An elimination diet is the structured diet in which different foods are eliminated one at a time in order to identify a trigger — the clinical tool for diagnosing food intolerances and allergies. Under dietetic supervision, the patient removes the suspect foods completely for a period, waits for symptoms to settle, then reintroduces each food singly while watching for their return. Common targets are milk, egg, wheat, soy, nuts, and fish. The method is powerful because it produces direct evidence — symptoms that vanish on removal and return on challenge — but it demands discipline and professional oversight: unsupervised elimination risks nutritional deficiency and false conclusions. It remains the gold standard for diagnosing non-IgE-mediated food reactions, where blood tests cannot give the answer.