How to Keep a Food and Symptom Diary

A food and symptom diary is the part of this process that does the actual work. The screen gives you a shortlist to start from; the diary is what turns that shortlist into something you can trust or discard. This page covers what to record, how long to record it for, how to spot reactions that arrive hours or days after the food, the mistakes that quietly ruin most diaries, and how to run a structured reintroduction at the end so your conclusions mean something.

It is written to be usable on paper. You do not need an app, a subscription or a lab. You need about four minutes a day and the discipline to write things down when they happen rather than reconstructing them at bedtime.

What this screen is — and what it is not

Before the practical part, it is worth being blunt about where the report fits, because it changes how you should treat what the diary tells you.

What the hair sample screen is:

• A non-medical intolerance screen that reports entries generated by the proprietary, non-diagnostic process across 700+ items on the £49 Gold screen (350 foods and 350 non-food items).
• A way of producing a short, specific starting list instead of guessing between hundreds of everyday ingredients.
• A structure for self-experimentation: something to remove, something to bring back, something to observe.
• A prompt that may help you spot patterns you would otherwise never have thought to look for.

What it is not:

• A diagnostic test. This style of screening has no proven accuracy, and the report on its own proves nothing about your body.
• An allergy test. It does not measure IgE antibodies. If you have ever had swelling, breathing difficulty or a sudden severe reaction to a food, that is a matter for your GP or an allergy clinic, not for a screen like this.
• A test for coeliac disease, lactose intolerance, inflammatory bowel disease or irritable bowel syndrome. None of those are screened for here, and all of them need your GP.
• Evidence in its own right. The evidence for hair and bioresonance screening is weak, and the same sample can produce different results on different occasions. Everything of value comes from what you observe during elimination and reintroduction.

That is why the diary matters more than the report. The diary is your data. The report only decides where you point the torch first.

Does this sound like you?

A diary is most useful when the picture is muddy rather than obvious. It tends to be worth the effort if:

• Your symptoms come and go, and you cannot see why some days are fine and some are not.
• You suspect food is involved but you have already cut out two or three things without a clear result.
• You feel worse in the late afternoon or evening and cannot connect it to a specific meal.
• You have been told your symptoms are “probably diet” without being told which part of your diet.
• You are about to start a six-week elimination and want to be able to tell, at the end, whether anything actually changed.
• You have a report in front of you listing items worth exploring first and no idea how to test them one at a time.

If your symptoms are severe, worsening, or accompanied by weight loss, bleeding, difficulty swallowing or persistent pain, stop here and see your GP first. A diary is not the right first step for those.

What to record

Six fields, every time. More than that and you will stop within a fortnight.

1. Time, not just date

Write the clock time of every meal, drink and snack, and the clock time of every symptom. Without times you cannot measure the gap between eating and reacting, and that gap is the single most useful number in the whole exercise.

2. The food, in ingredients rather than dish names

“Curry” is useless. “Chicken curry — takeaway, contained cream, ground almonds, garlic, chilli” is usable. Where you cannot know the ingredients, say so; an honest “unknown sauce” is better than a guess you will later treat as fact.

3. Portion size

This is the field most people skip and the one that most often explains a confusing result. A splash of milk in tea and a bowl of cereal in milk are not the same exposure. Use grams, millilitres, or plain household measures — “2 slices”, “half a mug”, “roughly a fist-sized portion”. Consistency matters more than precision.

4. Symptoms with a number

Rate each symptom 0 to 5, where 0 is absent and 5 is the worst you have known it. Numbers let you see a trend across six weeks; adjectives do not. Track no more than three or four symptoms, chosen at the start and kept the same throughout. Changing what you measure halfway through destroys the comparison.

5. The obvious confounders

One short line a day: hours slept, stress (0–5), alcohol, exercise, illness, medication or supplements taken, and — if relevant — where you are in your menstrual cycle. These explain a great many “mystery” bad days, and if you have not written them down you will end up blaming a food.

6. Bowel habit, briefly

If digestive symptoms are part of your picture, note frequency and rough consistency once a day. It takes five seconds and it is often the first thing that shifts.

A worked example

Four days from a diary kept during a baseline week. Note the times, the portions, and the confounder column.

How to read that honestly

The tempting conclusion is “wheat and dairy”. Look again. Monday and Wednesday were the two heavy-bread, heavy-dairy days and also the two large-portion lunches. Tuesday had bread at breakfast and was mostly fine, but stress was 4 and sleep was short, which muddies it further. Thursday had eggs and no bread and was the best day — but it was also the smallest lunch of the week.

Four days cannot separate wheat from portion size from stress. What the diary has given you is a reasonable hypothesis and a clear next step, not an answer. That is genuinely all a diary of this length can do, and pretending otherwise is how people end up cutting out foods for years for no reason.

Spotting delayed reactions

Reactions people describe as intolerance are frequently not immediate. Reported gaps commonly run from around thirty minutes to several hours, and sometimes into the following day. That delay is exactly why memory fails and why the diary needs times written at the moment, not at bedtime.

Work backwards, not forwards

When you get a symptom, look at everything you ate in the previous 2, 6, 12 and 24 hours and mark them as candidates. Do this every time a symptom occurs. After two weeks, count how often each food appears in those windows. Foods that show up before nearly every bad episode are worth exploring first. Foods that show up equally often before good days are almost certainly noise.

Look at the load, not the single meal

Some reactions appear to depend on total amount over a day or two rather than one exposure. If you had a splash of milk on Monday and were fine, then a milky coffee, a yoghurt and a cheese sandwich on Wednesday and were not, the useful column is portion, not presence. This is why field three matters.

