Your Guide to Keeping a Food Intolerance Diary
Food intolerance can sneak up in ways that disrupt daily life, from headaches to digestion issues or even low energy.
Unlike allergies, food intolerances often come with vague symptoms that make them tough to pin down. It’s frustrating when you can’t figure out what’s causing the discomfort.
That’s where a food journal comes in. Keeping a simple log of what you eat and how you feel can reveal surprising patterns over time. This practical tool puts you in control, helping you spot problem foods and take steps toward feeling your best.
I wish that I had this simple knowledge many years ago when I spent a decade not knowing why I was having rashes, bloating, and IBS symptoms.
In this article, I will unpack the benefits of keeping a food journal and how to download your own copy of a food intolerance diary and symptom log.
These are the sections covered in this article:
Understanding food intolerances
Common food intolerances & symptoms
Tracking patterns & symptoms
Difference between allergy & intolerance
What to write in a food diary
Food intolerance diary download
Analysing your entries for patterns
When to seek help
Tips for success & common pitfalls
Communicating with healthcare professionals
Understanding Food Intolerances
Many people mix up food intolerance with a food allergy, but they are not the same thing. Food intolerance happens when your body struggles to digest certain foods. This isn’t life-threatening, but it can cause a lot of discomfort. Knowing the difference helps you focus your journal and avoid unnecessary worry.
What Is Food Intolerance?
Food intolerance is essentially the body’s inability to process and digest certain ingredients comfortably. It’s the gut’s reaction to coming into contact with these foods, and as we are each bio-individual, every person has a unique reaction to ingredients.
For those who experience intolerance and sensitivity, symptoms typically build up slowly, over a long period. For some, symptoms can appear a couple of hours after eating.
Food intolerance symptoms can range from mild to severe, including abdominal bloating, headaches, and stomach pain. For some people, these symptoms exist beyond the abdomen. Many people experience brain fog, mood changes and even fatigue.
Some of the key characteristics or notable points on food intolerance include:
Non-life-threatening: Unlike allergies, food intolerance is more about discomfort rather than being life-threatening.
The symptoms come about slowly: Reactions to ingredients develop over a long period of time rather than immediately. This can make it tricky to figure out exactly what’s triggering the body.
The symptom’s strength changes based on the amount of food: A small amount of the problematic ingredient can go unnoticed, whereas a larger amount can clarify what is causing the body’s reaction.
Here's what stands out about intolerance:
Not life-threatening: Unlike allergies, intolerances are uncomfortable but rarely dangerous.
Slow symptoms: Reactions can develop over time, making it challenging to identify the trigger immediately.
Dose matters: A small amount of a problem food may go unnoticed, but a larger serving can trigger clear symptoms.
Food Intolerance vs. Food Allergy
My journey with food intolerances started in my late twenties. I didn’t realise what I was experiencing until I took a Vega Food Intolerance Test. It was this test that highlighted the 12 different foods or ingredients my body was reacting to. Later on, I discovered that I had Leaky Gut Syndrome, which was likely why I was experiencing so many food intolerance symptoms.
Part of why I am sharing this guide to keeping a Food Intolerance Diary with you is that I realised I could have saved over 15 years of struggling with IBS and skin issues, had I had proper food intolerance support early on.
Food intolerance and food allergies are often confused. Here is a simple way to spot the difference:
Food intolerance is all about the gut and digestion. When your body is reacting to foods, the symptoms are slow because they are felt as they hit the digestive system and gut.
Food allergies are a reaction of the immune system to an ingredient. Allergic reactions show up as anything from a rash to mild swelling to trouble breathing. Allergies can be life-threatening.
I like to tell people to imagine a food allergy as a fire alarm going off. Food intolerance, on the other hand, is more like a leaky tap; a slow and annoying drip that eventually wears you down over time.
How to tell if it’s a food intolerance vs an allergic reaction you’re experiencing
Keep in mind that allergies and intolerances can share symptoms. The difference is how and when these food intolerance symptoms appear. A Food and Symptom Diary PDF helps identify the difference between the two, which is important, and guides how to move forward.
So, practically speaking, you’ll need to start off comparing how your symptoms behave:
Allergic reactions appear soon after you’ve eaten, sometimes within minutes. They can include a rash, swelling, or trouble breathing.
Food intolerances, on the other hand, can take longer to appear. If you are experiencing anything uncomfortable related to your digestive system or abdomen, bloating, pain, constipation, or mind-related issues like brain fog, headaches, fatigue, or mood swings, it’s more likely to be an intolerance.
You want to write down what you ate as well as the symptoms you’re experiencing. Another key point to note down is the timing of the symptoms. Note down what time you ate your meal and what time the symptoms appeared.
