How to Avoid the “Runners Trots”

sarah cuff Food for Runners, Nutrient Timing, Running Performance, Training 3 Comments

Have you ever had to dash to the nearest washroom or porta-potty mid-run (or worse yet, mid-race)? If so, I um… I understand. Been there done that (and it’s a terrible place to be). But I know I’m not alone in having suffered these inconveniences. In working with so many runners, I see this issue show up about 20% of the time, which correlates with what research on the topic concludes.

A 1984 study published in the the Western Journal of Medicine surveyed 707 participants of the Trail’s End Marathon in Seaside, Oregon. Their results showed a high incidence of gastrointestinal disturbances – the number of runners forced to interrupt hard runs or races for bowel movements was 18% and for diarrhea was 10%. These lower gastrointestinal disturbances were found to be more frequent in women than men and in younger rather than older runners. A 1990 study published by the British Journal of Sports Medicine found that in 279 leisure-time marathon runners, 34% of them experienced gastrointestinal disturbances during or after running (20% to such an extent that is seriously affected their performance).

So what causes these issues? And most importantly, how does one prevent something like this from ever happening again?

In fact there are many different factors that could be at play. Here are five nutritional reasons one might suffer from the “runners trots” while running and strategies to overcome the same.

1. Eating the Wrong Foods before Running

If your usual breakfast is scrambled eggs (protein, fat) with cheese (protein, fat) and some spinach (fibre) and that’s what you eat before your morning run as well, chances are that you are eating an amount of protein, fat and fibre that your digestive system is still trying to breakdown as you begin to run.

Or maybe you weren’t thinking about fuelling your evening run as you chose your lunch and afternoon snack. Therefore, for example, after a large salmon fillet (protein, fat) over a huge leafy green salad with lots of veggies (fibre) with an olive oil dressing (fat) for lunch and a couple handfuls of almonds (protein, fat) as an afternoon snack, as nutritious as these choices are your digestive system is still trying to breakdown these proteins, fats and fibres as you begin your evening run.

Because running shunts the blood away from the digestive system and into the working muscles, you may end up having to make a bathroom dash. Generally, the safer foods to eat before running are high in carbohydrates and lower in the proteins, fats and fibres. Incidentally your body makes energy from carbohydrates (glucose = ATP = the energy currency for exercise), so this bodes well for energy levels as well as avoiding the ‘runners trots’.

2. Failing to Practice Nutrient Timing

Often eating too close to running may play into whether or not a runner will experience gastrointestinal distress. It is generally recommended that one eat 2 to 4 hours before running to allow for full digestion (in the amount of approximately 1 gram of carbohydrate per pound of bodyweight). Even then you’d want to reach for high carb, moderate protein, low fat and low fibre foods.

However, eating 2 to 4 hours pre-run is not always practical. While I’d encourage all runners to made a special effort to ensure they meet the 2 to 4 hour window on race day, this isn’t absolutely necessary on training days – eating 1 to 2 hours pre-run can still work. Cut the amount down by about half (eat only about 0.5 grams carb per pound of bodyweight) and keep food choices high carb and low in protein, fat and fibre.

For those who like to roll out of bed and run, the best things to reach for are a banana or a medjool date or two, or a (natural) sports drink – providing you something in the range of 15-25 grams of carbohydrate.

Practicing nutrient timing should ease the digestive distresses of even runners with the most sensitive of stomachs. Unless there’s specific food sensitivities at play…

3. A Food Sensitivity (or Two)

If you’ve already put the above two strategies into play and things still aren’t working for you, you may have a food sensitivity. I notice some people experience symptoms that they learn to live with (such as fatigue, chronic stuffy nose, heavy legs, bloated stomach, etc) – but the symptom of gastrointestinal distress while running will be what drives them to get to the bottom of the issue.

