When should you eat during a half marathon?

January 7, 2026 •

5 min read

Most runners' bodies can only store enough glycogen for about 90 minutes of high-intensity exercise, a finite fuel reserve that makes a mid-race fueling strategy essential for a successful half marathon finish. Proper timing can mean the difference between hitting a new personal best and hitting the wall.

Quick Summary

This guide outlines the science of mid-race nutrition, detailing the optimal timing and types of carbohydrates to consume. A solid fueling plan is critical to prevent glycogen depletion, maintain energy, and finish your race strong and steady.

Key Points

Start Fueling Early: Begin consuming carbohydrates between 30 and 45 minutes into your run, before your glycogen stores are depleted.
Fuel Consistently: After the initial dose, aim for consistent intake of 30-60 grams of carbohydrates every 30-45 minutes to maintain energy levels.
Pair Fuel with Water: Always consume energy gels and chews with water to aid digestion and prevent stomach upset.
Practice Your Strategy: Use your long training runs to test your specific fueling products and timing. Never try new foods on race day.
Prioritize Simple Carbs: Opt for easy-to-digest, simple carbohydrates like those found in energy gels, chews, or sports drinks for the fastest absorption.
Listen to Your Body: Adjust your fueling based on individual tolerance, course conditions, and how your body responds during training and the race itself.

The Science of Fueling: Why Mid-Race Nutrition Matters

When you run, your body uses two primary fuel sources: stored carbohydrates (glycogen) and fat. Your glycogen stores, located in your muscles and liver, provide a readily available source of high-octane energy, crucial for maintaining a fast pace. The body's ability to efficiently break down fat for fuel is slower, and at higher intensities, it cannot keep up with demand. For most runners, these glycogen reserves are sufficient for approximately 90 minutes of continuous running.

If you anticipate finishing your half marathon in longer than 75 to 90 minutes, you will inevitably deplete your body's glycogen stores, leading to a state commonly known as 'hitting the wall'. To prevent this performance-crushing fatigue, it is critical to top up your carbohydrate supply during the race. By consistently ingesting easy-to-digest carbohydrates, you provide your body with a steady trickle of fuel, preserving your stored glycogen and allowing you to maintain your effort level all the way to the finish line.

Your Half Marathon Fuelling Timeline

Pre-Race Prep

Your mid-race strategy begins well before the starting gun fires. You should practice your fueling plan during your long training runs to ensure your stomach can handle it. This involves carb-loading in the 24-48 hours prior, eating a balanced breakfast of high carbs and low fiber 2-4 hours before the race, and having a small, easily digestible snack 15-20 minutes before the start.

Fueling During the Race

The most important rule is to start fueling before you feel depleted. Waiting until you feel hungry or weak is already too late, and your performance will suffer.

Start Early: Begin consuming fuel between the 30 and 45-minute mark of your race. For most runners, this is a good time to take your first energy gel or chews, often coinciding with the first available aid station. This kickstarts the fueling process before your primary energy stores begin to dip.
Fuel Consistently: After your first dose of fuel, aim for consistent intake every 30 to 45 minutes thereafter. Establishing a routine is key. Using a running watch to set a timer can help you stay on track, especially as your focus wanes toward the later miles.
Target 30-60g of Carbs per Hour: The general guideline is to consume 30-60 grams of carbohydrates per hour of running. Your individual needs may vary based on your body weight, pace, and intensity. Practice different amounts during training to find your sweet spot.
Pair with Hydration: Always consume gels and chews with water to aid digestion and absorption. Taking them with a sports drink, which also contains sugar, can overload your system and cause gastrointestinal distress.

Hydration: Your Other Critical Fuel

While this article focuses on food, proper hydration is an inseparable part of your fueling strategy. Dehydration can severely impact performance and digestion. Many sports drinks offer a mix of carbohydrates and electrolytes, simultaneously addressing two needs. However, if you are consuming gels, stick to water to avoid excess sugar intake. You can learn more about proper fueling by visiting the Sports Dietitians Australia website, an authoritative source on endurance nutrition: Sports Dietitians Australia.

Choosing Your Mid-Race Fuel

Your choice of fuel comes down to personal preference and what you've practiced with during training. The best options are those high in simple, fast-absorbing carbohydrates.

