Is One of Your Favorite Foods Secretly Making You Sick? Here’s How to Find Out.

Do you feel sick after eating? Food sensitivity testing could help you narrow down which foods are causing trouble. A registered dietitian nutritionist weighs in.

If you often feel sick after eating (or just in general), listen up. Headaches, nausea, bloating, gas, fatigue, sinus problems, joint pain and skin issues are all symptoms of food sensitivity. And many of us likely have sensitivities that we don’t even know about.

Fortunately, there are many ways to learn about which foods your body may be reactive to. From elimination diets to at-home food sensitivity testing, here are my top recommendations for identifying the foods that make you sick.

Is gluten one of your triggers? Try our 7-day gluten-free meal plan.

The Low FODMAP Diet

One way to start narrowing down which foods you’re sensitive to is by following a low FODMAP diet. (Learn all about the low FODMAP diet here). FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols—which are the carbohydrates most commonly associated with stomach upset. The low FODMAP diet is an elimination diet that can help you pigeonhole which group of FODMAP foods are causing your symptoms.

Find 35 low FODMAP recipes here.

EverlyWell Food Sensitivity Testing

If you’re looking for more specific information, EverlyWell is a company that provides at-home food sensitivity testing, allowing you to see how reactive your body is to 96 different foods. The testing system measures your body’s immune response to different foods by tracking antibodies—also known as immune system proteins—from a blood sample.

Keep in mind that food sensitivity is different from a life-threatening food allergy in that it’s caused by a different antibody. That means the body’s response is delayed, so it can be hard to pinpoint exactly which food causes a reaction. For example, if you eat a meal of cashews, rice and mixed veggies, you wouldn’t know that the cashews are what’s causing you to feel sick when the symptoms pop up hours later. EveryWell’s test results can help you initiate an elimination diet based on the foods they identify you’re most sensitive to.

If you’re cutting out milk, try these delicious dairy-free foods.

LEAP Therapy

The LEAP (Lifestyle Eating and Performance) diet is an individualized eating plan that is considered the gold standard for food sensitivity testing. This therapy program has been around for decades and helped bring the idea of immune-related food sensitivities to the mainstream. LEAP testing works similarly to EverlyWell, but tests 170 foods and also tells you which foods your body is least sensitive to. This feature helps you focus on the foods that your body prefers.

Do these programs work?

Most of the testing systems will give you tiered results based on reactivity. For example, red may mean the most reactive, yellow moderately reactive and green is the least reactive. Many programs will have you eat only “green” foods for at least two weeks—and most people feel relief with this change.

Then, you start adding one yellow food per week back to your diet until you’ve tried them all. If you find a yellow food that makes you feel sick, then you know to stay away from it indefinitely. Many programs recommend not adding back your red foods, and some programs also require you to cut out any foods that aren’t tested. In the long run, these diets can be very restrictive and hard to follow depending on the number of sensitivities you have.

Even though these programs can be a good starting point, it’s important that you also get support. A registered dietitian can help you figure out which foods to cut out first, for how long and when it’s appropriate to re-introduce them.

Next: Have a food sensitivity or allergy? Here’s how to actually enjoy going out.

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Christina Manian, RDN
Christina Manian is a Registered Dietitian/Nutritionist based out of Boulder, Colorado. Hailing from Boston, Massachusetts, she has been involved with the nutrition departments of Brigham and Women's Hospital, Boston Medical Center, Dana-Farber Cancer Institute and Mass General Hospital. She completed her nutrition education at the Mayo Clinic with a focus on medical nutrition therapy and most recently practiced clinical nutrition at the University of Minnesota Medical Center. While her background has largely been in the clinical setting, Christina embraces and is shifting her focus towards wellness nutrition as the backbone to optimum health.