A food and symptom diary is a daily record of everything you eat and drink, when you had it, and how you felt afterwards. Keep it for at least two weeks, write down ingredients and times rather than just meal names, and patterns you would never spot from memory start to show.
It is the simplest tool for working out food triggers, and it costs nothing. Below you will find what to record, a free template you can copy or print, and how to read your diary once it is full.
Why keep a food and symptom diary?
Food reactions are easy to misjudge. Intolerance symptoms often appear hours after eating, so the meal you blame is frequently the wrong one. They also depend on how much you had, which makes the same food seem fine one day and a problem the next.
A diary fixes both problems. It gives you:
- a baseline, so you can tell whether a change to your diet actually helped
- evidence of repeat patterns, rather than one memorable bad day
- a clear record to share with a GP, dietitian or pharmacist if you need advice
- a way to spot non-food causes, such as stress, poor sleep or eating on the go
What should you write down?
The more specific you are, the more useful your diary becomes. For every meal, snack and drink, record:
- Date and time. Write 12:40, not “lunch”.
- Everything you ate and drank. List ingredients, not just the dish: “wholemeal toast, butter, two scrambled eggs, black tea” rather than “breakfast”. Include sauces, dressings, snacks and the biscuit with your coffee.
- Roughly how much. “Two slices”, “large bowl”, “half a pint”. Portion size often explains why a food bothers you some days only.
- Brands for packaged food. Ingredients vary between brands, and you can check labels later.
For every symptom, record:
- What it was: bloating, wind, tummy pain, loose stools, headache, tiredness, itchy skin.
- When it started and how long it lasted.
- How bad it was, on a 0–10 scale, where 0 is none and 10 is the worst you can imagine.
Finally, add a few words about the day: sleep, stress, exercise, alcohol, medicines and, if relevant, where you are in your menstrual cycle. These all affect digestion.
Free food and symptom diary template
Copy this table into a notebook, spreadsheet or notes app, or print this page. The first row shows how a completed entry looks.
| Date | Time | Food and drink (all ingredients) | Amount | Symptoms | Started | Severity (0–10) | Lasted | Other notes |
|---|---|---|---|---|---|---|---|---|
| Mon 3 | 12:40 | Cheese and tomato sandwich (white bread, cheddar, butter), salt and vinegar crisps, latte | 1 sandwich, 1 small bag, 1 medium latte | Bloating, wind | 15:30 | 5 | 3 hours | Rushed lunch at desk, slept 6 hours |
At the end of each day, add one overall score for how you felt. It takes ten seconds and makes good and bad weeks easy to compare.
At the end of each week, fill in a short review:
| Symptom | Days it happened | Foods eaten in the 24 hours before | Possible pattern |
|---|---|---|---|
| Bloating | Mon, Wed, Sat | Latte, cheese, white bread | Dairy? Check portion sizes |
How long should you keep a food diary?
Aim for at least two weeks before you change anything. That is long enough to cover a range of meals and catch repeat patterns, and short enough to stick with.
If you then try an elimination diet, keep the diary going throughout. It shows whether symptoms ease while foods are removed, and whether they return when each one comes back. Our guides on how to do an elimination diet properly and the food reintroduction schedule explain how the diary fits each stage.
How do you spot patterns in your diary?
Set aside 15 minutes at the end of each week and work through these questions:
- Which symptoms came up most often? Highlight them.
- What did you eat in the 2–24 hours before each one? Intolerance symptoms usually appear a few hours after eating, sometimes longer.
- Which foods appear before symptoms three times or more? One coincidence is common; three is a pattern worth testing.
- What was different on your good days? Foods that are missing on symptom-free days are just as telling.
- Did portion size matter? A food that only causes trouble in large amounts points to a threshold, not a total ban.
- Could something else explain it? Check your notes for stress, short nights, alcohol or rushed meals.
Our food intolerance symptoms checklist can help you describe what you are noticing, and if bloating dominates your diary, see bloating after eating: common food triggers.
One thing to watch for: symptoms that start within minutes, such as swelling of the lips or face, hives or breathing difficulty, point to an allergy rather than an intolerance. Get medical help (call 999 if severe), and remember that intolerance testing is not a substitute for allergy testing. Our guide to food intolerance vs allergy explains the difference.
What mistakes make a food diary less useful?
- Filling it in later. By evening, you will have forgotten the snack at 4pm. Log as you go, or take a quick photo of each meal.
- Being vague. “Felt rough” and “pasta” tell you little. “Bloated, 6/10, from 3pm” and “wheat pasta, tomato sauce, garlic, parmesan” tell you a lot.
- Forgetting drinks. Coffee, fizzy drinks, alcohol and milky drinks are common triggers and easy to leave out.
- Changing your diet during the baseline weeks. Eat as normal at first, or you will have nothing to compare with.
- Stopping when you feel better. The diary is most useful during reintroduction, when you need to link symptoms to one food.
Where hair sample testing fits
A diary shows you when symptoms happen. If it has not pointed to an obvious suspect, a testing report can give you a shortlist of items to watch for and try removing first.
Our tests use bioresonance, a complementary approach outside mainstream medicine. The report is a wellness test, not a medical diagnosis, and it does not test for allergies, coeliac disease or lactose intolerance. It groups items into high, medium and low response, and every human test comes with an elimination plan and a printable food diary, so the two work hand in hand.
The Core Intolerance Test tests 500 food items. You post 4–5 strands of hair to our UK lab and receive your report within 3–5 working days of your sample arriving, or 48 working hours with priority.
Frequently asked questions
Is it better to use an app or paper for a food diary?
Use whichever you will actually keep up every day. Apps are handy for photos and search, while paper is quick and easy to review at a glance. Stick with one method for the whole period so your entries are easy to compare.
Do I need to weigh my food?
No. Household measures such as a slice, a handful or a large bowl are enough. What matters is noting whether a portion was smaller or bigger than usual.
What if I get symptoms every day?
Look at the severity scores rather than whether a symptom happened at all. Days that score higher often point to particular meals or amounts. If nothing stands out after two weeks, an elimination diet can help separate the foods from the background.
Should I include medicines and supplements?
Yes. Some tablets contain lactose or other fillers, and some supplements, such as iron, can upset the stomach. Writing them down helps you rule them in or out.
This guide is general wellness information, not medical advice. Our test uses bioresonance, a complementary (CAM) method; it does not diagnose allergies, coeliac disease or any medical condition. Speak to a GP if you have severe or ongoing symptoms.
