A challenge tests one group over three days, then you wait. It is the part of the protocol that produces an actual answer about you.
How one runs
You pick a group and a food that represents it. Loopa suggests an order, fructans and mannitol first, because those had the highest reaction rates in the blinded research (Van den Houte K et al., Gastroenterology, 2024 · doi:10.1053/j.gastro.2024.02.008), and you can reorder it however you like.
| Day | What you eat |
|---|---|
| 1 | A small or moderate serving |
| 2 | A larger one |
| 3 | A large or usual serving |
| After | Back to your low-FODMAP background until things settle |
Everything else stays low while you do it. The test food is the only thing from that group you should be having, which is why Loopa exempts the challenge food specifically rather than the whole group.
Log every day, whatever happens
A quiet day is a result. Loopa prompts you each morning of a challenge and once more the day after it finishes, because some groups show up late, polyols tend to appear quickly, while fructans, GOS and lactose can turn up the following day.
One bad day is not a verdict
This is the rule most worth understanding. In the blinded study, 26% of people reacted to a glucose placebo, a substance with no FODMAPs in it at all. Symptoms fluctuate, and expecting a reaction can produce one.
So Loopa reads your challenge like this:
- No reacting days → no reaction
- One reacting day, on the largest serving only → fine up to a point, and it records the serving below it
- One reacting day otherwise → mixed, and worth testing again
- Two or more reacting days → reacted
- Fewer than three entries → not enough to say, which is never read as "fine"
A day counts as a reaction when your own scores rise meaningfully above your own baseline, or when you called the day moderate or severe having been calm before. It is always measured against you, never against anybody else.
The wait between challenges
The next challenge cannot start until symptoms are back to their usual level. An exposure taken while the last one is still settling measures nothing, so Loopa holds the next one until you say you have settled.
You can stop one
Abandoning a challenge records nothing about that group. It stays untested, which is the truth.
See also: Your tolerance profile
