Food is medicine.

But it can also be poison.

It depends on the food—and the person. For some people, with certain conditions, specific “trigger” foods can bring on symptoms such as skin rashes, wheezing, bloating, diarrhea, constipation, cramps, headaches, fatigue and mood swings.

The best way to identify your trigger foods? An elimination diet, a kind of experiment-of-one, conducted hand-in-hand with a health professional. To find out how to do it right, we spoke with Maggie Moon, MS, RD, a New York–based registered dietitian and author of The Elimination Diet Workbook: A Personal Approach to Determining Your Food Allergies.


An elimination diet is the classic way to identify food allergies, which can bring on symptoms such as hives, often soon after the food is eaten. It can also identify more subtle food intolerances—to lactose sugar in dairy foods, for example, or gluten protein in wheat—which can cause immunological and digestive problems that may take hours, even days, to cause symptoms. If you have irritable bowel syndrome (IBS), for example, you may want to begin eliminating “FODMAP” foods that often are at the root of the problem—to find out which ones are your triggers. Elimination diets can often help improve symptoms for conditions as different as migraines, chronic sinus congestion, adult acne, rheumatoid arthritis and asthma.

The goal of an elimination diet is to identify your specific problem foods by removing possible triggers and then slowly reintroducing them—while monitoring your symptoms. That way, you find out which foods are really causing your symptoms—and which ones you can safely eat.


Before you get going, check with your doctor. That’s especially important if you’ve ever had a life-threatening allergic reaction (anaphylactic shock), have battled an eating disorder or are on medications that are diet-sensitive, such as the heart drug warfarin (Coumadin).

Even if you don’t have such a medical concern, the best way to be successful is to work with a qualified health professional such as an allergist, gastroenterologist, integrative physician or naturopath. He or she may refer you to a nutritionist, such as a registered dietician nutritionist—or you may start with a nutritionist—who can be your coach through the process, providing support and making sure you’re meeting your nutritional needs.

A few more tips for success…

Be honest. First, you’ll need to be scrupulous as you keep track of what you eat and how you feel for several weeks, before you start the diet.

Accept change. The new way of eating will restrict your choices and limit your options, and it can be a challenge to learn how to cook different foods than you are used to—and then make time to cook them—and to adjust to a new way of eating out.

Get support. Your spouse, partner, kids and friends will be affected by your new diet, so you’ll need to explain what you plan to do and why.


1. Assess

During this phase, assess your dietary habits by writing down what you eat and how it makes you feel. Your record needs to be as honest, detailed and accurate as possible.

You can track food and symptoms with an existing spreadsheet (there’s one in her book), but you can also create your own with a pen and paper. Make four columns, labeled “Meal,” “Food/Drink (How much),” “Ingredients” and “Symptoms.” For the symptoms column, describe when they start and when they end and rate the intensity on a scale of 1 to 10. Keeping track for two to four weeks should allow you to note immediate and delayed symptoms. Ms. Moon likes the mySymptoms Food & Symptom Tracker app from SkyGazer Labs. Available on iTunes and on Google Play for Android devices, it allows you to enter foods, ingredients, supplements, medications and drinks—as well as different kinds of exercise—and track your symptoms.

Tip: This needs to be an honest baseline, so eat the way you normally would. While symptoms may persist during this time, keep in mind that soon you’ll be able to say good-bye to them.

2. Get Ready

Once you’ve identified possible food triggers remove them from your kitchen, pantry, office and car to make it easier to stick to your “safe” foods and avoid temptation. If that’s not feasible (because you live with others, for example), try to put the “safe” foods you’ll be eating now in a separate place.

Prepare yourself, too, by acknowledging that the elimination diet is not an easy process and you will have ups and downs. Symptoms could flare up and might even seem worse at the start of an elimination diet. Have patience—the end results will be worth it. Just knowing this will enable you to follow through.

Tip: This is a good time to create meal plans and grocery lists of allowed foods.

3. Avoid (Eliminate)

Now it’s time to stop eating all the possible trigger foods. Continue to keep track of what you eat and how you feel, along with overall levels of energy, body aches, etc.

After a week, if symptoms have improved, you can move to the challenge phase. However, if symptoms persist after two to four weeks, it’s time to take a closer look at your food and symptom tracker. Circle foods that precede symptoms, and eliminate the foods that show up most often first.

Tip: If you still experience symptoms after eliminating possible food triggers, consider the possibility that food is not the reason for your symptoms after all. Make an appointment with your health-care professional to pinpoint the problem.

4. Challenge

 In this step, you’ll reintroduce foods to confirm that they are safe for you through a food challenge. You’ll test one and only one potential trigger food in the morning and then monitor for symptoms.

Here’s how: Put a tiny amount of the food inside your lower lip for two minutes, and monitor for a half hour before trying a small amount, which varies by food. For example, if the food challenge is milk, and you normally drink eight ounces a day, a small amount would be about an ounce.

Assuming there are no symptoms, you can increase the amount of the same food at lunchtime, while again monitoring how you feel. Repeat at dinner with an even larger portion if there were no symptoms after lunch. Keep track of what you’re eating and how you feel to get the most accurate picture of which foods are causing you to feel ill.

To monitor for any delayed symptoms that don’t show up right away, use a “washout” period of two weeks, which means going back to the baseline elimination diet in Step 2. If all goes well, you can add the “challenge” food to your list of “safe” foods. Keep in mind that the challenge phase can last for several weeks or more depending on how many challenge foods you need to test.

Tip: Test foods one at a time, but keep even the “safe” foods out of your diet until all of the food challenges are done. This assures that only one variable is being tested at a time without potential confounding factors.

5. Change

In this step, you learn how to follow a maintenance diet. The elimination diet plus your list of “safe” foods can be used as a foundation for a long-term maintenance diet. Using a list of all your safe foods, the easiest way to plan meals is to identify a protein, vegetables and a grain or starch per meal.

Tip:  It varies by individual, but a good rule of thumb is to add a new food for two to four weeks and see how you react.


The ultimate purpose of an elimination diet is to reestablish a friendly and healthy connection with food instead of having an adversarial relationship with what you’re eating. It can enable you to live a healthier life by teaching you how to make and eat food that is healthier for you. You may even lose weight. It’s time to make peace with the food you eat.