What to Eat Before a Half Marathon

When you run a half marathon, you are running at a relatively moderate intensity for a prolonged period of time. For most runners, half marathon pace is above aerobic threshold but below lactate threshold – an intensity where your body oxidizes more carbohydrates than fat for energy. Your body will use both glucose (carbs in the bloodstream) and glycogen (carbs stored in the muscle) to produce energy during a half marathon. Without enough carbohydrates, you will experience more fatigue and miss your performance potential. 

This article explores how to fuel during a half marathon. However, mid-race fueling is only part of the equation. In order to run your best half marathon, you will want to have a nutrition strategy that encompasses eating before and during the race. This article guides you through what to eat before a half marathon.

Should You Carb Load before a Half Marathon?

Runners typically think about carbohydrate-loading (carb load) before a marathon. However, carb loading should be performed before any race lasting longer than 90 minutes. For a majority of recreational runners, carb loading before a long-distance race entails increasing carbohydrate intake to 7-10 g of carbohydrate per kilogram of body weight per day in the three days leading up to a race. Alternatively, a shorter carb load for 2 days can be performed if carb intake is increased to 10-12 g/kg/day. 

While you will still eat fiber, chose low-fiber carbohydrates when increasing your intake during the carb-load. Simple carbohydrates store more readily as glycogen. Additionally, if you increase your carbohydrate intake with fibrous carbohydrates, you increase your fiber intake. Too much fiber intake before the race can leave you feeling bloated and increase the risk of GI distress on race day. 

A carb load increases the body’s glycogen stores by up to 200-300%. Larger glycogen stores can improve performance and delay fatigue in long-distance races. 

If you anticipate finishing your half marathon in under 90 minutes, you will still want to ensure you have adequate carbohydrate intake in the days leading up to the race. For moderate- to high-volume athletes, this is 6-10 grams of carbohydrate per kilogram of body weight per day. 

What to Eat Before a Half Marathon

When you sleep, your body uses approximately half of its glycogen stores. For optimal performance, you need to eat carbohydrates before your race – even if you have been carb-loading. Depending on how early your race is, you want to eat approximately one to three hours before the race start. The less time you have to digest, the lower the amount of carbs/calories you will eat. 

• 1-3 g carb per kilogram of body weight (or roughly 300-700 kcal, mostly carbs)
• Small amount of protein (<20 g) for satiety if desired and tolerated
• Minimize fat and fiber
• Drink 16-24 ounces of sports drink or water

The exact foods you chose to eat will vary individually. Sample pre-race meals include:

• A plain bagel and banana (a bit of peanut butter if desired)
• Frozen waffles
• Quick oats (avoid this if sensitive to fiber)
• Rice and a banana
• A couple of slices of white bread with jam and a banana
• Toaster pastries plus a banana

Should You Have Coffee Before a Half Marathon?

Caffeine can function as an ergogenic aid – meaning it improves performance while reducing the perception of effort. However, caffeine supplementation is not appropriate for every runner. 

Use caffeine before your half marathon if:

• You regularly drink coffee or tea in the mornings
• You tolerate caffeine well without adverse effects

Skip caffeine before your half marathon if:

• Caffeine gives you the jitters (anxiety, shakiness, palpitations, etc)
• Caffeine irritates your GI system (you get nausea or diarrhea from it)
• You do not regularly drink caffeine and have never tested it before a long run

If you do consume caffeine before a race, the International Society of Sports Nutrition recommends 3-6 mg of caffeine per kilogram of bodyweight, approximately an hour before exercise. If you are racing at high altitude or in the heat, you will want to aim for 4-6 g/kg. 

Foods to Avoid Before a Half Marathon

In the days leading up the race, avoid any foods that are irritating to you. These foods will vary for individuals. For example, if dairy does not sit well with you, avoid dairy products before your race. Some runners find certain vegetables such as cauliflower and broccoli can cause gas and bloating. If that happens to you, you may choose to opt out of those before the race. 

In your pre-race meal, avoid fiber and fat. Both fiber and fat are slower to digest, which may cause GI upset for some runners.

Example of What to Eat Before a Half Marathon

That’s a lot of information – let’s put it into practical terms. This example uses a 60 kg runner preparing for a 1:45 hour half marathon. 

Carb-load: 480-600 grams of carbs per day for 3 days

Pre-race breakfast: 75-180 grams of carbs (2 Nature’s Path toaster pastries (78 g carb) + 1 banana (25 g carb) at 2 hours before race), 20 oz Skratch Labs Hydration mix, and 240 mg caffeine

Disclaimer: I am currently working on my MS in Applied Exercise Science with a concentration in Sport Nutrition and preparing to sit for my CISSN. However, I am not a registered dietitian. This is generalized nutrition advice and may not be catered to an athlete’s individual needs.

References:

Antonio, J., Kalman, D., Stout, J., Greenwood, M., Willoughly, D., & Haff, G. (2008) Essentials of sport nutrition and supplements. Humana Press.

Casazza, G. A., Tovar, A. P., Richardson, C. E., Cortez, A. N., & Davis, B. A. (2018). Energy Availability, Macronutrient Intake, and Nutritional Supplementation for Improving Exercise Performance in Endurance Athletes. Current sports medicine reports, 17(6), 215–223. https://doi.org/10.1249/JSR.0000000000000494

Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., Grgic, J., Schoenfeld, B. J., Jenkins, N., Arent, S. M., Antonio, J., Stout, J. R., Trexler, E. T., Smith-Ryan, A. E., Goldstein, E. R., Kalman, D. S., & Campbell, B. I. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1), 1. https://doi.org/10.1186/s12970-020-00383-4