This simple note-taking practice will help you figure out if what you’re experiencing is an allergy vs food intolerance and how severe it is.
Why keep a food symptom diary?
Writing down your food and drink consumption and outcomes helps to create a picture, which in turn clarifies what’s going on with your body. By tracking what goes into your body and how it responds to that consumption, you can spot patterns and triggers that you would otherwise miss.
A Food and Symptom Diary PDF turns vague feelings and assumptions into real-life data by helping you link your symptoms to meals or ingredients. It’s often foods that you wouldn’t expect! Food journaling is a simple but super helpful tool.
Tracking and symptoms
Diving deeper into your food symptom diary, it’s important to start by understanding that food reactions don’t always follow a script.
You might eat a meal and only notice a headache or upset stomach hours later. If you don’t note down what and when you’ve been eating, it is really easy to miss the links.
How to keep a food intolerance journal
Here’s how to keep a food intolerance diary:
Write down what you eat and when. This includes all food and drink. While journaling, it is helpful to make your food and meals so you know exactly what’s in them.
Record all of your symptoms. This should include anything you feel, even if it’s a small change or feeling.
Notice repeating trends and symptoms. If you find the same symptom occurring after eating a specific ingredient, it’s likely a potential culprit.
Track the timing. Note the time between eating and the appearance of symptoms, which adds more clues.
In my experience, people are often surprised by the patterns that pop up. Life is busy, and it’s easy for patterns to slip by us without us realising what’s actually going on. Something as simple as a midday snack, an after-dinner dessert, or a beverage can be the culprit.
Writing things down creates a clear timeline to examine and cuts out the guesswork from your detective work. I remember that as a treat, my sister and I would go shopping and always stop by Patisserie Valerie for a cheeky slice of cake and cuppa. My sister would notice a spot on my face that would swell up every time I ate there. Little did we know at the time that it was the dairy in my delicious treat that I was reacting to. That and I wasn’t tolerating the gluten!
Using this story, in hindsight, this is what a food journal entry would have looked like:
10 am: Cup of tea with sugar and cow’s milk.
10.15 am: Slice of cake made with wheat flour (gluten), fresh dairy cream, fresh strawberries, chocolate and eggs.
10.30: A spot appeared on my cheek and that area of my face experienced some swelling.
Tip / Note: When eating out, it’s helpful to get a full ingredient list of the ingredients in the recipe you’re enjoying. Most restaurants, especially chain restaurants, have websites with their menus that include the complete list of ingredients. If not, check with your server.
Another point I’d like to share here, as part of my food intolerance journey and learning, is that eating your food quickly and on the go or while feeling stressed can have a negative impact on your metabolism. The same goes for walking or standing while eating. All of these habits put your body into a state of stress.
Check out my Food Intolerance Diary. I designed this tool for the specific purpose of recording eating patterns for analysis. My food symptom journal includes simple, yet detailed sections where you can log your food consumption and intake as well as how you feel later on – think moods, mind and body.
My number one goal with this tool is to help you connect with your body and learn more about it through analysing the reactions its having to certain ingredients.
When to keep a food symptom diary
I’m often asked at what point keeping a food symptom diary is helpful. The simple answer is that when you suspect you have a food intolerance but aren’t sure what’s causing the symptoms, you should log your eating:
I’d recommend using a food intolerance diary if:
Your symptoms are delayed or inconsistent, making it hard to figure out what’s causing them.
You’re starting with an elimination diet and need to track multiple triggers so that you can identify a pattern.
You’re getting ready to speak with a dietician or a healthcare provider and need a detailed record.
Personally, I feel a food symptom diary helps you connect the dots over time. This gives you insight into how your body responds to certain ingredients, rather than starting from scratch with invasive tests.
Most common food intolerances and symptoms
I thought it would be helpful to list a few of the most common intolerances; here’s what to know:
Lactose intolerance: When the body doesn’t produce enough lactase, which is the enzyme needed to digest lactose, the body has a negative reaction.
Gluten intolerance: Gluten is a protein found in wheat, rye and barley. It can cause digestive issues in some people. Note that it’s a good idea to consult a healthcare provider before eliminating gluten from the diet.
Histamine intolerance: Histamine is a chemical found in certain foods like aged cheese and meats, fermented foods and some fruits and veggies. Intolerance occurs when the body reacts to trying to process histamine.
Caffeine sensitivity: Caffeine can cause unpleasant symptoms like the jitters, anxiety and headaches for some people.
Food additives: Some food additives, like benzoates and sulfites, can trigger reactions for some. These ingredients can be tricky to work out.
