Hungry Runner? Subscribe to get your Hunger Scale for Runners


5 Nutrition Tips To Help with Runners Stomach and GI Distress

Do you suffer symptoms of runners stomach when running? This post will go over the main causes of gastrointestinal distress when exercising and how to help with runners gut. 

back male runner marathon runner running in forest. water bottle belt

I’ve been seeing more and more runners lately for symptoms of GI upset when running, or runners stomach. Can you relate? How many times have you been enjoying a run, only to have to stop due to cramping, nausea, gas or even reflux?

Those symptoms can be very uncomfortable and cause distress in the runners gut. For some, it happens during longer runs only, and for others, it happens whenever they fuel.

While some cases do require a more comprehensive approach (and perhaps seeing a doctor or GI specialist), many causes just require some lifestyle changes and awareness.

I talk about all of this in depth in my ebook, The Runners Guide to Intuitive Eating, and endurance course, Nail Your Nutrition: Fueling Course for Runners

If you do suffer from GI distress due to the osmolality of the gels you’re taking, or you just don’t stomach sports foods very well, here’s a link to a free download about whole foods for runners

Finally Understand How to Fuel For Running!

This is the resource you’ve been missing in your traininggrab it now!

intuitive eating ebook

Of course, take note that what works for one person will not necessarily work for another. Which is why nutrition is such an individualized science, which is the cool part. 

What is Runners Stomach

Runners stomach, or running stomach or “runners gut,” refers to discomfort or gastrointestinal distress during exercise. Feelings such as nausea, reflux, burping or stomach pain are common.

This may also explain why you get stomach cramps after running. Interestingly enough, runners are more likely than other athletes to experience runners gut.

I found one study that mentioned the frequency of gastrointestinal distress and complaints are nearly twice as high during running compared to other endurance sports, like swimming or cycling.

  • How Common Is it? GI disturbances can affect between 30-83% of runners, and as you may think, this can certainly hamper performance (1). We’ll talk about why this happens shortly. You may also suffer from stomach pain after running, which is also common. 
  • Symptoms of Running Stomach – These symptoms may manifest in the upper GI tract, with feelings of reflux or nausea. Or, you may even experience lower abdominal pain when running, or have symptoms of diarrhea.
  • How Long Does Runners Tummy Last? Generally, it’s a short term thing. Runners trots may surface during or after your workout and may hang around for a few hours. If you’ve ever had an upset stomach after running, you’ve probably experienced it. Cramping and pain is generally gone within 24 hours. 

However, the tips below should help!


Why Do We Experience Stomach Cramps While Running?

Firstly, it’s helpful to understand how our bodies work during exercise. Normally, our blood flows to the stomach, or gut, to help with digestion.

However, during a run, the brain diverts blood away from the stomach and towards the extremities and working muscles.

Therefore, things tend to just “sit” in the stomach since our body doesn’t have many resources (or manpower) being put towards them.

This can be uncomfortable for some and a major cause of gastrointestinal distress, and may also cause stomach pain when running or even a stomach ache after running. 

Hence, you may feel not hungry after workout.

Girl in blue tanktop running on beach in Block Island

Also consider that our abdominal muscles also go through a lot with the up and down motion of running, including altered motility and endocrine secretions.

There are many theories as to why we may experience runners gut symptoms and altered GI symptoms during running.

Theories for Runners Belly:

  • mechanical forces of running –> agitation of the gut
  • fluid shifts
  • decreased splanchnic blood flow
  • dehydration
  • changes in bowel transit time
  • hormone shifts
  • autoimmune changes

Here are some of the common nutrition reasons I see gastrointestinal distress in runners.

A. Dehydration

Now that we know blood flow is diverted from the gut during exercise, imagine having less blood flow period. Dehydration causes thicker blood, making it more difficult to flow.

My favorite electrolytes to help with dehydration are UCAN’s watermelon electrolytes. They quench thirst while also providing essential electrolytes. 

Ucan fueling
Click here to order

Progressive dehydration further decreases blood flow to the gut, causing even more gastrointestinal distress.

