Inclusion Criteria:  On a gluten-free diet for ≥ 4 weeks Willing to consume gluten for research For the celiac disease arm, diagnosis confirmed by serology and/or histology  Exclusion Criteria:  Pregnancy Wheat allergy Type 1 diabetes BMI z-score < -2 History of more than minimal symptoms following gluten exposure on a gluten-free diet Comorbid condition that in the opinion of the investigator would interfere with study participation or would confound study results