IBS Tracker Food Diary: Fennel

iPhone app by Kamal Nasir

IBS food diary and symptom tracker for iPhone: Fennel logs meals, symptoms and stool, then shows how often symptoms followed each food and FODMAP group.

What it does

• Log a meal in seconds, a symptom in three taps and stool in two, on screens with large targets, nothing moving and a haptic when an entry saves
• Compares the days you ate a food against the days you did not, inside fixed time windows, and reports how often symptoms followed, by single food and by FODMAP group
• Every reading opens onto the days behind it: each meal, the gap before the symptom that followed, and the counts on both sides
• Reports nothing until there is enough data, and tells you how much further it has to go, for example two more days with a food
• A guided reintroduction program that schedules challenge days and rest days, records what happened on each, and drafts a reading you can accept or overrule
• A report for your appointment with your patterns, your stool record and anything you flagged, plus CSV export of everything you have logged
• No account, no sign in, no server, no analytics and no advertising, with a Face ID lock; the diary stays on the phone you logged it on

Fennel is a diary and a statistics tool. It does not diagnose, treat or advise, and it is not a substitute for your doctor or a registered dietitian.

Questions people ask

How can I find which foods my IBS symptoms follow?

A food and symptom diary gives you a record to look at and to discuss with a doctor or registered dietitian. Fennel compares the days you ate each food with the days you did not and reports how often symptoms followed, by food and by FODMAP group, and every reading shows the days and counts behind it.

Is there an app for FODMAP reintroduction?

Fennel has a guided reintroduction program. It schedules challenge days and rest days, records what happened on each, and drafts a reading you can accept or overrule. Phase lengths appear as ranges because its sources state them as ranges, and each source is one tap away. The program is part of Fennel Pro.

Does Fennel tell me which foods to avoid?

No. Fennel never labels a food good or bad and never tells you to avoid anything. It reports how often symptoms followed a food or a FODMAP group, colour marks only how strong the evidence is, and what to do about a pattern is for you and your clinician to decide.

Comparing apps? See the guide: Best IBS tracker and food diary apps for iPhone in 2026.

More apps by Kamal Nasir

• Kamera Pro: LiDAR Night Vision
• Nocturne: Card Value Scanner
• HydroNest Family Water Tracker
• Halo: Migraine Tracker
• Litmus Label Reader
• Halal Scanner - Dalil
• ChartKey: Medical Keyboard
• Therapy Notes Keyboard NoteKey
• BPM, Key and Loudness: Quint
• Drone Weather Hourly: Pitot
• Jolt: Tic Tac Toe

Published by Kamal Nasir, the developer of the apps marked Ours. Apps change, so check each one's App Store page for its latest features.