Food diary for bloating: a free printable, and how to read it

A food and symptom diary is a log of what you eat, when, and how your gut feels afterward. Keep it for about two weeks, write things down as they happen, then read it for foods that line up with your bloating more often than not. The diary gives you suspects. A test tells you which of them, if any, is doing it.

Download the free printable (PDF): A4 or US Letter

Why it's worth keeping one

If you get bloated a lot, you probably already have a theory about which food does it. There's a good reason to write it down: hunches about food are often wrong. In one population study, 20% of people reported a food intolerance. Tests where people didn't know which food they were eating put the estimated population share reacting to the eight foods tested at fewer than 2% (Young et al. 1994).

What to write down

The printable fits a week on one page: a row per day, a box for each meal, and an hour strip where you mark when you ate and shade when you felt it.

How long to keep it

Two weeks catches two weekends and a few repeats of your usual meals. Nobody has tested which length works best, and advice ranges from 3 days to 5 weeks, so two weeks is a rule of thumb.

Keep it light

Write things down as they happen. In a study of people keeping paper symptom diaries, they said they'd filled in 90% of their entries on time. Hidden tracking showed it was 11% (Stone et al. 2002). A quick phone note at the table beats a neat page filled in on Sunday night.

You don't need to weigh food or count anything. "Pasta with garlic, big plate" is enough. And if logging starts to make you anxious about eating, log less or stop.

How to read it, with a worked example

Here are four days from a sample diary:

Go through it in this order.

1. Mark the bad stretches. Monday afternoon, Tuesday night into Wednesday morning, and a mild patch on Wednesday.

2. Look back further than the last meal. Your gut doesn't keep office hours. Some symptoms start within a couple of hours of eating, and some show up the next day. Wednesday morning's bloating sits closer to Tuesday's garlic and onion dinner than to anything eaten on Wednesday.

3. Check the comfortable days. It's the easiest step to skip. Thursday's pasta without onion went fine, so the pasta itself looks less likely than the onion and garlic. Lentils are harder to read: Monday's soup came before an afternoon of bloating, and Tuesday's small bowl came before a bad night, but that night also had garlic and onion at dinner. A food that turns up before bloating but also sits well on other days is a weaker suspect.

4. Look at portions. Compare how you feel after half a bowl of lentils and a full bowl. A few moderate portions in one meal add up.

5. Note the rough nights and hard days. Stress and gut symptoms tend to rise together. Wednesday's mild bloating followed five hours of sleep and a rice salad. Keep noting sleep alongside meals and look for repeats.

From this week, the candidates to test are lentils, and garlic and onion at dinner. One bad afternoon is a clue. If the same food keeps lining up with symptoms, and you're fine on the days you skip it, test it.

When no pattern shows up

Some food effects are too small or too slow to see by eye.

If two weeks show nothing, you've got three reasonable next steps:

• Test a common suspect anyway, like a big serving of onion, garlic, beans or wheat.
• Look at the day lines: late eating, short sleep, stressful days.
• Stop logging for a while. You can pick the diary up again when you want it.

From a pattern to a test

A diary shows what lines up. To test whether a food affects your bloating, change one thing and watch. Cut one candidate for about two weeks, keep everything else the same, and keep logging. Then bring it back and see whether the bloating returns. Diet guidelines say to keep any cut-out phase to "no more than 4-6 weeks" before you reintroduce (Chey et al. 2022), and every food you cut should come back for a retest.

Testing also catches the wrong suspect. In a blinded study of people who believed gluten bloated them, fructans, fibers found in wheat, onion and garlic, raised their bloating scores. The researchers found no difference in symptoms between gluten and the comparison bars containing neither gluten nor fructans (Skodje et al. 2018).

Some home food-intolerance tests measure IgG, proteins your body's defense system makes when it encounters food. A European allergy task force advises against using IgG tests to find food intolerances (Stapel et al. 2008).

Skip the paper

Gut Twin is a diary that runs the test for you. You pick meals from a food list, log how your gut feels and your poop, and run one small test at a time against your own days. Each test ends with one of four results: helped, no change, worse or unclear. Every suspect is a best guess until a test backs it up. The printable works fine without it.

What we don't know yet

Nobody has worked out the best length for a food diary, or how many repeats it takes before a pattern is real. Two weeks is a rule of thumb, and so is "keeps lining up" in the example above.