Why working out can make you feel bloated — and how to fix the issue

When you think of all the reasons you work out, expanding your waistline probably doesn’t top the list. But if you feel bloated after exercising you may not be imagining it. While there is little supporting research on the direct link between exercise causing bloat, there are some factors that may lead to bloat and other digestive issues that you may unknowingly do before or during exercise. This may lead you to think that wWorking out is temporarily causing bloat a frustrating side effect when you’re working hard on your fitness routine to improve your health.

Here’s a look at some of the causes that may influence post-workout bloat and the strategies to reduce and eliminate bloat to feel better during and after your workout.

Often, it comes down to what you’re doing before and even during your workouts that may cause bloat to occur, not the workout itself. Here are some of the most common reasons bloat happens during or after exercise.

Drinking fluids is an important part of exercising, but it can also be a bit of a tricky equation if you’re an endurance athlete. If you’re drinking too much water for your body to shed, sodium levels in the blood can dip. This is clinically referred to as exercise-associated hyponatremia. Among other places in the body, that water or fluid can accumulate in the gastrointestinal (GI) tract and as a result, may cause bloating.

As with many things related to health and wellness, the cause of post-workout bloat may start in the kitchen with what you’re eating before you exercise. That’s because research published in Sports Medicine states that when you exercise, blood flow is taken away from the GI tract and redirected toward the active muscles and lungs. This can halt the digestion process. If you’re doing an endurance workout, eating foods especially high in fiber, fat, and protein may cause GI symptoms.

Just like drinking too much water can cause bloat, not drinking enough water during exercise may do the same. Dehydration can be a risk factor of constipation, and when you are constipated, it’s easier to get bloated. That’s because according to Johns Hopkins Medicine, the longer stool stays in the colon, the longer bacteria have to grow, resulting in gas, bloating, and other uncomfortable GI symptoms. 

It’s important to breathe when you’re exercising in order to control your heart rate and ensure full oxygen exchange when you’re working hard. However, if you swallow too much air this can be known as aerophagia. That excess air gets stored in the stomach, which can cause bloating and gas. If you suspect this might be an issue for you, proper mouth breathing techniques, inhaling through your nose and exhaling out your mouth slowly can go a long way to prevent you from gulping air while you sweat instead.

Working out is a healthy way to reduce stress. Yet it’s important to note that high-intensity exercise can increase circulating cortisol levels in the body. Cortisol is the body’s primary stress hormone and while it’s healthy to have cortisol spikes and dips, prolonged high levels of cortisol can have a direct link to fluid retention and bloat from it. Research published in the Journal of Endocrinological Investigation found that low-intensity exercises did not have the same significant cortisol increases and could actually decrease cortisol levels.

There’s no definitive research on how long post-workout bloating may last if you’re dealing with it. What it may come down to is why the bloat is happening in the first place. For example, if you’re dehydrated, replenishing your fluid levels could relieve constipation and bloat within a few hours to a day.

If it’s what you’re eating before a workout, you may have to wait until your digestion kicks back up again after exercising to fully digest what you ate and relieve symptoms like bloat. However, you can keep tabs on your overall diet to make sure you’re consuming balanced amounts of fats and sugars which if too high, can contribute to bloat. With an at-home test like Base you’ll be able to determine your cholesterol and lipid levels and how they impact your general and metabolic health. For example, when lipid levels are too high it can increase your risk for symptoms like indigestion and with it, bloat.

If you suspect high cortisol levels are behind your post-workout bloating, knowing if you’re in a constant state of high cortisol levels can be helpful when knowing if it’s time to tune your workouts back a bit and rest or swap to low-intensity activities. Base’s cortisol test  measures cortisol levels at three different times during the day to determine exactly how your body is responding to the stress you’re putting on it. 

Once you’ve got a baseline on your nutrient and hormone levels, there are several lifestyle changes you can implement to reduce and eliminate post-workout bloat. 

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are found in things like fructose, lactose, and short-chain carbohydrates that can be difficult for some to digest. Particularly if you have a GI condition such as irritable bowel syndrome (IBS) FODMAP foods can be a trigger for gas, bloating, and other uncomfortable symptoms. That’s what makes low-FODMAP foods a vital part of a pre-workout snack, whether you deal with GI distress or not. A meta-analysis published in Nutrients determined that subjects who ate a low-FODMAP diet had less pain and bloating than those with IBS symptoms who consumed a high-FODMAP diet.

For fuel that won’t make you feel uncomfortable during or after your sweat session, snack on low-FODMAP options like bananas, berries, grapefruit, lean protein, dairy-free milk like almond milk, or a handful of nuts and/or seeds like almonds, pine nuts, and walnuts. 

Picking a water bottle might seem like an athletic version of Goldilocks and the three beverages. You don’t want one that’s too small, yet bring a big guzzler-type of jug and you risk getting bloated and feeling uncomfortable. Follow these guidelines from the American Academy of Family Physicians to stay hydrated without bloat: drink 17 to 20 ounces of water two to three hours before you exercise (with 8 of those ounces roughly 30 minutes before you lace up), 7 to 10 ounces of water every 20 minutes during exercise followed by 8 ounces 30 minutes after exercise. If you’re working out for an hour, you’ll need roughly 30 ounces of fluid to stay hydrated during and after your workout.

If you’re an endurance athlete, a sustained amount of high-intensity exercise will continue to increase cortisol in the body, keeping your levels elevated along with the likelihood of retaining water and feeling bloated. By alternating your workouts between high-intensity days and low-intensity ones, you can create a spike and dip effect with cortisol, which will ward off bloat and keep cortisol circulating through the body at a stable rate. High-intensity exercises include things like running, interval training, cycling, or any activity that leaves you breathless, unable to speak more than a few words at a time. For low-intensity exercises, try walking, swimming, light strength training, or yoga. If you suspect your cortisol levels are out of whack, you can monitor them with Base’s at-home cortisol test. By measuring cortisol levels in the morning, night, and evening, you can understand how your body responds to stressors like intense exercise and get actionable insights on how to achieve healthy levels of cortisol throughout the day.

There’s no medical research that pinpoints your workout as a reason you’re feeling bloated, yet there are some common correlations that may cause bloat around the time you exercise. For example, because your digestive system is put on pause while you exercise so that blood flow can be redirected to the muscles and lungs, bloat may be a side effect of what you’re doing before and during your workout. By monitoring your nutrient and hormone levels, staying properly hydrated, and selecting smart pre-workout snacks, it’s possible to banish post-workout bloat for good.