The general rule is to avoid losing over 2% of your body weight during exercise, as it can lead to a slower delivery of nutrients and oxygen to cells, altered body temperature and muscle cramping.

Dehydration can also affect performance, mental capacity and electrolyte balance.

Strenuous exercise and dehydration are the most common cause of gastrointestinal symptoms, according to a review published in the Current Opinion in Clinical Nutrition and Metabolic Care (2). 

This is a big reason I see stomach cramps after running in my clients, and why I often recommend a homemade electrolyte drink for dehydration.

B. Improper Nutrient Timing

This is especially important for a beginner runners diet.

We want to eat something before exercise that our muscles can use, however, we don’t want to eat the wrong kinds of foods.

Before a run or workout, consider sticking to refined, fast-acting carbohydrates (white bread, white rice), like many of these snacks for runners.

Not only will they be digested quickly, but they will also provide “quick energy” to use during the run.

Pre workout vs post workout nutrition recommendations vary for a reason!

Understanding healthy snacks for athletes and when to eat them is so important, even during the taper nutrition period.

bowl of oatmeal with sliced bananas

Here are some great tips on what to eat before a long run and what to eat before running in the morning.

While I’m not a huge fan of meal plans, I will say in some situations they can be helpful for retraining you how much you need to eat and some guidance on when. Marathon nutrition during a race takes lots of practice!

For example, a sample meal plan for marathon training can help someone understand portion sizes, and when to aim to include more or less of a certain macro or micronutrient around a run.

peanut butter coffee smoothie in clear glass with straws

Aim to eat larger meals 2-3 hours before a run to allow time to digest. Many runners also see success cutting out high fiber foods days before a longer run or race.

These bars are great for sensitive stomachs because they are high in carbs and superstarch and low in protein. 

If you can’t seem to figure out what foods are causing, keep a food journal and focus on reducing one high fiber food at a time before a run.

Caffeine can also cause discomfort for some runners – read more here about caffeine before running and the difference between coffee vs pre -workout before running!

cup of hot coffee in a mug

C. Improper Balance of Nutrients

Remember how blood is diverted from the gut to the working muscles during exercise? That means we typically don’t want to consume foods close to exercise that will “sit” in our stomach.

If you suffer from lower abdominal pain when running, this may be more pertinent to you.

Normally, we want to consume adequate fiber and healthy fats for our health and well-being. However, before exercise, they aren’t the best choice.

Fiber is a non-digestible carbohydrate, meaning it passes through our GI system undigested. This can result in gas production and cramping. A vegan diet for runners is typically high in fiber, so may require some modification.

Cruciferous vegetables, especially, tend to be huge promoters of gas and bloating, so I tend to tell athletes to stay away from those days before a long run or workout, or when carb loading for a marathon.

overhead shot of beans and legumes in mason jars

Similarly, fat takes a long time for our bodies to break down and may lead to feelings of sluggishness and discomfort during exercise. It’s probably best to eat these foods hours before exercise or save them for after to avoid stomach issues.

Maple water is another great option that’s not too hyper-osmolar, easy on the stomach and can be hydrating!

drink simple maple water carton in front of a pair of orange running shoes

How to Treat Runner’s Trots

If you find yourself googling “how to get rid of runners stomach,” these nutritional strategies may help ease the symptoms and help stomach cramps after running. 

1. Make a Hydration Plan

Since hydration needs may vary by person, weather and environment, and how trained someone is, it’s difficult to give precise recommendations.

This post talks a little bit more about water needs during exercise and here’s a complete guide to hydration for running.

A good rule of thumb is to consume eight ounces of fluid 15-30 minutes before a run, and 16+ ounces a few hours prior.

During a long run, drink to prevent thirst, although sometimes it can help to drink according to time. A good starting point is 0.4 to 0.8 liters per hour.

Pro tip: always keep a handheld bottle with you!

After exercise, replenishing lost water is also crucial and it doesn’t have to just be through sports drinks. Chocolate milk can be a great way to rehydrate with electrolytes, too!

