Photo: Pexels, Pixabay, ©

Gastrocolic Reflex, or Why You Run to the Bathroom after Eating

30 July, 2018 , ,

The digestive system is a pretty long organ, the small intestine is around 6 meters long, while the large intestine (or colon) measures around 1.5 meters. For this reason, digesting food can take anything between 12 and 48 hours from the moment you swallow it to the moment it ends up in the loo. It’s physically practically impossible for a food to go from one end to the other quicker.

So how is it possible that some foods feel like they’re going right through? I’ve got the answer for you here: the gastrocolic reflex.

Meal Plans to Relieve Abdominal Distress

A reflex?

The gastrocolic reflex is actually responsible for letting the large intestine know we’re eating and that it needs to make room for digesting new foods. For people suffering from irritable bowel syndrome (IBS), this reflex can be very strong and cause embarrassing symptoms, like urgency to defecate or diarrhea.

What’s actually happening is that the simple act of eating activates this reflex, the foods we’re eating have little or no effect on this signal. Aside from exceptions, for example a very fatty meal (such as fast food) which can trigger the reflex and cause stronger symptoms in sensitive people. If you’ve eaten FODMAP*-rich foods earlier in the day or the day before, this can also increase your symptoms. Depending on the type of FODMAP, this happens either because of increased absorption of water in the colon (causing diarrhea), or increased production of gas.


To reduce unpleasant symptoms and digest your meals better, I suggest you keep a food diary and work with a dietitian to identify the foods, or food groups, that cause problems. Given that digesting a food takes several hours, it’s vital to keep in mind the foods you ate during previous meals.

Need a helping hand? Check out our VIP Dietitian Service.

*FODMAPs are fermentable carbohydrates that are partly responsible for causing symptoms in people with irritable bowel syndrome (IBS). For more info, read this article.


The following two tabs change content below.


Jef L'Ecuyer

Jef L’Ecuyer

Registered Dietitian, RD at

Member of the Quebec College of Dietitians (OPDQ) and Dietitians of Canada,Jef graduated from McGill University in December 2014. Recently graduated and passionate about culinary arts, Jef poses a simple, effective and practical look at daily meal planning. With this in mind, she works in conjunction with the mission of SOSCuisine…

Jef L'Ecuyer

Latest posts by Jef L’Ecuyer (see all)

4 Responses to “Gastrocolic Reflex, or Why You Run to the Bathroom after Eating”

February 01, 2020at4:42 am, Irene Gunnion said:

Is there any way I can reduce the overworking (it seems) of gastro colic reflex. I’m 80 yrs old but walking constantly. Fit for my years—— however digestive issues have plagued me since the age of 50 yrs. I had then an ulcer —- plus hiatus hernia ( albeit small). I’ve tried MANY probiotics —— can’t hit the right one it seems. Enzymes although helping initially are now a hindrance. Thanks very much Irene

October 30, 2020at3:44 pm, Dipak Kumar Talukdar said:

how i can minimise my gstrocolic reflex?

Cinzia Cuneo

November 05, 2020at4:14 pm, Cinzia Cuneo said:

Hello Dipak,
As explained in the article you should keep a food diary and work with a dietitian to identify which foods, or food groups, cause your problem.

May 27, 2021at5:01 pm, Teresa brown said:

It doesn’t matter what I eat

Leave a Reply

Your email address will not be published. Required fields are marked *

This website uses cookies to give the best user experience, monitor the site performance, offer social networks features, or display advertisements. By clicking "ACCEPT", you consent to the use of cookies in accordance to our privacy policy.

Our weekly newsletter includes:

  • Recipes, tips and advice on healthy eating
  • Occasional promotions on products & services from SOSCuisine and some trusted partners
  • Occasional invitations to help scientific research by answering surveys or participating in studies
  • Your email address will never be shared without your permission and you may unsubscribe at any time.
SOSCuisine, 3470 Stanley, Suite 1605, Montreal, QC, H3A 1R9, Canada.