The most common food sensitivities include those to the foods wheat, gluten and dairy. Following these two foods, I’ve seen clients with food sensitivities to corn, soy, eggs, legumes, and/or very specific foods such as certain nuts (ie. cashews or almonds) or even certain vegetables (ie. carrots or onions).

Elimination of these foods will provided noticeable relief within days, and typically complete relief within weeks.

4. An Intolerance to FODMAPs 

FODMAPs are certain carbohydrates that some people are unable to absorb well, causing gastrointestinal issues such as abdominal pain, cramping, bloating, excess gas and diarrhea. This intolerance is commonly experienced by those suffering from IBS and other inflammatory bowel disorders. In runners, it may be that these foods can be eaten without problem most of the time but specifically require avoidance only before running.

FODMAPs include certain fruits (such as apples, apricots, dates, mango, papaya, nectarines, peaches and watermelon), certain vegetables (such as onions, garlic, cauliflower and snap peas), high lactose dairy (such as milk and soft cheeses), gluten (wheat, barley, rye), certain sweeteners (honey, agave, HFCS, glucose-fructose) and artificial sweeteners (such as mannitol, sorbitol, xylitol) and legumes (such as beans, lentils, soy). Click here for a FODMAP-free nutrition planning cheat sheet.

5. Consuming Wrong Type and/or Concentration of Fuel During the Run/Race

If you find the only time you experience stomach issues is in reaction to the fuel you use while you’re actually running, it could be either the ingredients in the gel and/or sports drink you’re using, or that there’s not enough water to dilute the carbohydrates being consumed.

Although maltodextrin (a glucose polymer found in many energy gels and drinks) is designed to be ideal for refuelling during exercise, I repeatedly see cases where it causes the ‘runners trots’. It should be noted that other unnecessary excess ingredients commonly found in gels such as artificial or natural flavourings, non-caloric sweeteners, and preservatives also can cause these gastrointestinal issues.

In the case of taking any gel, you’ll want to drink at least 500mL of water for every 20 grams of carbohydrate you re-fuel with in order to allow for maximum gastric emptying rate. The individuals who tend to have the ‘runners trots’ issues are those whose gastric emptying rates are too slow, thus causing ‘gut rot’, leading to ‘runners trots’.

Along those same lines if it’s a sports drink you’re consuming, you’ll want to look for one that is made in a 4% solution (4 grams of carbohydrate per 100mL water). Scratch Labs and OSMO Nutrition both take great care in ensuring their products are both made with only natural ingredients and work best for maximizing gastric emptying rate and intestinal absorption.

The above list is not exhaustive. Some people find that caffeine negatively affects their gastrointestinal system. Others find that establishing a routine (training their bodies to accept certain foods at certain times) works perfectly for them. And yet other runners realize that their GI issues only arise when they are under a lot of stress (whether it be life stress, over-training stress, nervousness stress, and/or lack of sleep stress). Or that stress simply compounds any of the above issues.

I know from personal experience (dashing into the porta-potty on a random construction site on in the middle of a training run anyone?) that suffering from the ‘runners trots’ is beyond frustrating. It led me to run on my own for a long time as it was embarrassing to encounter the issue within a group setting. For me it took eating the right foods, practicing nutrient timing, avoiding foods I realized I had a sensitivity to as well as using the right fuel during running. It took some time and effort to figure out what exactly worked for me – but as you can imagine, it’s been beyond worth it!!

To deliciously healthy food and stronger faster (trouble-free) running… Cheers,


Sarah Cuff, R.H.N.
Holistic Sports Nutritionist
Founder Eat 2 Run Sports Nutrition
CSNN Sports Nutrition Instructor
Better Bodies Club Nutritionist


Comments 3

  1. Hi Sarah
    I found that my GI problems occurred when I drank to much water while running. I tried by hydrating my self during the day (I am an evening runner) and reducing the amount of water I took during my training and that worked perfect for me, no matter what I ate before..

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  2. Pingback: Whole Grain versus Refined - Eat 2 Run

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