Most people with IBS suspect that certain foods make them feel worse. In one study, 84% linked their symptoms to at least one food.1 But memory is a poor detective. Symptoms can appear hours after eating, depend on portion size, and get tangled up with stress and sleep. A simple food and symptom diary turns guesswork into patterns you can actually see.
Why Keep an IBS Food Diary?
- IBS symptoms fluctuate from week to week, so a single bad day tells you little on its own.2
- Reactions are often delayed and dose-dependent: a small portion may be fine while a large one isn't.
- Non-food factors matter too. Disturbed sleep, for example, has been linked to worse next-day pain and gut distress in IBS.6
- It makes appointments more useful. A dietitian or doctor can do far more with two weeks of notes than with "I always feel bloated."
What to Record
- Time you ate
- What you ate and roughly how much: portion size changes the FODMAP load
- Symptoms (bloating, pain, gas, urgency) with a 0–10 severity score and the time they started
- Bowel movements, using the Bristol Stool Form Scale (type 1 = hard lumps, type 7 = watery). Doctors use this scale to classify IBS subtypes.3
- Stress level and sleep quality (a quick 1–5 rating is enough)
- Other factors: your menstrual cycle, alcohol, caffeine, new medicines
A Simple IBS Food Diary Template
| Time | Food & portion | Symptoms (0–10) | Stool type | Stress / sleep |
|---|---|---|---|---|
| 8:00 | Oats with lactose-free milk | None | 4 | Stress 2, slept well |
| 13:00 | Chicken wrap with onion | Bloating 6 at 16:00 | None | Stress 4 |
| 19:00 | Salmon, rice, green beans | Bloating 3 | 6 | None |
Copy this into a notebook or a notes app, or log meals and symptoms in the Stummy app, which keeps everything in one place.
How Long Should You Keep a Food Diary?
Aim for at least two weeks to see patterns. A diary is especially valuable during the low FODMAP elimination and reintroduction phases, where you test one FODMAP group at a time and record your response.45
How to Read Your Diary
- Look for repeats, not one-offs. A food that's followed by symptoms three times is more meaningful than a single bad day.
- Check the timing. FODMAP symptoms often appear a few hours after eating, not immediately.
- Add up the day. Several moderate sources can stack up (see FODMAP stacking).
- Check non-food columns. Bad days often line up with poor sleep or high stress.
People with more severe IBS tend to blame more foods1, and cutting out everything that ever coincided with symptoms can leave you eating very little. Use the diary to find patterns, then test suspected triggers properly (ideally with a dietitian) rather than avoiding them forever.
Once you've spotted a suspect, check it in our FODMAP checker and read our guide to the FODMAP reintroduction phase.
