Using elimination diets to identify food sensitivities

Bowls of vegetables being held and eaten

An elimination diet can be helpful for reducing inflammation and improving gastrointestinal symptoms, and there are many ways to do a diet like this. The basic premise is that you remove/eliminate certain foods for a specified amount of time in an attempt to improve certain symptoms.

Examples of elimination diets:

  • the Whole30 diet
  • the autoimmune protocol diet
  • the low-FODMAP diet
  • the specific carbohydrate diet
  • the six food (dairy, wheat, soy, egg, tree nuts/peanuts and fish/shellfish) elimination diet
  • the four food (dairy, wheat, soy and egg) elimination diet

Some elimination diets will also recommend a reduction or elimination of added sugar, caffeine and alcohol.

An elimination diet should include a planned reintroduction of foods to determine if and how much those foods might be contributing to symptoms. This elimination, followed by challenge or reintroduction, is the tried-and-true method of determining a food intolerance or food sensitivity.

Starting an elimination diet

The first step, or the “elimination phase,” will typically last one to three months. If the elimination diet is going to be helpful in improving symptoms, that improvement should be seen within this time frame.

However, it’s important to realize that an inflammatory reaction from a particular food could continue for up to two weeks after ingestion. Thus, if you “cheat” during the elimination phase, you may never realize the true potential of the elimination. For the best “test,” it’s important to be fairly strict during this elimination phase.

Reintroducing foods on an elimination diet

The timing of moving into the second step, the “reintroduction phase,” is determined based on the improvement of your symptoms. You can start this step once your symptoms have significantly improved or resolved. This is a step that many people tend to rush through.

After weeks of food restriction, it can be very tempting to eat many of those targeted foods within a day or two. If symptoms return quickly thereafter, it will be impossible to know which food or foods were linked to the symptoms.

Should you avoid eating fructans?

For best results, one food should be added back to the diet at a time

In fact, we typically use a detailed protocol of one food for two to three days, with gradual increase of the consumed portion, followed by a “wait and see” phase for three to four days, during which the food is not eaten. This “wait and see” phase is a time to observe your body for delayed symptoms.

Because of the tedious nature of the reintroduction phase, a food and symptom diary is necessary. Sometimes a person might notice benefits that they weren’t expecting. The food and symptom diary should include the name, portion and cooking method of the food in addition to any factors that could impact symptoms, such as inadequate sleep, movement or hydration, menstrual cycle and stress.

It’s helpful to be on the lookout for the following:

  • Gastrointestinal symptoms — such as bloating, abdominal pain, reflux, excessive belching, excessive flatulence, loose stool or diarrhea or constipation
  • Skin changes — such as itchiness, redness or bumps
  • Mood changes — such as irritability or sadness
  • Headaches or brain fog
  • Sleep disturbances
  • Nasal congestion
  • Fluid retention
  • Joint or muscle pain
  • Fatigue

At the end of the reintroduction phase, the goal is to have a wealth of knowledge about how different kinds and quantities of foods make you feel. With this knowledge, you can decide to avoid foods that make you feel unwell or limit them in frequency and quantity so that any adverse symptoms are minimal and manageable.

Of course, it’s best to keep good nutrition principles in mind when working around those limitations and avoidances. Going forward, keep in mind that you will still need to eat a wide variety of whole plant foods while also limiting added sugar and highly processed foods.

Don’t do it alone

Because of the complexity of elimination diets, it’s highly recommended that you work with a registered dietitian (RD) throughout the process. An RD can help you decide what type of elimination diet would be best for you and figure out what to eat in place of your usual foods during the elimination phase. The RD can also help you decipher symptoms and their correlation to specific foods during the reintroduction phase.

Embarking on an elimination diet is a considerable amount of work. Having support throughout the process can be invaluable.

Who shouldn’t try an elimination diet?

A common side effect of an elimination diet is weight loss. Sometimes this is beneficial and sometimes it’s not. Excessive weight loss (more than two pounds a week) should be avoided because this often signals a loss of lean body mass rather than fat loss.

Thus, people who are underweight or those who have a challenge keeping a healthy weight usually aren’t good candidates for an elimination diet. Likewise, pregnant women, lactating women, growing children, adolescents and frail, elderly people aren’t good candidates.

An elimination diet also isn’t appropriate for a person who is being treated for an eating disorder. People with a history of eating disorders should discuss this with an RD before starting an elimination diet. Sometimes the restrictive nature of the elimination phase triggers eating disorder behavior.

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