Ask Dr. Kimberley: How Do I Know If I Have Food Sensitivities?

Dr. Kimberley O'BrienAsk Dr. Kimberley, Blog, Health Leave a Comment

Hi Dr. Kimberley,
I’ve been following your blog for years and I’ve thought about doing an Elimination Diet, but I’m not really sure whether that’s the right step for me.  How do I know if I have food sensitivities? 
I live a fairly active lifestyle but still find myself feeling exhausted most days. I also experience gut cramping, bloating, diarrhea and itchy/red skin which comes and goes and almost seems totally random. Sometimes I think that I don’t do well with dairy and that it causes my digestive issues, but then I’ll eat it again not long later and everything seems to be totally fine.  Since my symptoms are so hit and miss, am I right to think they must not be caused by food sensitivities? I don’t know where to start to figure this all out, but I’m getting sick of feeling this way and having digestion issues that can totally throw off my day!
Thanks for your help!

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Hi Emily,

Thank you so much for your question! ‘How do I know if I have food sensitivities?’ is something that I get asked quite often in my naturopathic practice, so you’re not alone!  This “hit and miss” pattern is actually very common for people to notice if they are experiencing food sensitivities, although I know this makes your symptoms feel very confusing.

Fatigue is one of the most common symptoms I see in my patients experiencing food sensitivities.  However, it can definitely also be triggered by other causes, including nutrient deficiencies or hormone imbalances. I’ve created an eBook with a quiz that helps you identify the cause of your own fatigue, and you can download that eBook here for free.

In regards to your digestive and skin issues, I understand how frustrating this can be as I also used to struggle with the same concerns.  What I’ve learned personally, as well as through years of working one-on-one with patients, is that there are a number of factors that often combine to determine when and why you experience these symptoms.  

Let me explain a few reasons why this occurs, which will help you better understand what’s going on within your body!

The Symptoms Experienced due to Food Sensitivities are Both Cumulative, and Delayed

First of all, it’s important to understand that food sensitivities are caused by a delayed immune reaction.  This means that your symptoms can take up to 48-72 hours to reach a peak! Therefore, even if you experience a dairy sensitivity, you might not notice any symptoms when you first eat that piece of cheese.  However, you may wake up the next morning feeling puffy, bloated or tired.  If that next morning you then also have cream in your coffee, yogurt in your granola, lasagna for lunch and cheesecake for dessert, the immune reactivity and inflammation that you experience becomes cumulative.  

Simplified, this means that the more of a problematic food you eat, the more you start to notice symptoms.  Therefore, you may suddenly start to experience the gut cramping, diarrhea and bloating you had mentioned after eating the cheesecake, although you had eaten dairy all day while feeling “fine”. 

It’s also possible that you had that same cheesecake last week without symptoms, but that you had eaten dairy-free meals earlier on that day (ex: eggs for breakfast and a salad for lunch). Without consuming as much dairy, the immune reactivity and inflammation you experienced didn’t build up enough to cause you obvious digestive symptoms.  However, the lower levels of immune reactivity that results from occasional dairy-intake is often still enough to be dragging down your day-to-day energy!

Grilled Cheese and Coffee

You May Be Experiencing Sensitivities to More Than One Ingredient

Another possibility I see quite often in my practice, is that there may be more than one ingredient or food group that you are sensitive to.  This means that it could be a combination of two different ingredients that cause your digestive concerns, whereas individually each food is less problematic for you.  

For example, let’s say that in addition to dairy, you also have an undiscovered sensitivity to eggs.  In this case, the meals that will trigger symptoms the most for you are those with these two ingredients combined.  You may feel relatively fine having some feta cheese on your salad each day, however digging into a bowl of custard for dessert (which is loaded with dairy and eggs) or having a 3-cheese omelette for breakfast may send your digestive upset into overdrive!

Within a Specific Food Group, You May Be Reacting to Only One Type of Protein

An additional possibility that pertains most specifically to dairy, is that you may be sensitive only to cow-based dairy and not to goat or sheep dairy.  I also occasionally see patients who react only to milk protein, but not to casein. In this case, you’d experience symptoms most with foods like ice cream and milk, but less-so with aged cheeses that primarily only contain casein.

Whenever I have my patients complete an Elimination Diet to identify their food sensitivities, I always guide them to test these various dairy products (milk, yogurt, cheese) separately to help gain more clarity in this regard!

Dairy Cow

Other Factors, Like Stress, Also Play a Big Role

Outside of WHAT you’re eating, there are a lot of other factors that influence when and why you only occasionally experience digestive symptoms. 

For example, if your digestive upset tends to arise primarily at lunch, are you always eating on-the-go or in work meetings? If not, perhaps your morning coffee may be affecting how you feel.  Or maybe you’re skipping breakfast, and finding that you’re so ravenous by lunch that it makes you feel ill when you eat.

If your cramping and bloating are most often in the evenings after dinner, what is the dynamic like around your dinner table?  Are you finding the conversations or company to be a source of stress?

Stress decreases our digestive function, and this can be an additional factor as to why you notice digestive symptoms certain times more than others when consuming dairy or other foods.

How Do I Know If I Have Food Sensitivities?

Elimination Diet Meal Plan

Overall Takeaway

It can be confusing to navigate and interpret all of these symptoms on your own! If you’re still wondering ‘how do I know if I have food sensitivities?’, completing an Elimination Diet can help you to gain clarity on the root cause of your own symptoms in order to feel energized and in balance again.  An Elimination Diet enables you to identify if your symptoms are triggered by foods you’re consuming as part of your everyday diet, and personalizing your diet in this way can help to resolve your fatigue, digestive and skin concerns.

To learn more about food sensitivities and how to do an elimination diet, you can download my free eBook, “A Naturopathic Guide to Identifying your Food Sensitivities”.  I also have a comprehensive online program called the Elimination Diet Meal Plan, which walks you through identifying your own specific food sensitivities step-by-step, while enjoying absolutely delicious meals along the way! 


I’m excited to be bringing back the “Ask Dr. Kimberley” feature on the Healthy Life Redesign blog!  Do you have a question that you’d love answered in regards to health, hormones, and nutrition? Enter your question for us on our “Ask Dr. Kimberley” page, where I always do my best to answer as many questions as possible!

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Ask Dr. Kimberley: How Do I Know If I Have Food Sensitivities?

About the Author

Dr. Kimberley O'Brien


Dr. Kimberley O'Brien is a Naturopathic Doctor in  Nelson, BC with expertise in the treatment of digestive disorders, fatigue and hormone imbalances.  She is the founder of Healthy Life Redesign and creator of the Elimination Diet Meal Plan and the Real Food Recharge online programs.  Her mission is to help you own your health and live a life you love!

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