While stomach cramping can happen any time during your workout, you’re more likely to experience gastrointestinal (GI) discomfort, or gut rot, when you’re dehydrated in fluids (specifically water) and electrolyte stores, with necessary electrolytes and nutrients including sodium, potassium, calcium, and magnesium.
You might also get gut rot if you ate too close to a training session, giving your body inadequate time to fully digest your pre-workout snack and keep your stomach at ease. And if you do eat too close to a training session, you're effectively creating an internal competition for proper blood circulation.
“If you eat too much before exercise, your GI system is competing for blood with your legs, which need it for strength and energy support,” Lauren Harris-Pincus, MS, RDN, and the author of The Everything Easy Pre-Diabetes Cookbook, says. "So, your stomach loses out and digestion slows down."
This is especially important for workouts with high-intensity and plyometric work where you jump off of the ground, as with squat jumps, high knees, HIIT, and sprinting. Here, you’ll need to be extra vigilant with nutritional habits.
What’s more, the quality of your fuel also matters. If your pre-workout snack doesn’t agree with you and just sits undigested, it can create gas, bloating, and — subsequently — gut rot and other mid-workout GI pain. Exercise stimulates the bowels and food particles can churn inside of your stomach as you move, so any food excess can also weigh you down and create lethargy, too.
“Eating too much volume or a food that is slow to digest anyway, like high-fiber or fatty foods or meat, can cause some distress,” Harris-Pincus says.
Tips for Pre-Workout Fueling to Avoid Stomach Pain
“To avoid dehydration, you want to drink about 16 ounces of water two hours before exercise, and unless you are exercising more than 60 minutes in hot and humid conditions, water is fine,” Harris-Pincus says.
If you’re going for longer, use an electrolyte-filled sports aid or tablet before your workout, in addition to drinking plain water.
In general, save new foods and snacks for when you’re not getting ready to train later, since your body doesn’t know its tolerance to the food's elements, and there’s a greater risk of experiencing GI distress afterward.
“Stay away from new foods or things that feel heavy or difficult to digest,” Harris-Pincus explains.
Being adventurous with your palate and keeping a nice variety in food choice is great, but it's best to make sure you’ve tested new foods (and deemed them safe and easy on your digestive system) beforehand. That way, you can feel confident eating and integrating them into your snacks and workout fuel.
Examples of food sources that might feel uncomfortably heavy include thick soups, beans and legumes (which cause gas), high-fiber and dense grains or puddings, and meats such as beef stew and steak.
The Best Foods to Eat to Avoid Mid-Workout Stomach Cramps
“A pre-workout snack or meal should be low in fat and fiber, should contain a moderate amount of carbs and protein, and should be adequate in fluids,” Harris-Pincus says.
Water and pre-workout sports drinks (as long as they’re low in sugar and calories) are the best liquid alternatives, or you can simply take hydration tablets or energy capsules in the morning for an increased fuel supply that’ll last 4-6 hours and help you power through your workout.
Food-wise, there are a few solid options that have fast-acting carbohydrates and a bit of fiber, but are more refined and easily digestible by nature, such as oats and grains, dried fruit, and low-sugar trail mixes (instead of beans, Brussels sprouts, or chili, for reference).
Whole grains and oats are helpful, rather than starchy carbohydrates, like chickpeas or lentils.
“During a workout, muscles use their glycogen stores as a source of fuel, so carbohydrates from whole grain sources are an excellent way to give your body these easy-to-digest carbohydrates while preventing mid-workout cramps,” Trista Best, MPH, RD, LD, says.
However, you should integrate oatmeal into your pre-workout meal plan slowly so that your gut has time to adjust to the fiber.
“The soluble fiber in oats draws water into the intestines and slows down digestion, which can help prevent a mid-workout bowel movement as well,” Best adds.
There’s one top food to keep at home as a pre-workout staple, though. And it just so happens to complement oats and grains, too.
The No. 1 Best Pre-Workout Food for Avoiding Gut Rot
The best pre-workout fuel when you want to avoid dealing with gut rot is a banana.
“Bananas are a good choice because they are easy to digest, and there's a slow enough absorption of the sugar in them to fuel a workout,” Harris-Pincus says.
Plus, they have electrolytes, which increase the body’s supply for use during exercise and post-workout recovery.
“They are rich in carbs and potassium — an important electrolyte to help reduce the potential for cramping — and are practical because they’re portable and don't need refrigeration for when you’re on the go,” Harris-Pincus says.
How Much Volume Should Your Pre-Workout Fuel Have?
The size of your pre-workout snack depends on how close you are to exercising and how well you tolerate eating before a workout in general. It's crucial to consider how long you’re exercising for, too.
“If you have 2-4 hours until exercise, it should be a larger snack, such as a whole banana, a serving of carbs from cereal, bread or oats, and some protein, like an egg or peanut butter, along with water,” Harris-Pincus says.
If it’s only a 30-minute window and your workout is under an hour, halve the banana and see if it’s sufficient. The key is finding a balance between fueling your workout properly and not causing GI pain, so using trial and error to figure out what works best for your individual needs is often necessary at first.
Easy Snack Ideas to Avoid Cramping and Pain
A small stack of protein pancakes made with oat flour, mashed banana, and egg provides a perfect example of getting in easily-digestible fuel before a workout.
“This will provide some protein with longer-acting whole grain carbs and quick-acting carbs in the banana,” Harris-Pincus says.
Another option is a small bowl of cereal with protein-rich fortified milk (which also includes calcium and vitamin D) and a sliced banana.
And if neither of those options is up to par with your taste buds, Harris-Pincus recommends a peanut butter sandwich. A mini-sized sandwich blending peanut butter and banana on toast is simple and nutritious. Plus, it has a small dose of easy-to-digest plant protein and healthy fat, along with fast-acting and muscle-fueling carbohydrates for energy and adequate recovery.