Running with IBS or Bloating: Strategies for Comfort and Performance

You've adjusted your pre-run meals. You've practiced fueling during long runs. You're staying hydrated.

But what if you're still dealing with bloating, cramping, urgency, constipation, diarrhea, or an unpredictable stomach?

While occasional digestive discomfort is common among runners, persistent symptoms may signal that something more is going on.

The good news is that many runners with IBS, food sensitivities, or chronic digestive symptoms can continue to train, race, and enjoy running. The key is finding strategies that support both gut health and adequate fueling.

Chronic digestive symptoms could be a sign of something more like IBS, reflux, food intolerances, IBD and pelvic floor dysfunction.

When Is It More Than "Runner's Gut"?

Many runners assume digestive symptoms are simply part of the sport.

Sometimes that's true. But if symptoms occur regularly outside of exercise, it's worth taking a closer look.

Common signs that something more may be contributing include:

• Frequent bloating

• Ongoing constipation

• Recurrent diarrhea

• Abdominal pain

• Excessive gas or belching

• Symptoms that occur on both running and non-running days

• Difficulty identifying a clear trigger

Conditions such as IBS, reflux, food intolerances, celiac disease, inflammatory bowel disease, pelvic floor dysfunction, or other gastrointestinal conditions can affect runners.

If symptoms are persistent or severe, discussing them with a healthcare provider is important.

IBS and Running

One of the most common digestive conditions among runners is Irritable Bowel Syndrome (IBS).

People with IBS may experience:

• Diarrhea

• Constipation

• Mixed bowel habits

• Bloating

• Cramping

• Urgency

Exercise itself does not cause IBS, but running can sometimes amplify symptoms that are already present.

For example, a runner who already experiences urgency may find that the movement and intensity of running make symptoms more noticeable during training.

Before You Eliminate Foods, Look at the Big Picture

Many runners respond to digestive symptoms by removing foods.

Gluten. Dairy. Beans. Fruit. Carbohydrates.

CAUTION: Extensive restriction can create new problems:

• Inadequate energy intake

• Poor recovery

• Increased food anxiety

• Reduced enjoyment of eating

• Limited variety in the diet

• Relative Energy Deficiency in Sport (REDs)

As both a sports dietitian and digestive health dietitian, I often encourage runners to investigate symptoms thoughtfully rather than immediately assuming a food needs to be eliminated forever.

Sometimes the issue is the food. Sometimes it's the portion. Sometimes it's the timing. And sometimes the issue has nothing to do with food at all.

Fiber Timing Matters

Fiber is important for digestive health, heart health, and overall well-being.

But timing can matter for runners with sensitive stomachs.

Many runners notice fewer symptoms when they save higher-fiber foods for meals that are several hours away from a workout.

For example:

Instead of:

• Large bowl of bran cereal before a long run

You might try:

• Bagel with peanut butter

• Oatmeal

• Toast and eggs

Then enjoy higher-fiber foods later in the day when you're not preparing to exercise.

The goal isn't to avoid fiber—it's to find timing that works for your body.

Lactose and wheat are a examples of some fermentable carbohydrates that can cause digestive symptoms in some folks

What About FODMAPs?

Some runners with IBS notice symptoms after eating foods high in fermentable carbohydrates, often called FODMAPs.

Examples include:

• Garlic

• Onion

• Certain dairy products

• Wheat products

• Apples

• Pears

• Certain sweeteners

For individuals with IBS, a short-term low-FODMAP approach guided by a registered dietitian can sometimes help identify triggers.

However, the goal is not long-term restriction.

Many FODMAP-containing foods provide important nutrients, fiber, and enjoyment. The reintroduction phase is often the most important part of the process because it helps identify what your body tolerates and in what amounts.

Stress and the Gut Connection

Running can be physical, but digestive symptoms are not always purely physical.

The gut and brain are constantly communicating.

Stress, anxiety, poor sleep, travel, race-day nerves, and major life events can all influence digestive symptoms.

Many runners notice:

• Increased urgency before races

• More bloating during stressful periods

• Greater symptom severity when sleep is poor

If symptoms seem unpredictable, consider looking beyond food alone.

Factors such as recovery, sleep, training load, and stress management may be part of the picture.

Constipation in Runners

While runner's diarrhea gets most of the attention, constipation is also common.

Potential contributors include:

• Inadequate hydration

• Low carbohydrate intake

• Low overall food intake

• Insufficient fiber

• Travel

• Changes in routine, sleep, stress

Many runners are surprised to learn that chronic underfueling can contribute to constipation. Your digestive system functions best when it receives adequate energy and nourishment.

If you're constantly trying to "eat clean," avoid carbohydrates, or maintain a calorie deficit while training, your gut may not be getting the support it needs.

One of the biggest mistakes runners with digestive concerns make is avoiding fuel during training.

Fueling Still Matters

One of the biggest mistakes runners with digestive concerns make is avoiding fuel during training.

While it may seem logical to eat less in hopes of preventing symptoms, underfueling often worsens performance and can sometimes increase GI distress.

Instead of eliminating fuel entirely, consider:

• Practicing fueling during training (aka “gut training”)

• Experimenting with different carbohydrate sources

• Testing portion sizes

• Adjusting timing

• Building confidence in your fueling plan

Many runners discover they tolerate more than they initially thought.

When to Work with a Dietitian

Consider seeking support if:

• Symptoms interfere with training

• You feel anxious about eating before runs

• You've eliminated multiple foods 

• You're struggling to fuel adequately

• You're unsure whether symptoms are related to IBS, food intolerances, or exercise

A sports dietitian with digestive health experience can help identify patterns while ensuring you're still meeting your energy and nutrient needs.

The Bottom Line

You don't need a perfect gut to be a runner.

Many runners successfully train and race while managing IBS, bloating, constipation, food sensitivities, and other digestive challenges. The goal isn't to eliminate every symptom or create a perfect diet. The goal is to understand your body's patterns, fuel adequately, and find strategies that support both comfort and performance.

With curiosity, patience, and a willingness to experiment, it's possible to build a fueling approach that helps you feel confident on the starting line and comfortable throughout your run.