Accept that some days will have no explanation

Sleep, dehydration, a virus, hormonal cycle, medication and stress all produce symptoms that look exactly like a food reaction. If you cannot explain a day, write “no clear trigger” and move on. Forcing an explanation onto every bad day is the fastest way to end up with a diet of six foods and no more information than you started with.

The mistakes that ruin diaries

• Changing several things at once. Cutting dairy, gluten and caffeine in the same week means that if you improve, you have learned nothing about which one mattered — and you have made your diet three times harder for no extra information.
• Stopping too early. Most people quit at day nine, usually on a bad day. Symptoms fluctuate; nine days is well inside the noise. Six weeks is the minimum for a fair look, and it is also what the 90-day money-back guarantee asks for.
• Recording food but not portion or time. Without those two columns you cannot test dose or delay, which are the two things most likely to be going on.
• Writing it up at the end of the day. Recall is poor and biased towards whatever you already suspect. Log it as it happens, even in three words on your phone.
• Only recording bad days. Good days are data. If you only write when you feel rough, every food you eat will look guilty.
• Deciding the answer first. If you have already concluded it is gluten, you will notice every symptom after bread and none after cheese. Write down what happened, not what it means.
• Making the diary too elaborate. A twenty-field template gets abandoned. Six fields for eight weeks beats twenty fields for eight days.

Running a focused six-week elimination

1. Keep a baseline first. One to two weeks of normal eating, recorded properly. Without a baseline you have nothing to compare the elimination to, and you will not know whether things improved or you simply had a good fortnight.
2. Choose a short list. Choose two to four entries from the report that you actually eat regularly; the report does not measure a bodily reaction or establish an intolerance. Something you eat twice a year is not worth six weeks. If the report flags forty items, you are not meant to remove forty items.
3. Remove them fully for six weeks. Read labels; the same ingredient hides under many names. Partial removal produces an unclear result, which is worse than not trying.
4. Change nothing else deliberately. Same broad diet, same exercise, no new supplements, no other trials running in parallel. One experiment at a time.
5. Keep scoring the same symptoms daily. Same 0–5 scale, same three or four symptoms as your baseline.
6. Review at the end, not throughout. Compare your average scores across the baseline fortnight with the last two weeks of the elimination. Judging week by week invites you to abandon it during a normal bad patch.

If cutting foods is making your diet narrow, stressful or socially difficult, ease off and speak to a GP or a registered dietitian. Long-term restriction has its own costs, and no screen is worth a worse diet.

Structured reintroduction

Reintroduction is the half most people skip, and it is where nearly all the information is. Removing three foods and feeling better tells you almost nothing about which one, or whether it was the food at all. Bringing them back one at a time, deliberately, is what turns a hunch into something you can act on.

1. One food at a time. No exceptions. Two at once and the result is uninterpretable.
2. Build the amount over three days. Day one, a small portion. Day two, a normal portion. Day three, a generous portion — the sort of amount you would eat on a normal day before the elimination.
3. Then remove it again and wait. Two to four clear days with the food absent, still recording. Delayed reactions land in this window, and it stops one food bleeding into the next.
4. Score, then decide. Compare the reintroduction days with the last fortnight of the elimination, using the same 0–5 scale.
5. If a reaction appears, wait for a clean baseline before the next food. Go back to feeling as you did during the elimination before you start the following item, or you will attribute the tail of one reaction to the next food.
6. If nothing happens, put the food back into your diet. There is no reason to keep avoiding something that did nothing, and a broader diet is generally the healthier outcome.
7. Repeat the ones that mattered. If a food seems to cause a reaction, test it a second time a few weeks later. Reactions that repeat are worth taking seriously. Reactions that happen once are frequently coincidence.

Budget roughly a week per food. Three foods is about three weeks of reintroduction on top of the six-week elimination, so the whole exercise runs to around two to three months including baseline. That is the honest timescale.

Common questions

How long should I keep the diary for?

One to two weeks of baseline, six weeks of elimination, then roughly a week per food during reintroduction. Around ten to twelve weeks in total. If you only have the appetite for one stretch, make it the six weeks — it is also the condition attached to the 90-day money-back guarantee, alongside keeping the diary.

Do I have to weigh everything?

No. Household measures are fine — slices, mugs, handfuls — as long as you use them the same way each time. The point is being able to compare Tuesday with Thursday, not laboratory precision.

What if I have a bad week for reasons that have nothing to do with food?

Write down what was going on — illness, poor sleep, a stressful fortnight — and keep the diary running. Do not restart. Confounded weeks are still usable if you have labelled them; they only become a problem when you have not recorded why the week was unusual.

Should I record everything, or only the foods on my report?

Everything you eat and drink. If you only record the flagged items, you will never discover the trigger that was not on the list, and the screen has no proven accuracy — the list is a starting point, not a boundary.

My symptoms improved but reintroduction showed nothing. What does that mean?

It is a common and legitimate outcome. It usually means the improvement came from something other than that specific food — smaller portions, less alcohol, more regular meals, better sleep, or simply time. That is still useful information about yourself, and it is a more honest conclusion than picking a food to blame.

Can the diary tell me whether I have coeliac disease or IBS?

No, and neither can the screen. Those are clinical assessments made by a doctor, and coeliac testing in particular requires you to still be eating gluten when you are tested — so speak to your GP before you cut it out, not after. A diary can be genuinely helpful to bring to that appointment, because it gives your GP dates, timings and frequencies instead of a vague description.

More: Food Intolerance Guides