Energy Gels: A popular and convenient option, offering a concentrated dose of carbohydrates. They are easy to carry and require minimal chewing, but must be consumed with water.
Energy Chews or Gummies: A good alternative for those who dislike the texture of gels. They provide carbohydrates in a solid, bite-sized form. Take them with water.
Sports Drinks: Offer carbohydrates and electrolytes simultaneously. Ensure you know what brand is on the course or carry your own, as some brands can cause stomach issues.
Real Food: Options like dried fruit (dates, raisins) or small pieces of banana can work. However, they are heavier, harder to digest while running, and can cause stomach upset if not properly practiced.

Comparison of Fueling Options


Feature	Energy Gels	Energy Chews	Sports Drinks	Real Food
Convenience	Excellent (small, easy to carry)	Good (solid, chewable)	Variable (requires carrying a bottle or using aid stations)	Poor (bulkier, requires chewing)
Absorption Speed	Very Fast	Fast	Fast	Slower (due to fiber/fat)
Carb Quantity	Consistent (pre-measured)	Consistent (per chew)	Varies by brand/concentration	Inconsistent (depends on food type)
Risk of GI Issues	Low-Moderate (if taken with water)	Low-Moderate (if taken with water)	Moderate (sugar concentration)	High (fiber, fat can cause issues)
Requires Water	Yes, highly recommended	Yes, highly recommended	Included	Yes

Developing Your Personal Fueling Strategy

Practice is Non-Negotiable: Use your long training runs as a dress rehearsal for race day. Test the specific products you plan to use, noting how your body reacts. Do not try anything new on race day, no matter how appealing the samples are at the expo.
Calm Your Stomach: Nerves can affect digestion. If you tend to get an upset stomach, stick to the lowest recommended amount of carbs per hour and prioritize hydration. Choose well-tolerated, simple carbohydrates.
Factor in the Course: A hilly course will increase your carbohydrate burn. Plan to fuel slightly more frequently before major climbs. If it's a hot day, your hydration needs will be higher, and electrolytes become more important.
Listen to Your Body: While general guidelines are helpful, every runner's body is different. Pay attention to how you feel and adjust your plan accordingly. Some people tolerate more fuel than others; some find real food is better, while others can only handle gels.

Conclusion: Fueling Your Way to the Finish Line

Knowing when to eat during a half marathon is a cornerstone of a successful race day. By starting your fueling within the first 45 minutes and continuing with a consistent intake of 30-60 grams of simple carbohydrates every 30-45 minutes, you can outsmart glycogen depletion. Practice your strategy diligently during your training runs, listen to your body, and never experiment on race day. By doing so, you can ensure you have the energy needed to power through the final miles and cross the finish line with a smile on your face.

Frequently Asked Questions

Yes, absolutely. In fact, if you anticipate finishing in over 75-90 minutes, fueling is even more critical. Slower runners spend more time on the course and will deplete their glycogen stores without proper mid-race nutrition.

Take your first gel between 30 and 45 minutes into the race. This proactive approach ensures your body receives carbohydrates before your stored glycogen levels start to drop, helping to maintain your energy from the beginning.

If you forget to eat, you risk running out of glycogen, a phenomenon known as 'bonking.' This results in significant fatigue, a drastic drop in pace, and a feeling of heavy legs as your body struggles to use fat as its primary fuel source.

The choice between chews and gels is largely based on personal preference and what you've practiced. Chews are a good alternative for those who dislike the sticky texture of gels. Both are effective, fast-absorbing sources of carbohydrates.

The amount of fluid you need varies based on sweat rate and conditions. A general guideline is to drink at every aid station, or aim for 500-1000ml of fluid per hour. If using gels, make sure to wash them down with plain water.

If you plan to use the on-course sports drink, you must practice with that specific brand during your long training runs. Different brands have different formulations that can cause stomach upset if you aren't used to them.

Yes, but be cautious. Whole foods are heavier and slower to digest, which can cause gastrointestinal distress during a run. This is especially true for faster-paced efforts. Always practice with real food during training to ensure your body tolerates it.

Nausea can be caused by over-consuming sugar or dehydration. If you feel sick, slow down, sip plain water, and consider skipping your next planned fuel intake. Resume a lighter fueling plan only when your stomach feels settled. Always focus on hydration.