How To Avoid Stomach Issues While Running

Running is one of the most amazing sports, but it can also be one of the toughest on your body. The creaky knees sore muscles and stomach issues are enough to scare some people away. And while I can’t help you with the first two, I can tell you that stomach issues are not something you just need to suffer through while running. As a matter of fact, gastrointestinal (GI) discomfort is completely avoidable with the right nutrition.

Stomach & GI issues are some of the most common ailments among runners, but they can be solved with proper nutrition. A Registered Dietitian and marathon runner provides tips to do just that! #runner #run #sportsnutrition #runnernutrition

What happens to your stomach during a run?

Blood is an amazing thing because it recognizes where your body has work to do, and it immediately travels to that region. During a run, your blood goes to the the part of the body that is doing the most work–the muscles. Because of this, the blood is diverted away from the stomach, and any food that is in the stomach just sit there. During the constant up and down running motion, any food left in the stomach will be jostled around and cause distress.

Even without food, the physical shaking of the stomach during running is enough to cause distress. Think about if I took your stomach out of your body and shook it up and down constantly for an hour. That’s pretty much what running does to your digestive system. A seasoned runner will eventually adjust to this feeling, but it will definitely cause problems for a new runner.

Lastly, even if you haven’t eaten in a while, your intestines is likely digesting some food. Running causes that food to move quickly through your intestines, which can make you feel like you need to use the bathroom. Unfortunately, this is just a natural occurrence that is less than ideal for runners. That being said, there are things you can do to help combat these issues, such as:

Avoid high fiber foods. A friend of mine recently told me she was so confused because she was eating cereal (necessary carbs) before running, but she was still experiencing constant stomach problems. It turned out that she was eating high fiber cereal. The combination of high fiber foods plus running equals a guaranteed upset stomach. It’s best to avoid foods like cruciferous veggies, beans, bran, and high fiber fruit before a run. And if you’re race, lay off the high fiber foods the day before as well.

Stay properly hydrated. Dehydration can make it difficult for your intestines to absorb food. As a result, any food in your intestines will quickly travel to your bowels and create a sense of urgency for the bathroom. This is just another reason why staying properly hydrated is so incredibly important during running. [Find out how to tell if you’re properly hydrated here–#10].

Give your body time to acclimate. Just like your legs and lungs have to build endurance, your stomach and intestines have to acclimate to running. Going from couch to 5K will definitely lead to an upset stomach. Train your stomach to handle the up and down motion of running by gradually increasing intensity, distance and speed. And if you’re new to running, don’t try to drink a sports drink right away. The sugar in a sports drink helps with fluid uptake and to replace lost carbohydrates, but it can cause some GI issues. If you’re increasing your mileage and want to try a sports drink, dilute it with water at first and gradually move to more concentrated versions.

Don’t try something new on race day. Many times, runners only use gus and gels on race day. That’s a surefire way to upset your stomach. If you run for more than an hour, you should supplement your run with a sports drink, gel or gu. Try these supplements during your training runs to give your body time to adjust. These products are meant to provide fuel quickly, so they quickly digested and may cause severe indigestion.

Don’t eat a large meal before a run. Remember how I said that the blood goes to your muscles and away from your stomach during a run? Well, a large meal can take 2-3 hours to digest. If it’s sitting in your stomach, it’s bound to cause some discomfort. If you feel like you need some pre-run fuel, opt for simple carbohydrates, like a piece of fruit, a swig of homemade sports drink, or a slice of toast.

Steer clear of sugar alcohols and high fat foods. Sugar alcohols found in sugar-free items have been known to cause stomach issues, like loose stool or diarrhea. You may not realize you’re eating them, so make sure you read the ingredients and look for things that end in -ol. High fat foods also take a long time to digest and can cause indigestion. Avoid fatty meals containing fried foods and fatty meats before a run.

Be mindful of coffee and tea intake. I’m a big supporter of caffeine at least 2 hours before a race, but caffeine affects everyone differently. If coffee or tea make you feel like you need to use the bathroom, don’t have it right before a run. And you may want to think of avoiding it on race day.

If you want more insider tips about fueling for running, make sure you sign up to receive info about The No-Brainer Nutrition Guide For Ever Running. It’s coming soon, and it’s packed full of amazing RD-approved sports nutrition info. And as an added bonus, I’ll also send you a FREE copy of my Race Day Nutrition Pocket Guide!


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  • Reply
    March 5, 2016 at 11:29 am

    Great post! Keep it up:)

  • Reply
    November 16, 2018 at 6:32 pm

    As someone with IBS, I’ve absolutely had more than my share of stomach issues when running. Thanks for such a helpful article!

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