Other great hydration/electrolyte options include:

glass of chocolate milk after a run

To make it more simple, to avoid dehydration, drink sufficient water before, during and after exercise. Add in adequate electrolytes during longer runs to maintain fluid balance.

Running low on electrolytes, namely salt, can also result in nausea.

If you’re a salty sweater, you may want to consider having a sweat test done with a professional and adding salt tabs in either before or during a run.

Finally Understand How to Fuel For Running!

This is the resource you’ve been missing in your traininggrab it now!

intuitive eating ebook

2. Time Your Nutrition

While it may not be possible to find a runners stomach cure, I’d bet that this one is a big one. Stick with easier-to-digest carbohydrates before exercise, like toast or a banana (more on short run nutrition) to help that running belly. 

Some people may want to stick with simple carbohydrates (white toast) vs. complex carbohydrates (whole wheat toast) because they are likely to cause less discomfort.

whole wheat toast with peanut butter, yogurt and jelly

For exercise under an hour, it’s usually not necessary to add fuel in during your run. However, when you are fueling during workouts, I always recommend practicing different products and keeping a food journal to record any adverse symptoms.

For example, you may feel better with an all-in-one powder mixed in with your water (like Tailwind or UCan), or you may prefer blocks, running chews or gels.

If you have a sensitive stomach, or feel that you are very sensitive to sugar content, Generation UCAN has a great product that utilizes superstarch (basically, a slow releasing carbohydrate) rather than quick acting sugars. 

It can really make a difference in runners belly when running.

Or, just consider foods that are easier on the stomach, like boiled salted potatoes or homemade pomegranate tart cherry gummies, may serve you better. Experiment!

Ucan fueling
Click here to order
Sunmaid raisins, Clif block chews, GU gels and hydration can all work during a run

Generally, protein and fat are unnecessary during exercise, but protein is important for post run recovery.

Most people do not spread protein throughout the day, which is one of the most important cardinal rules of protein for runners.

This is where something like a protein shake for runners could be very helpful.

Additionally, adding recovery foods, like tart cherry juice, turmeric and antioxidant-heavy foods, may help too.

This sweet potato beet smoothie is wonderful for replenishing muscle glycogen stores and adding antioxidants after a run. 

More questions about how you should fuel? Grab this resource!

3. Don’t Overdo Fat and Fiber Before Exercise

We discussed above why this is important. Fiber and fat are great for satiety, but not so great for fueling exercise.

If you’re looking for how to avoid runners trots, this is a big one. 

Perhaps the night before a long run or race, you cut down on the fiber and fat. That doesn’t mean you have to eliminate vegetables and whole grains all together.

But, some forms of fiber, like cruciferous vegetables, tend to cause more gas than others. Also, cooking vegetables (rather than eating them raw), can also make them easier to digest and prevent some gastrointestinal distress.

Veggie-rich and colorful salad, not ideal for pre-run
Avoid a high fiber salad like this before running to avoid runners cramps and GI discomfort

4. Consider Adding in Probiotic-Rich Foods and/or Supplements

Probiotics, also known as our live bacteria, may lower the incidence of GI symptoms apart from running, so it makes sense that they may also make your gut feel better during running. 

Probiotics can reduce inflammation and improve the response to oxidative damage, a by-product of running. I love this site for finding a prebiotic or probiotic specially customized for your needs. 

We do have some research demonstrating that they may improve endurance performance, as gastrointestinal health is important for regulating the adaptation to exercise.

In a 2011 double-blind, randomized controlled trial, competitive cyclists who supplemented with Lactobacillus (a popular probiotic) saw reduced severity in gastrointestinal symptoms, compared with those taking a placebo (3).

So, are probiotics the cure to your gastrointestinal distress and lower abdominal pain when running? Probably not, but they may be a piece of the puzzle!

Yogurt with fruit and granola

There do seem to be modest benefits to including probiotics for performance, but more research needs to be done. It’s worth adding some probiotic-rich foods into your diet to see if that helps with digestion and GI symptoms.

