The protocol runs in phases, and each one has a job. Loopa will not let you skip the parts that make the answer trustworthy, and it will not let the restrictive phase run on.
Baseline: one to two weeks
Nothing is restricted yet. You eat as you normally would and log how you feel. Loopa will not flag a single food during this phase, and that is deliberate: the whole protocol is a comparison against these weeks, and steering what you eat now would spoil the thing you are comparing against.
You need seven days with a symptom entry before the next phase opens. Not seven days elapsed, seven days logged.
At the end of it you answer five questions that produce a score out of 500. That score is yours, it is compared only with itself, and it is not a clinical measurement.
Restriction: two to six weeks, and it ends
You swap high-FODMAP foods for comparable low-FODMAP ones. Loopa checks meals for you and offers alternatives.
The end date is set the day this phase starts, and nothing moves it. Six weeks is the ceiling. Guidance is explicit that this phase should not run longer than four to six weeks (Chey WD et al., Gastroenterology, 2022 · doi:10.1053/j.gastro.2021.12.248), and there is no button in Loopa that extends it.
At the end you answer the same five questions again.
If it did not work, you stop
A drop of 50 points or more is the change this protocol looks for (Nybacka S et al., The Lancet Gastroenterology & Hepatology, 2024 · doi:10.1016/S2468-1253(24)00045-1).
If your score did not move by that much, Loopa's guidance is to stop here. It will not suggest cutting out more, and it will not offer you a longer restriction. That is the published advice, and it is also the honest reading: six weeks that changed nothing means FODMAPs are unlikely to be your answer, which is genuinely useful to know. Your logs are a good place for a conversation with a clinician to start.
Reintroduction: six to ten weeks
You keep the rest of your diet low, and test one group at a time over three days with increasing amounts. Then you wait for things to settle before the next one.
Testing two groups at once tells you nothing, because a reaction cannot be attributed to either. Loopa allows one challenge at a time for that reason.
Personalization: from then on
Everything you tolerated comes back. Only what actually provoked symptoms stays limited, and even that is worth retesting in a few months.
In a blinded study, people reacted to about two and a half of the six groups on average (Van den Houte K et al., Gastroenterology, 2024 · doi:10.1053/j.gastro.2024.02.008). Most of what you set aside is expected to come back.
See also: Running a reintroduction challenge · Your tolerance profile
