How to Do an Elimination Diet, and Why Everyone Needs to Do One

By: Courtney Sperlazza, MPH
March 19, 2020

  • People do elimination diets to identify their food sensitivities and see if they feel better by avoiding those foods.
  • The process involves avoiding potentially-reactive foods completely for a few weeks, then reintroducing those foods into the diet one at a time to identify whether they produce a reaction in your body.
  • It’s a good idea to do an elimination diet at least once — you won’t know whether you’re performing optimally unless you test for food intolerances.

Do you have a food intolerance? You may have mystery symptoms that seem to come and go, or symptoms that seem to be there all the time. You may have gone to the doctor, who told you that you need to get more sleep, or that everyone starts to feel this way by a certain age. Or maybe you have no noticeable symptoms whatsoever, but you know you don’t have as much energy and brain power as you could.

The answer to those nagging issues might be on your plate. Estimates vary widely, but experts say that as much as 20% of the population suffers from a food intolerance.[1] People are becoming more and more aware of food intolerances, and those who identify their food sensitivities can see amazing results simply by avoiding those foods. One easy way to identify food intolerances is by doing an elimination diet.

What is an elimination diet?

An elimination diet is a way to test yourself for food sensitivities. The process involves taking a few weeks to completely avoid foods known for causing sensitivities, then reintroducing them into the diet one at a time to identify whether a food might be causing inflammation, headaches, skin issues or other side-effects. By eliminating that food from your diet, you might discover a new, improved level of performance.

What can you eat on an elimination diet?

Notebook open next to produce on table

The trickiest part about an elimination diet is deciding which foods are most likely to cause a reaction. Luckily, that part is done for you. The Bulletproof Diet Roadmap makes an elimination diet easy.

The Roadmap takes into account how likely a food is to cause inflammation and reactions in your body. Eat from the Roadmap’s green zone during your elimination period. These foods include grass-fed, organic meats, most plant-based whole foods and some plant-based products like MCT oil (which comes from coconuts). They typically don’t cause the reactions you’d get from other inflammatory foods, like stomach upset or brain fog.

Just avoid these foods during your elimination diet:[2]

  • Dairy
  • Eggs
  • Gluten (including barley, oats, rye and wheat)
  • Fish and shellfish
  • Nightshades (tomatoes and onion)
  • Citrus (contain high amounts of potentially reactive antioxidants)
  • Soy
  • Peanuts
  • Tree nuts
  • Corn
  • Non-organic beef, which may contain the biogenic amines histamine, tyramine, octopamine and phenylethylamine known to potentially cause reactions
  • Sweets or candy containing refined sugar, artificial colors and flavors

How long does the elimination diet take to work?

Air fryer Brussels sprouts

This depends on your body. Start with a diet of low-reaction foods for two weeks, or until your reactions stop. It takes time for your body to flush the trigger foods from your system, and even longer for your body to stop reacting and your symptoms to clear. If your reactions don’t improve, keep going for up to four weeks.

If you don’t experience relief in a month, see your doctor. Food may not be the problem at the root of your symptoms.

Symptoms of food sensitivities

Woman holding bridge of nose

You might think of food allergies as the instantaneous, life-threatening type called anaphylaxis or anaphylactic shock. Typical to seafood and peanut allergies, this allergic response causes a massive release of histamines in the body. This reaction causes full-body swelling, including swelling of the lungs and throat, which can block the airway and cause suffocation.[3]

Food allergies and intolerances can range from a reaction this severe to a reaction that’s barely noticeable or not noticeable at all. Because food intolerances present in so many different ways often you might blame your symptoms on something else entirely. Some of these less noticeable reactions to foods include:

  • Dry skin
  • Bloating
  • Itching
  • Digestive upset
  • Fatigue
  • Headaches
  • Stomach aches
  • Joint aches and pains
  • Migraines

How your body reacts to different foods is based on your individual chemistry. The key is to be mindful — take the time and pay attention to how your body reacts to what you eat.

