elimination diet

noun
  1. a diet regimen aimed at identifying foods or additives that may be causing an allergy or other symptom, and usually involving the removal of suspected foodstuffs from the diet to see if the symptoms disappear, then adding them back one at a time to see which ones make the symptoms recur.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

elimination diet in Medicine

elimination diet

n.
  1. A diet designed to detect what foodstuffs cause allergic reactions by separate and successive withdrawal of foods from the diet until the food that causes the symptoms is discovered.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.