What a Professional Dietitian Wants You to Know About Eating Before Running

Thank you to OCS blog contributor, registered dietitian and Marine spouse Cortney Berling, MPH, RD, CDE. Sign Up for her OCS Prep Nutrition Program here to improve your fitness and knowledge with live group coaching (limited availability)

Pre-Run Nutrition 

What you’re eating before running can make a significant difference in your training and PFT score. 

Every athlete is different, therefore pre-run nutrition choices should be individualized. It is important to remember that the stomach is a muscle and needs to be trained. If you currently do not eat anything before you run, try starting with something small and simple such as half a banana. As you teach your stomach to tolerate food before training you will be able to increase your nutrition, and you will have significantly more energy on your training runs! 

The main goals of a pre-run snack are to:

1.) Provide fuel so you are fully energized 

2.) Minimize muscle breakdown 

3.) Make you feel good mentally & physically

How much should I eat before I run? 

Consider the amount of time your body needs for digestion, the duration, and the intensity of your run. As a good rule of thumb, you should consume about 25-40 grams of carbs for each lb of body weight before a 45-60 minute run. (Hansen, 2018). Keep it simple and easy to digest. The perfect pre-run snack can be found through trial and error. Try simple carbohydrates such as a banana, dates, 1-2 slices of toast, animal crackers, or a sports drink. Find which option works best for your body! You will know if it is “working” if you don’t get stomach cramps, you don’t have to make a bathroom stop, and you feel energized!

More fuel means more fun when you run in the Marines, right?

Do I only need carbohydrates before I run? 

Carbs are king before a run, but a small amount of protein will be helpful to balance your blood sugar and keep you from becoming hungry during your run. Aim for 5-10 grams of protein in your pre-run snack. This can be achieved with a tablespoon of peanut butter.

Does eating before a workout really make a difference?

Yes! A study looked at how long cyclists could maintain a moderate pace after eating breakfast vs not eating breakfast. The result was clear, the day they ate a carbohydrate based breakfast they were able to ride 15% harder in the last 45 minutes of their workout. (Schabort, Bosch, Weltan, & Noakes, 1999)

Carbohydrates are fuel for your “engine” (i.e., your muscles). And, the harder your engine is working, the more carbs you need to keep going. If you are not eating enough carbohydrates you may experience: increased perceived exertion, lack of energy, no glycogen (stored form of carbohydrates) which keeps you from being able to build upon mileage/intensity, injury and/or illness

Ideas for pre-workout fuel:

  • 2 dates with peanut butter 
  • Banana with peanut butter 
  • Kodiak Cakes pre-made waffles 
  • LaraBar, GoMacro Bar, Nature’s Bakery Fig Bar, Perfect Bar 
  • A peanut butter and banana sandwich
  • Toast with jam/honey
  • Sports drink such as Gatorade

Is there anything specific I should avoid before my run?

  • High fiber foods such as bran cereal, raw vegetables, beans, etc. Fiber slows down digestion, which is normally a good thing. However, in a pre-run snack/meal it may lead to stomach troubles. 
  • For most people milk or dairy products don’t usually sit well in the stomach before a run
  • Spicy foods which could cause heartburn

Pro tip: Never ever try anything new on race day! Practice what you will eat on PFT day. Remember, it takes time to adjust to eating before exercise so start small and build up!


The vast majority of nutrition is out of your control. You will eat when you are told to eat. Sometimes your “chow window” is shortly before your physical training, so it is in your best interest to train your stomach to tolerate food prior to exercise before you get to OCS!


You will be back on your own. You are able to buy sports drinks, nutrition bars, etc to store in the barracks. TBS is even more physically demanding so pre, during, and post workout nutrition is important to fuel your performance.

By Cortney Berling, MPH, RD, CDE

Cortney is the founder of Eat Well. Perform Better LLC, a performance nutrition & run coaching business designed to help athletes learn to fuel & train in a sustainable way to achieve their goals. 

Cortney is a Registered Dietitian, Certified Diabetes Educator, and Running Coach. She holds a Bachelor’s of Science in Dietetics and a Masters in Public Health. She ran track and cross country at The University of Cincinnati. She has continued to run competitively and has finished 4th at the Cleveland Marathon in a time of 2:57. 

She is married to a USMC Officer who spent 3 years as the OSO at OST Amherst. Though Cortney has not been to OCS, she certainly understands the demanding nature of OCS and the training it takes to succeed in this environment. 

Sign Up for the OCS Prep Nutrition Program here

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Hansen, J. (2018, September 4). These are the Carbs You Should Eat Before a Workout. Retrieved October 06, 2020, from https://www.teamusa.org/USA-Triathlon/News/Blogs/Fuel-Station/2018/September/04/These-are-the-Carbs-You-Should-Eat-Before-a-Workout

Schabort, E. J., Bosch, A. N., Weltan, S. M., & Noakes, T. D. (1999). The effect of a preexercise meal on time to fatigue during prolonged cycling exercise. Medicine & Science in Sports & Exercise, 31(3), 464-471. doi:10.1097/00005768-199903000-00017

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