By Ethan BrooksUpdated November 2026
Yes, energy gels can make you poop, and for some runners they do it fast. The concentrated carbohydrates in a gel pull water into your intestines and speed up gut transit, so the urge can show up mid-run. Most of the time, the effect comes down to how much you take, how quickly you take it, and how much water goes with it.
Why Energy Gels Affect Your Bowels
A typical gel is a dense mix of simple sugars, often maltodextrin and fructose, packed into a few ounces. Your small intestine can only absorb so much carbohydrate per hour. When intake outpaces that limit, the excess sugar stays in the gut, draws water in by osmosis, and gets fermented by bacteria. The result is cramping, bloating, gas, and a sudden need for a bathroom.
Shopping for one? See our guide: Honey Stinger Energy Gels Review (2026): Pros and Cons.
Running adds to the problem. Jostling motion, reduced blood flow to the gut during hard efforts, and the body’s stress response can all speed up motility. A gel that sits fine during a slow training run can cause trouble at race pace.
Factors That Make It Worse
Several variables determine whether a gel sends you to the porta-potty:
- Fructose load. Gels with high fructose can overwhelm absorption, especially when combined with glucose in large amounts.
- Intake rate. Taking two or three gels in quick succession, rather than spacing them out, concentrates the sugar load.
- Water intake. Gels need fluid to move through the gut. Taking them dry or with very little water can slow digestion and increase cramping.
- Your gut history. Runners who already have sensitive stomachs, or who react to lactose, sugar alcohols, or artificial sweeteners, are more likely to react.
- Training status. Gut tolerance improves with practice. Runners who only use gels on race day often have more problems than those who train with them.
If you have frequent diarrhea, blood in your stool, or persistent abdominal pain, see a doctor rather than trying to fix it with fueling changes alone.
How to Keep Gels From Upsetting Your Gut
- Start with half a gel during your long runs and build up to a full serving over several weeks.
- Take gels with 4 to 8 ounces of water, not dry.
- Space gels every 30 to 45 minutes rather than stacking them.
- Test the exact brand and flavor you plan to race with. Flavors and formulas differ.
- Check labels for sugar alcohols or large fructose doses if you have a known sensitivity.
- Avoid high-fiber or high-fat meals in the two or three hours before a long run or race.
For more on dosing and timing, see When to Take Energy Gels: A Marathoner's Timing Guide. If you already know gels are the problem, Why Do Energy Gels Give Me Diarrhea? Causes and Fixes covers the specific causes in more depth. Runners curious about what drives the formula itself can read Why Is There Maltodextrin in Energy Gels? Purpose and Trade-Offs.
What We’d Use
If you need a gentler option to test, a lower-fructose gel built around maltodextrin is a common starting point for sensitive stomachs. Pair any gel with a dedicated handheld bottle so you can take water with it on the move.
FAQ
Why do gels make me poop during a race but not in training?
Race pace, nerves, and a larger total carb intake all increase gut stress. Practice your full race-day fueling plan on long runs to see how your body responds.
Can I stop gels from causing diarrhea?
Often yes. Lower the dose, take each gel with water, and space them out. Gradual training helps your gut adapt over time.
Should I stop using gels if they upset my stomach?
Not necessarily. Try a different brand or a chewable carb option first. If problems continue, talk with a sports dietitian or your doctor about a personalized plan.
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About Ethan Brooks
Ethan Brooks is part of our editorial team and reviews and edits our marathon & half-marathon guides, checking product details against manufacturer specifications and owner feedback.
