Elimination Diet: What It Is and When To Do It

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Elimination diets are a useful tool to help pinpoint specific food intolerances, sensitivities or allergies. Before you embark on an elimination diet, however, it's important to understand what exactly is a food sensitivity (the reason behind most elimination diets), and to know how you can determine when your issues are possibly the result of another condition.

What's the difference between an allergy and an intolerance?

Food Allergy

A food allergy is a physical reaction to a food caused by your immune system. When you eat the offending food, your immune system reacts; you may develop a variety of symptoms, from skin rashes to breathing problems. Some may result in what's called anaphylaxis–a life-threatening allergic reaction.

About 4 percent of adults and 5 percent of children in the U.S. have food allergies. Though only eight allergens (peanuts, tree nuts, soy, fish, shellfish, wheat, milk and eggs) account for the majority of all allergic reactions, it's possible to be allergic to practically any food.

Food Intolerance

A food sensitivity (also known as "hypersensitivity" or "intolerance") is when a person has symptoms after consuming a food that doesn't typically cause symptoms in other people. The majority of physical food reactions are due to food intolerances. These intolerances are not as well understood as allergies, as they don't involve the immune system.

It's thought that intolerances are caused by possible enzyme deficiencies (such as lactase deficiency causing a lactose intolerance). They may involve malabsorption issues within the digestive tract, or they could be adverse reactions to chemicals that occur naturally within certain foods. For instance, some people who follow a gluten-free diet may have an intolerance rather than an allergy to gluten.

Food allergies can be so severe they can occur when microscopic amounts of an allergen are present. A food intolerance reaction, however, is often dependent on how much food is consumed. The more you consume, the worse the reaction.

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What is an elimination diet? How do I do it?

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Meet with an expert.

Before starting the diet, it's highly recommended to meet with a registered dietitian or an allergist to figure out a safe plan and get medical advice. Even if you believe you know the culprit for your reactions, these experts may help identify other possible offending foods you should eliminate just to be certain you're getting the best results from your elimination diet.

A food diary is an extremely helpful tool, particularly when it comes to tracking food sensitivities. Keep a log for a few weeks, taking note of everything you eat, what time you ate it, and any reactions that take place. Paying attention to those things for a couple of weeks will help you (and your dietitian and/or doctor) identify patterns and figure out what may be causing your symptoms.

Cut the foods from your diet for two weeks.

Once you have a plan, you will eliminate all of the possibly problematic foods for two weeks, including the foods themselves and the foods as ingredients in other dishes. For example, if you're eliminating eggs, you will eliminate plain eggs as well as muffins made with eggs. This can be challenging because foods like soy and dairy are used as ingredients in lots of other food products. It's important to read labels carefully when you're at the store.

Take a self-assessment.

After two weeks without the foods, you can self-evaluate, noting if your symptoms are less severe, if you have more energy and how you feel overall. You should also return to meet with the dietitian or allergist who helped you start the process.

Start adding foods back one at a time.

It's also at this two-week point when you can start adding foods back into your diet and testing your body's reaction. It's important to add each food one at a time, leaving three days in between, in order to accurately pinpoint which food triggers symptoms.

You'll also want to consume a decent amount of each food–it's possible you'll have no reaction with only a small amount of a trigger food while eating a larger amount can cause symptoms. Begin by introducing a small amount of the food in the morning, and if you don't experience any symptoms, try eating a bigger portion of it later in the day.

Don't rush the process.

Keep in mind that reactions aren't always sudden and can happen up to 72 hours after you eat the food. If no symptoms occur within this three-day window, it's safe to assume you can keep that food in your diet. However, don't add it back in for good until you've tested all the other foods you've eliminated. If and when symptoms do occur, eliminate that food for another week or two and then try it again to confirm the reaction.

How to do a modified elimination diet

You can also try a modified elimination diet; it is slightly less intensive. Instead of eliminating all possible food triggers, you can eliminate one group of foods first–like citrus fruits or legumes–for the two-week period. If symptoms don't improve, you eliminate another group of potential trigger foods (while still not consuming the first group of foods), and so on until you've deleted a group of food that finally alleviates symptoms-it will be the one most recently removed from the diet. Then, one at a time, you can reintroduce the other food groups back into your diet, remaining attentive for any reactions that could still occur.

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7 things to know before starting an elimination diet

It's possible for food triggers to change over time. You may want to repeat elimination diets every few years to see if you're no longer sensitive to foods that once caused you issues.
While it seems ironic, it is possible to have a food sensitivity to foods you crave and enjoy eating.
In the first few days of an elimination diet, symptoms may become worse before they get better. However, if they get significantly worse or symptoms last for more than a day, reach out to your doctor.
If a food you're reintroducing causes an instantaneous, severe allergic reaction (major rash or throat swelling, for example), get medical attention immediately and avoid future elimination diets without a physician present.
Make sure that you read all labels and that you know all the different words a particular ingredient can be called. You may also want to avoid caffeine, alcohol, aspartame, MSG, nitrates and sulfites while on an elimination diet, as these ingredients can sometimes cause symptoms similar to those of a sensitivity. Pay careful attention when eating out, too, as it's more difficult to be sure of what exactly is in your food. Make sure you specify with the wait staff what allergens you're avoiding.

The eight most common food allergens aren't the only possible foods you might eliminate. Some people experience GI issues and allergy-like reactions from artificial sweeteners, alcohol, yeast, citrus, coffee, corn, black tea, sugar and chocolate.
Elimination diets can be helpful for other health issues as well. Inflammatory conditions, such as psoriasis and arthritis, can be triggered by foods. Irritable bowel syndrome (IBS) may also be made worse by the foods you eat. An elimination diet may help you identify triggers, avoid them and ease symptoms.

What comes after an elimination diet?

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Elimination diets are not perfect, and they do not always present straightforward evidence as to which foods may be causing symptoms. Other factors, such as stress or hormones, can interfere with the diet results, too. You may have to try several different eliminations until you pinpoint the problematic food(s).

Also, it's important to get an accurate diagnosis from an allergist. This can help you avoid a potentially unnecessary diet, and it can ensure you have proper medications to handle future reactions. An allergist can help determine if you need to have emergency epinephrine shots on hand (such as EpiPens); or, in the case of an intolerance, they can offer you ways to aid digestion, such as starting to take Lactaid pills to help digest lactose.

Keep in mind that eliminating a particular food doesn't just mean you're eliminating the "bad" part of it that doesn't agree with you; it also means you could be eliminating a potentially healthful food and key nutrients. It's important to make sure you're getting ample nutrition both during and after your diet, once you've eliminated a food or food group. For example, if you are no longer eating dairy, it's important that you make sure you're getting enough calcium, vitamin D and protein from other dietary sources. Talk to a registered dietitian and/or allergist to discuss taking a multivitamin or other supplement.

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