5 Signs You Might Have a Food Intolerance

And what to do about it.

By Carly Pollack
food prep cutting board

Pregnant looking belly at the end of the day. Irregular trips to the bathroom. Something’s definitely up with your body, but how exactly do you figure it out? Could it be that you have a dreaded (gasp), food intolerance?!

First, it’s important to know the difference between a food allergy and food intolerance. When you eat food you are allergic to, the immune system triggers a release of antibodies known as immunoglobulin E (IgE). These antibodies trigger a histamine release, which can cause mild to life-threatening reactions in the body. An allergic response usually happens within minutes or hours of consuming the food and can appear as hives, swelling of the tongue, airway and other parts of the body, vomiting, diarrhea and other extremely unpleasant digestive reactions.

Food intolerances, also called sensitivities, don’t involve the immune system and therefore cause less intense of a reaction.

Symptoms usually present themselves as digestive discomfort of some kind, rashes, headaches, mucus production (if so, you really have to rethink that cheese plate) and fatigue. These reactions can pop up days later, making it incredibly hard to connect your symptoms to a particular food.

modern white kitchenphoto by Kate Thompson


Bloating after a meal is a direct communication that something you ate didn’t agree with you. If you wake up with a flat stomach and by the end of the day you’ve entered your second trimester (it’s a food baby!), you can assume you are dealing with a food intolerance.


To be clear, a certain amount of gas is normal, especially when you eat a lot of cruciferous veggies (broccoli, cauliflower, Brussels sprouts, etc…). However, if you feel like you toot way more than what you would consider “normal”, a food intolerance may be the culprit.

fresh fruit for breakfastphoto by Kate Thompson

Constipation or Diarrhea

If your poop doesn’t #sparkjoy, you’re most likely eating something that needs to be eliminated. Your #2 patterns are a major predictor of your overall health. You are only as healthy as your digestive system, and constipation or loose stools is your body’s way of telling you something is certainly wrong. Constipation is defined as having less than twelve inches of bowel movement per day. That’s right, you can go (a tiny amount) every day and still be constipated. On the opposite side of the spectrum but just as troubling, chronic diarrhea can cause electrolyte imbalance, malnutrition, and dehydration.

cookbooksphoto by Teal Thomsen


Although not a digestive related symptom, headaches can be triggered by a food intolerance and can be a sign that you’re eating something your body doesn’t agree with. Many people with gluten intolerance will complain of headaches after eating foods that contain wheat, barley, and rye.

Skin Issues

Itchy skin, acne, and eczema are strongly tied to food intolerances. The skin is the largest detox organ on the body and has been studied to be strongly connected to the gastrointestinal system. Many skin sufferers have reported drastically improved symptoms by changing what they eat.

Botanics Beauty Productsphoto by Kristen Kilpatrick

To see if food is what lies at the root of your pesky symptoms, try a food elimination diet that removes the top inflammatory foods for three weeks (gluten, dairy, eggs, corn, citrus, nuts/seeds, alcohol, sugar, nightshades, caffeine, and processed foods). If this is too much of an undertaking, I find that removing gluten, dairy, and sugar for 10 days can work wonders for your health. You can then slowly try adding one food at a time back into your diet, and, as the food detective you’ve now become, figure out the culprit causing your digestive woes.

Solving gut issues on your own can be tricky, because these five symptoms, and the many others red flags for food sensitivities, can also be attributed to other non-digestive related imbalances in the body (thyroid issues for example). I always recommend you do further investigating if you suspect something isn’t right. If you don’t feel any better after three weeks of clean eating, it’s time to stop guessing and start testing. There are many different labs on the market for food intolerance testing, and not all of them are created equal. I suggest you work with a Certified Clinical Nutritionist like myself or a functional medicine doctor who can order the right tests and get you some real answers.

Carly Pollack is the founder of Nutritional Wisdom, a thriving private practice based in Austin, Texas. She is a certified Clinical Nutritionist specializing in holistic nutrition and transformational wellness. Carly has helped over 15,000 people achieve their health and happiness goals, and is also the published author of Feed Your Soul: Nutritional Wisdom to Lose Weight Permanently. Carly’s teachings empower you to shift your thought patterning, change your physical body, eliminate stress and live your best life.