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12 Week Elimination Diet for IBS

When you have irritable bowel syndrome (IBS), eating can often present challenges. It would help to know if certain foods may worsen symptoms or bring about unwanted reactions. This often differs from person to person and there is no simple answer. But by taking a systematic approach you should be able to sort out which, if any food, has an effect on your symptoms.

The 4 Step, 12 Week Elimination Diet for IBS

    1. Make a list of the foods which you think may worsen your IBS. If you aren’t certain which foods bother you, start your list with fiber, chocolate, coffee, and nuts.
    2. One at a time, eliminate a food on this list from your diet for about 12 weeks to see if you notice improvement.
    3. If you do not notice improvement after 12 weeks, begin eating that food again and try eliminating the next food on your list.
    4. Begin your elimination diet with fiber.

Why This Works

There are two types of fiber – soluble which is found more in fruit and vegetables, and insoluble which is mainly derived from cereal. Insoluble fiber seems to most often cause problems. Simply removing cereal fibers (commonly found in brown bread, whole grain bread, some breakfast cereals, cereal bars, and crispbreads) from the diet may be helpful.

On the other hand, some people do find cereal fiber improves their symptoms. If so, continue it. But if it does not improve your symptoms or appears to upset you, be bold and completely exclude it for several weeks to see if your symptoms improve. Twelve weeks is a reasonable amount of time to be certain that any improvements you see are not just normal symptom fluctuations.

If there is no change after 12 weeks, there is no point in continuing, as eliminating fiber is obviously not the right approach for you. Next move on to one of the other foods to be wary of. It is important to leave them out of your diet one at a time, otherwise, you will not be able to identify which one is causing the problem.

With regard to coffee, it does not necessarily seem to be the caffeine that causes the problem, as tea can usually be continued without affecting symptoms. Caffeine-containing drinks (such as energy drinks or carbonated sodas) may cause problems, more because they are gassy rather than a result of their caffeine content. Somewhat surprisingly, spicy foods do not necessarily cause a great deal of trouble, although not everyone can tolerate them.


Dietary changes can be important in helping to control IBS symptoms, but diet is not always the answer. Sometimes simply the act of eating (smelling, tasting, or chewing food) can activate the intestines even before the food is swallowed, and the particular food being eaten does not matter. If eliminating a suspected food offender for 12 weeks does not work for you, there is little point in continuing to avoid that food. Try it with the 4 foods listed above, or any other foods you suspect.

In general, it is worth remembering that if you have to question whether a particular approach has helped your problem, it probably has not worked and should be discontinued.

IFFGD always recommends that anyone making dietary modifications to help their IBS symptoms consult with a registered GI Dietitian.  You can search for a dietitian specializing in IBS by visiting our Dietitian Listing.

Adapted from IFFGD Publication #220 by Peter J. Whorwell, MD, Professor of Medicine and Gastroenterology, University of Manchester, Manchester, United Kingdom.

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IFFGD is a nonprofit education and research organization. Our mission is to inform, assist, and support people affected by gastrointestinal disorders.

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