!
Your stomach has special transporters to absorb carbs, but they have limits.
Glucose transporters can handle about 60 grams of carbs per hour. Fructose uses a different transporter, letting you take in even more carbs.
Gels with both glucose and fructose let you absorb over 60 grams per hour—giving you more energy for your race!
Look for a gel with a 1:0.8 ratio of glucose to fructose - 1 gram of glucose for every 0.8 grams of fructose.
This ratio:
Maximizes carb absorption
Reduces stomach discomfort during races
Favorite Gels
These gels contain mostly glucose/maltodextrin and fructose, making them fast-digesting with an ideal glucose-to-fructose ratio. Bye-bye, bonking!
How Many Gels Should You Take?
Recent evidence shows that 60-90 grams of carbs per hour from a glucose/maltodextrin-fructose gel can boost marathon performance.
This intake helps maintain glycogen stores, giving you steady energy for a faster race.
New to fueling? Start slow and gradually build to 60-90 grams/hour to avoid stomach issues.
60-90 Grams Per Hour Gel Guide: Everyone’s needs vary—find the carb intake rate that works best for you!
How Often Should You Take Gels?
Many runners wait until the second half of the race to start taking gels. Big mistake.
Start fueling early to preserve liver carbs and keep blood sugar stable. Bye-Bye bonking!
Research recommends taking gels every 20-30 minutes, starting from the beginning of your race.
How many you need depends on the gel's carb content and your goals. Most gels have 20-30 grams, so aim for 3-5 gels per hour.
Sample Gel Strategy
Sample Race-Day Gel Strategy: Options for 75g and 90g per hour. A lower carb rate is ideal for those new to fueling. By gel #8, you can start dreaming about that post-race pizza! 🍕
How To Train Your Gut For Gels
Pro Tip: Trying 5 gels per hour for the first time on race day? Big no-no. 🚫
Practice your gel strategy well before race day. Research shows this builds your stomach’s tolerance to gels.
How to Practice:
Start 8-10 weeks out ⏳
Test your favorite gel on long runs 🏃♂️
Gradually work up to your target hourly carb intake ⚡️
Try going slightly over your target for a week or two
10-Week Stomach Training Plan
Week | Carbs per Hour (g) | Notes |
1 | 45 | Start with 45g carbs/hr |
2 | 45 | Stay with 45g carbs/hr |
3 | 60 | Increase to 60g carbs/hr |
4 | 60 | Stay with 60g carbs/hr |
5 | 75 | Increase to 75g carbs/hr |
6 | 75 | Stay with 75g carbs/hr |
7 | 90 | Reach 90g carbs/hr target |
8 | 90 | Stay with 90g carbs/hr target |
9 | 120 | Go over target with 120g carbs/hr |
10 | 90 | Back down to 90g carbs/hr (race prep) |
Practical Summary
Carb Intake: 60-90g of carbs per hour from a glucose/maltodextrin-fructose gel to prevent bonking
Gel Type: Use fast-digesting gels with a 1:0.8 glucose-to-fructose ratio for better absorption and less stomach discomfort.
Fueling Strategy: Start fueling early. Take a gel every 20-30 minutes. Most gels have 20-30g carbs, so aim for 3-5 gels per hour.
Train Your Gut: Practice 8-10 weeks before race day, gradually reaching target intake to build tolerance.
Ultimate VO2 Max and Lactate Thresholds Guide
Did you miss my video about the Ultimate VO2 Max and Lactate Thresholds Guide? You can find it below!
I won’t lie. These videos take me a while to make. If you find it helpful, share it on your story or with a friend. It helps me a ton!
Are You a True Running Nerd? Prove it.. 🧐
Welcome to the prove you’re a nerd section. Each week I ask a question about a common running science myth.
Answer correctly, and you’ll be entered into a weekly raffle to win a package of Jonah’s favorite supplements from Raw Nutrition.
What is the most effective type of lifting to improve distance running performance. |
Last Week’s Results
You guys nailed it! 🤓
100% correct—no specific shoe type has been directly linked to injury risk. The key is to introduce new shoes gradually! Add them into your rotation for a few miles at a time and build up from there. 👟🚀
🟨⬜️⬜️⬜️⬜️⬜️ Highly cushioned maximalist shoes (16)
🟨🟨⬜️⬜️⬜️⬜️ Minimalist (barefoot) shoes (37)
🟨⬜️⬜️⬜️⬜️⬜️ Super Shoes (14)
🟩🟩🟩🟩🟩🟩 No shoe type has been linked to increased injury risk. The biggest factor may be switching shoes too quickly before you're used to them (93)
Nerdy Finds of the Week 📚🧑🔬
This section includes my favorite research, podcasts or books about running/lifting science.
Research Paper: High or hot-Perspectives on altitude camps and heat-acclimation training as preparation for prolonged stage races
This paper focuses on the performance benefits of heat or altitude before longer races. Some great practical insights.
Podcast: A Guide to Shoe Cushioning: Compliance Resilience and How it Influences Your Joints and Muscles
Doctors of Running is my favorite podcast for all things running shoes. This is a good episode about the science of cushioning and how it changes the way you run!
Blog: Lactate for Endurance Training: What is it?
Good overview of what lactate actually is and how it might be used in endurance programs.
Don’t forget: You + Science = AWESOMENESS 😎
Yours in science,
Jonah
P.S. - We have a crew of 5,500+ nerds here who are running FAST using science.
Did you need running science advice for your upcoming race? 🏃♀️💨🧪
Reply with your question, Augie and I (pictured below) will get back to you with specific race day advice based on your goals!
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