Why everyone should do an elimination diet at least once

Silhouette of person outside

Even if you don’t think you have any symptoms or food sensitivities, it’s a good idea to do an elimination diet at least once. Here’s why.

More energy and mental clarity

If your body is reacting to something you eat on the regular, chances are you don’t know how potentially good you can feel because your body is in reaction mode every single day. After the initial detox period of a few days, many people feel more energy and clarity than ever during an elimination diet.

If you come out of the initial elimination diet slump feeling like a superhero, that’s a big indication that certain foods affect you. You’ve got little to lose for what might be an incredible gain in performance.

Identify foods that cause inflammation

Between stress, pollutants, chemicals in our food and water and other environmental stressors, modern society deals with a lot of inflammation.

Your inflammatory response is an important part of your immune system, and you need it to rally when necessary. You also need it to turn off when the work is done. If your immune system stays engaged long-term, you have chronic inflammation. Over time, it can chip away at healthy cells and tissues until things have gone too far, and you end up with real damage and disease.

Symptoms of chronic inflammation are subtle, to the point that it can be imperceptible to you — and your doctor. An elimination diet will reveal whether a food is contributing to chronic inflammation. If you’re experiencing low-level symptoms all the time, like feeling tired, foggy, achy or itchy, you get used to it. You might even think it’s normal. When you feel amazing for a few weeks, symptoms are more noticeable when they come back again after you eat the food you’ve been avoiding.

When you bring food back, take notice of everything happening in your body and mind. Your body has a way of making clear when something isn’t working well. All you need to do is pay attention.

How to do an elimination diet

Notebook on table next to food

Start with the Bulletproof Diet Roadmap. Eat from the Roadmap’s green zone, while avoiding eggs and dairy during your elimination period. You’ll know which foods to eat that are healthful, nourishing and, most importantly, delicious.

Here’s how to do an easy elimination diet, using the Bulletproof Diet Roadmap as a cheat sheet:

  1. Eat exclusively from the green zone for at least two weeks, but skip eggs and dairy for now. If you had noticeable reactions that start to improve, like stomach upset or energy swings, keep going until your symptoms are noticeably improved.
  2. Make a list of foods you want to test for your body’s reaction.
  3. Choose one test food to reintroduce into your diet. Eat it with abandon for three days.
  4. Take detailed notes on how you feel, and make a point to notice everything you’re feeling. No matter how small it seems, write everything down.
  5. After day three, go back to only green zone foods for three to four days, until you’re feeling back to normal again. Then repeat steps 3-5 until you’re through your entire list of test foods.

To make it easy for you, the free Bulletproof 30 Day Upgrade has a built-in elimination diet plan with a journal that will help you zero in on what foods to enjoy and which ones to avoid.


Give us 30 days and we'll give you more energy. Get tips, recipes and more that will help you become the best version of YOU.

Or, you can take the shortcut

Drop of blood on fingertip

There are several tests you can do to see if you have food sensitivities. Two of the more reliable ones include:

  • Viome: Viome combines information from a microbiome test with a metabolic test to see how your body and the flora in your digestive system interact with specific foods. You’ll get a personalized plan to stay balanced and run at maximum power, without being slowed down by food sensitivities.
  • EverlyWell: EverlyWell involves pricking your finger and dotting a card with a few drops of blood to test IgG reactivity (a measure of an immune response) for 96 different foods. (Enter bulletproof at checkout for 15% off of your order.)

Maybe you have mystery symptoms, or you suspect you’re not performing as well as you could. After a short experiment, you’ll have a fairly good idea of what you can eat and what to avoid. It’s not as difficult as it seems. Give it a month and go for it. You’ll be glad you did!


Give us 30 days and we'll give you more energy. Get tips, recipes and more that will help you become the best version of YOU.

This is an update of an article originally published November 2018.