How Long Should You Be on a Low FODMAP Diet?


"How long should I stay on the elimination phase of the low FODMAP diet" and "How do I know when it's time to move onto FODMAP reintroductions?" These are very common questions I hear in the FODMAP biz, though the answer may vary from person to person. Let me explain why.

The most common recommendation for the low FODMAP elimination phase is to stay on it for anywhere from 2 to 6 weeks. The reason for the range in recommended time frame is that, like with any diet, results from a low FODMAP diet will vary from person to person. There's no guarantee as to the results, although the research suggests anywhere from fifty to eighty six percent of people with IBS will have significant improvements in their symptoms on a low FODMAP diet. To each person outside of a research setting, a "significant improvement" may be defined a little differently. When I'm working individually with my clients, I like to see that they have five to seven days with minimal symptoms, or that they feel their symptoms are reduced by seventy five percent or more since starting the diet. I often give my clients a scale to fill out the severity of their symptoms upon starting together, and then we reassess this in a few weeks.

When assessing improvement with my clients, we talk about how their quality of life has improved, if they no longer need their IBS meds or may have been able to cut back on them. Some of my clients can't leave the house without Immodium when they first come to see me, so it's definitely a huge improvement when the day comes that they can confidently go outside of the house and live their lives without having to take anti-diarrheals first! Most people who were really sick before starting the diet know when they've experienced a significant improvement. For me, it was within days of starting the diet, for others it will be several weeks. Sometimes because of the learning curve of the diet, someone may not be following it quite right at first, so it may take a few weeks for them to get a handle on it. In my clinical experience, people with constipation predominant IBS can take longer to feel an improvement. Sometimes constipation can even get worse because it's very easy not to get enough fiber on a low FODMAP diet. With those clients, I'd be assessing how they've improved in terms of abdominal pain, gas and bloating.

Without having a great improvement in symptoms, if you went onto the reintroduction phase, it would be very difficult to interpret responses to challenges as some FODMAP groups will inevitably stir up symptoms. Hence why you want to wait until symptoms are stable so when you introduce a FODMAP group, if you have symptoms it will be pretty clear that it was from the group you just tested. That said, if you don't experience a benefit after 2-6 weeks on the diet, there's no evidence to support that you'll experience improvement after that time period, so there's no reason to continue on the diet. In that case, if you're working with a healthcare provider on this, do check with him/her before stopping it.

It's also interesting to observe how, as humans we can actually forget how bad we felt once, and start almost becoming hypersensitive to any mild symptom. We have to remember that some amount of gas and bloating can be a normal part of digestion. It's when it's life disrupting or embarrassing (foul smelling, frequent gas for example) that it becomes more of an issue. It's a positive thing to always want better for ourselves, but this has to be balanced with the reality that IBS is a non-curable condition, and so it may ebb and flow in severity. For example sometimes, food has little to do with a flare up. Bacterial changes, stress, and hormones are among a few of the things that can affect digestion.

For reasons I've discussed in previous blog posts it's definitely not recommended to stay low FODMAP forever. I do understand the temptation, after feeling so lousy and finally getting relief, but it's important to get through the process and figure out what your triggers are. It's actually kind of liberating too, to finally have answers!

So when you're thinking about your FODMAP journey, and wondering when it's time to reintroduce and if you're not quite sure, it may be a good idea to track how many days in a row you are going with minimal symptoms. If you feel like you're still having a lot of abdominal pain, diarrhea, and/or worsening constipation compared to when you started on the diet, it may be time to circle back around with your healthcare practitioner or to invest in working with a registered dietitian to help you problem solve and look for other solutions. Don't despair if the low FODMAP diet doesn't work for you, there's always more things you can try!