If you’ve ever had an otherwise-perfect race, long run, or workout ruined due to GI distress or an uncomfortable stomach, you know how important it is to nail your race-day nutrition.

While it’s perfectly normal to be unsure about nutrition, fueling, and marathon training, the right nutrition strategy on race day can really make a difference. A 2023 study analyzing fueling strategies for runners found that per each additional 100-calorie gel consumed, runners were able to run 0.5 to 0.7 kilometers further in the same amount of time. This amounted to a 7.75% increase in speed compared to runners who did not take nutrition. 

Here’s what the science has to say about marathon training and fueling:

• Carbohydrates: When it comes to carbs, the length of your activity will dictate how much you should be ingesting. For events lasting less than 60 minutes, don’t worry about taking in extra carbs. However, for activities that last between 1 and 2.5 hours, 30-60 grams of carbs per hour is recommended, ideally consumed every 10-15 minutes in a 6-8% carb solution (like in a sports drink). For events longer than 2.5 hours, 60-70 grams per hour (and up to 90 grams per hour!) are recommended. 

While the above research is particular, it’s important to remember that every body is different. Instead of every 10-15 minutes, your body may appreciate 20, 30, or 40 minute intervals. Instead of a carb solution, like a sports drink, you may rather eat gels, chews, or even solid food. 

There’s lots of advice on the internet and from influencers on TikTok and Instagram, but marathon nutrition is very personal. Beyond running a lot of miles during training, it pays to pay attention to what you eat both before, during, and after your run. 

In general:

• Eat or ingest something before you feel hungry during a race or long run. If you wait until you’re hungry, it’s probably too late! 
• Experiment with different gels and electrolyte drinks in the early months/weeks of training, and figure out what you like best. 
• Once you’ve found the nutrition that works best for you, use ONLY that nutrition during the remainder of your training. This will ensure you don’t have any surprises on race day. 
• Plan your pre-run meals ahead of time (this goes for dinner the night before AND breakfast/whatever you eat before a run). Pay attention to how this sits in your stomach, and increase or decrease portions accordingly. 
• Within your training log, add a tab for notes regarding fuel and hydration. Write down your fueling strategy, and how you felt during and at the end of your run. If you’re taking in gels every 30 minutes and feel depleted towards the end of your long run, try increasing the intervals at which you take in nutrition. While the study above does indicate you should be consuming gels every 10-15 minutes, this is an important parameter to personalize as well.
• Pay attention to caffeine content within gels, GUs, and gummies. It’s okay to take in a little bit of caffeine, but monitor how much, and how it affects your performance. 

There’s no one-size-fits-all model for fueling, but the above advice should get you to the starting line. Experiment and figure out the best strategy for you — you’ll thank yourself on race day!