Some of my favorites are: 

5. Include Adequate Electrolytes and Energy Throughout the Run

In most instances of distance running, we do need and require fuel and carbohydrates during exercise.

Depletion of our carbohydrate and energy stores is associated with fatigue, reduced energy output (i.e performance decline), reduced skill and concentration and increased perception of effort (Source). This is why we recommend incorporating some tricks, like carb loading for runners.

I usually recommend my runners to start with 30-60 grams of carbohydrates per hour over 75 minutes. This could mean about 2-3 gels/hour, or half gel every 10 minutes, whatever works.

Taking gels at regular intervals can help your brain and body to receive a steady flow of glucose.

It’s also important to be eating enough IN GENERAL throughout the day. This marathon nutrition for race day post is helpful for so many ideas for meals!

Woman holding huma plus gel

For shorter runs and exercise under an hour, you generally don’t need to take anything for fuel. However, there are always exceptions to that.

For instance, if you suffer from hypoglycemia or are working on (re)training your gut to handle carbohydrates during exercise, then it may be a good idea to have something.

You also don’t want to wait too long to start fueling because the earlier you start, the easier it is for your gut to absorb nutrients without troubles. As you can see, it is a delicate balance.

If you are someone who suffers from gastrointestinal distress during running, it may be prudent to start practicing fueling and drinking very early in the run. Or, even practice fueling at regular intervals (i.e. – every 30 minutes) to see if it reduces symptoms or severity. 


Simons, S., Shaskan, GG (2005). Gastrointestinal problems in distance running. International Sport Medicine Journal, 6(3), 162-170.

de Oliveira, E. P., & Burini, R. C. (2009). The impact of physical exercise on the gastrointestinal tract. Current opinion in clinical nutrition and metabolic care12(5), 533–538.

West, N. P., Pyne, D. B., Cripps, A. W., Hopkins, W. G., Eskesen, D. C., Jairath, A., Christophersen, C. T., Conlon, M. A., & Fricker, P. A. (2011). Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes. Nutrition journal10, 30.

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics116(3), 501–528.

Do you have discomfort when you run? What works for you?

Join The Conversation

More For You!

Share Your Thoughts

Your email address will not be published. Required fields are marked *

  1. Hello,
    Great article :). Today i run for 7km. I just started running. It was my third treadmill run. One hour after run i started to have lowe abdominal pain. Its like cramping. Pain goes away, but then it comes back ;(. It is like that for like more then 10 hours. My stool is normal, but it is more frequent. I play play soccer 3x a week and go to the gym, but maybe my body is not custom to this type of workout. Thank you once again for the artical. Greetings from Serbia 🙂

  2. It’s amazing how nutrition can play such a big part in runner’s gut. Over the years, I’ve found that I really have to listen to my body about what it wants before/during/after a run.

    Thank you so much for sharing all your amazing nutrition knowledge in these posts Sarah!

  3. Great article, Sarah! Dehydration has been the main issue for me in training and racing, especially as I am usually nursing a baby while training. Hydrating a little extra during the entire race week has helped me immensely. It took me one majorly dehydrated race to figure that one out – that race was miserable!

  4. very informative! I’m definitely going to share this as I think there are still a lot of people out there who don’t quite know how to get it right!

  5. Pingback: February Link Love
  6. I feel pretty lucky that I don’t have stomach issues on runs. Every once in a while something will feel off but I’m glad it’s not a constant issue. It could definitely be because I know what works and never stray from it haha.

    Chocolate milk post run is the best! Love that it’s actually good for you post run since it’s chocolate haha.

  7. This is great info! In recent years, I have had issues with gels (during long runs or half/full marathons). I have found that I have to make sure to keep the plain water flowing and not over-do the Gatorade while on the race course. The Honey Stinger gels work better for me than GU, but the HS chews seem to be my best option currently.

  8. I feel like I’ve gotten a handle on my runner’s tummy…until I haven’t. Today, I had issues while running on the treadmill. Thankfully, I could take breaks as I needed. You’ve got great tips here.

    1. The treadmill is great for that, and for testing new fueling regimens. I hope it works itself out!