Other typical intolerances: Other common culprits include certain fruits and veggies like tomatoes, citrus fruits and avocados. Even chocolate and alcohol can be problematic for some folks.
Aspartame: Aspartame is an artificial sweetener that is typically used as an artificial sweetener. There is a fair amount of conflicting information out there about this ingredient – some noting effects or symptoms like depression and irritability in people sensitive to it.
Eggs: Egg food intolerance is incredibly common. Basically, some people have difficulty digesting egg whites but are not altogether allergic to them. There are different symptoms associated, such as egg intolerance, like pain in the abdomen and diarrhoea.
Food colouring: Food colourings can be problematic for some. Red 40 and yellow 5 have been known to cause hypersensitivity reactions in some individuals. Symptoms include hives, skin swelling and a stuffy nose.
Yeast: Generally speaking, yeast intolerance is experienced via mild symptoms. These symptoms are typically limited to the digestive system.
Sugar alcohols: Sugar alcohols are used a lot as zero-calorie alternatives to sugar. They can be the reason for major digestive problems in some people, including bloating and diarrhoea.
FODMAPS: These include a group of carbohydrates (sugars) that absorb poorly into the body and can cause irritation for some people.
Food intolerance symptoms can vary from person to person. The key thing is to be aware of certain symptoms. Here are ones I recommend you look out for:
Bloating and/or gas
An upset stomach or cramping
Constipation or diarrhoea
Headaches and/or migraines
Fatigue or low energy
Brain fog
Reactions in the skin, like acne/rashes/pimples/dryness/swelling
Mood changes or irritability
Nasal drip
Data for healthcare professionals
Along your journey to wellness, you’ll likely be asked by a healthcare provider (either a doctor or a dietician) about your diet. They’ll need to know what your meals and diet look like and how you feel after eating. Having a food journal makes these discussions much easier and more useful. Instead of trying to guess and forgetting details, you’ll have a record available.
Bringing along your food journal means you can provide a clear symptom history, a record of your food intake, and provide better advice. This can seriously save you time and money.
When to seek help from a healthcare provider
In a nutshell, if your journal keeps pointing to the same problematic foods or if your symptoms are getting increasingly worse; it’s time to get answers from an expert.
Contact a doctor if:
You have severe symptoms: Swelling, severe rash, trouble breathing or fainting.
Your symptoms are hindering your day-to-day activities.
Cutting out certain foods isn’t having an impact.
You aren’t sure how to test your suspicions or have questions about what is safe.
By checking your Food Journal with these steps, you’ll start connecting the dots between what you eat and how you feel.
Food Intolerance & Symptoms Diary
Below is a sample of my food intolerance diary that I created for you. A 7-day downloadable Food Intolerance, Sensitivity Diary. With the Bristol Stool Chart, 7 pages to log your food, with an additional notes page at the back. This diary is only available as a download.
Tips for success and what to avoid
Here are some quick notes for you to take in regarding success and what to avoid:
1. Be consistent and honest with yourself about your data entries.
2. Log symptoms in real time; as soon as you feel them, so you don’t miss anything.
3. Be super honest and don’t skip an entry because it was…” just a taste” at a party.
4. Use simple, clear language so you can recognise them later when you review them.
5. Avoid confirmation bias. Simply put, don’t expect yourself to be intolerant of an ingredient based on something you’ve read.
Avoiding mental traps
The way to avoid mental traps is to:
Stay open to all possibilities.
Track all foods and symptoms (obvious and not obvious).
Give equal attention to days when you feel good as the days you feel bad.
Use your Food Symptom Diary as a detective tool.
Communicating with healthcare professionals
Finally, here are a few tips on how to keep to stronger communication with your doctor or dietician so that you can get the best out of your appointments:
1. Bring along your Food Journal or send it in advance if they request it.
2. Highlight your most significant patterns and any suspicions you might have.
3. Include context: note any changes in your lifestyle like travel, stress, medication or illness.
4. Ask questions. It can be helpful to note them down ahead of the meeting.
5. Be clear about what you did and didn’t track. Highlight any missed days or notes that were maybe rushed – this just helps with interpreting data.
Conclusion
A Food Intolerance Diary or printable food diary puts the facts about your meals and symptoms into one place. This makes hidden patterns easier to spot.
By tracking your daily habits, food intolerances can reveal simple changes that bring relief from nagging problems. Start small, keep steady notes, and your body will thank you for listening.
Drop a comment below. What are your thoughts? Have you had success keeping a food journal?
Download your copy of a food intolerance diary
I am not a doctor, nutritionist, or allergist; I’m a chef. The information provided in this article is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before making any changes to your diet or addressing specific health concerns.
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