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Alyssa Simpson RD, CDE, CLT
Alyssa Simpson

(602) 422-9800

Sibo Doctor Approved
certified gastrointestinal nutritionist
Sibo Doctor Approved
certified gastrointestinal nutritionist

Why Do I Feel Bad Every Time I Eat? How Food Sensitivities Can Wreck Your Day

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What you eat matters If you have IBS or SIBO. Sometimes people with IBS or SIBO have such bad experiences with food that they’re scared to eat. Their symptoms range from bloating and diarrhea to extreme fatigue, hives, or joint pain. They’ve figured out that it’s probably their food causing them problems. But they don’t know why they feel bad every time they eat.

What you eat does make a difference when you have IBS or SIBO. Studies show that IBS correlates with food sensitivities. And when you can figure out and avoid the foods you’re sensitive to, your symptoms can improve.

There’s a lot of confusion out there when it comes to food reactions. If you need help sorting it out, check out this article.

If you need help figuring out which foods you’re sensitive to, check out this article.

You know you don’t react well to certain foods. But why? Why do some foods cause a reaction while others don’t? What causes food sensitivities? And what happens in your body between eating the food and having the symptom?

Let’s dig in.

What causes food sensitivities? 

Food sensitivities are non-allergic reactions that trigger the immune system. It’s common for the immune system to perceive certain foods and food chemicals as antigens or “intruders”. This causes an immune response when you eat that food. These reactions involve multiple triggering mechanisms. I’ll break it down…

Your immune system is triggered by one of the following:

  • Food antigens
  • Food chemicals
  • Immune complexes (IgG or IgM)
  • Lectins — a type of protein that binds to specific carbohydrates
  • Haptens — molecules that bind with proteins and cause an immune response
  • Amines — organic compounds that expand the capacity of blood vessels

Next, your immune system goes on alert and activates immune cells such as T-cells, lymphocytes, eosinophils, basophils, monocytes, and neutrophils.

Then it’s time for your immune system to fight. So it mounts a coordinated response to ward off invaders. It releases mediators — substances that cause your blood vessels to widen so the blood can carry immune cells to the affected area. There are about 100 different mediators that can be involved in food sensitivity reactions including cytokines, leukotrienes, histamines, amines, and prostaglandins.

Once the immune response begins, your body experiences things like:

  • Inflammation
  • Pain receptor activation
  • Smooth muscle contraction
  • Edema (swelling)
  • Excess mucus
  • Neurological reactions
  • Endocrine system reactions

When you eat an offending food (or foods) over and over again, you can develop long-term problems. Continued exposure to foods that cause an immune reaction can cause conditions like:

  • Migraines
  • Fibromyalgia
  • IBS (Irritable Bowel Syndrome)
  • Depression
  • Metabolic Syndrome
  • Asthma
  • GERD (gastroesophageal reflux disease)
  • Otitis Media (ear inflammation or infection)
  • Arthritis
  • Crohn’s Disease
  • And more…

What do these conditions have in common? 


Inflammation is your body’s response to an irritant or intruder. And it occurs when your immune system’s mediators go to work. They cause the blood vessels to dilate so more blood and immune cells can fight off the invader. 

Inflammation produces symptoms like swelling, heat, redness, pain, and even loss of function. Inflammation is not an inherently bad thing. It doesn’t feel good, but it is part of the body’s natural healing process.

If you sprain your ankle, you can see the effects of inflammation in action. But when it happens inside your body, you don’t always know what’s going on.

If inflammation occurs chronically in our bodies, these reactions can cause harm. The problems develop when inflammation is ongoing. Unfortunately, most people with food sensitivities don’t even know which foods are causing their symptoms. So they eat them again and again. And their body doesn’t get a break.

It’s now well-accepted in the medical community that inflammation can negatively affect our health in many ways. 

How do you combat food sensitivities?

The first step is figuring out which foods you’re sensitive to. Unfortunately, this is not an easy task. Unlike food allergies, sensitivities are harder to track down. Reactions are often delayed and can vary depending on the amount of the offending food you eat. 

Your best bet to pin down your sensitivities is to work with a practitioner who will run the MRT food sensitivity test. This is the test I use in my practice because it is the most accurate. Many of the food sensitivity tests on the market are unreliable at best, and fully inaccurate at worst. If you rely on false positives or negatives, you can end up doing yourself more harm than good.

If you’re interested in the MRT test, I’d be happy to talk with you. You can set up an appointment here

Once you and your practitioner have identified your sensitivities, you can radically improve how you feel by making some dietary shifts and adding in some supplements.

In my practice, I utilize an eating strategy called LEAP (Lifestyle Eating and Performance). LEAP is the most effective diet therapy I have found to rid patients of their chronic and debilitating symptoms. LEAP helps with conditions including irritable bowel syndrome (IBS), migraines, and fibromyalgia. 

LEAP is also effective in relieving symptoms of conditions that most people don’t identify with food sensitivities like:

  • Chronic sinusitis and sinus headaches
  • Functional diarrhea
  • Dyspepsia (indigestion)
  • Eczema
  • Rheumatoid arthritis
  • Arthralgia (joint stiffness)
  • Chronic fatigue syndrome
  • Autism
  • Attention deficit disorder and/or hyperactivity
  • Celiac sprue
  • Cyclic vomiting syndrome
  • Chronic urticaria (itchy skin)
  • And more… 

The LEAP program, which stands for Lifestyle Eating and Performance, is an eating plan based on your MRT results and a thorough assessment of your full clinical picture. Your personalized plan is implemented by your Certified LEAP Therapist (CLT).  A CLT is a registered dietitian (RD) — like me — with specialized training and certification in treating delayed food hypersensitivity reactions.  

This program has helped hundreds of my clients manage migraines, fibromyalgia, IBS, fatigue, body pain, and more. I love helping my patients decrease or eliminate their symptoms and get their lives back.  

Many of my patients discover that they are eating exacerbating foods every single day. Imagine the level of inflammation they’re dealing with! But when you can figure out which foods you’re sensitive to and eliminate the inflammation, you’ll see radical improvement in your overall health and quality of life! 

I know changes in diet are hard, especially when you’re eliminating foods you eat often. But I’ve seen so many clients make the changes and come alive again that I know it’s worth it.

And in my practice, I offer a high level of support to take the stress and guesswork out of planning your meals. We’ll personalize your plan so it will work with your routine and lifestyle. My goal is to make you as comfortable as possible while we’re addressing your symptoms.

When you identify your food sensitivities you:

✔ Know EXACTLY which foods you can eat, and which ones you need to avoid

✔ Can stop worrying about how you’ll feel after you eat

✔ Stop thinking about your symptoms all the time and actually live your life

✔ Regain the energy your body is expending trying to deal with exacerbating foods

If you’re ready to do the work and make the dietary changes that will help you get your life back, I can help. 

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