Objective: To investigate the nutritional status variation and symptomatology of patients with celiac disease and non-celiac gluten sensitivity after specialized dietary advice Methods: This prospective study included 80 patients with celiac disease and non-celiac gluten sensitivity. Clinical, metabolic, and nutritional variables were collected from medical records, and the symptomatology was investigated by the Metabolic Screening Questionnaire. The variables were assessed on two occasions (T1 - before dietary advice and T2 - after dietary advice) with an interval of three months between T1 and T2 Results: The median age was 42 years. The prevalences of celiac disease and non-celiac gluten sensitivity were 66.2% and 33.8%, respectively. Normal weight prevailed at T1 (58.8%) and T2 (56.3%), but 30.0% of the patients at T1 and 34.9% of the patients at T2 had excess weight. The two conditions had similar symptomatology. The most frequent signs and symptoms on both occasions involved the gastrointestinal tract, followed by energy/activity and emotions. All symptoms decreased significantly after the introduction of a proper diet Conclusion: The patients were normal weight on both study occasions (T1 and T2), and the symptoms improved after dietary advice. Thus, we reinforce the importance of proper dietary management in both clinical conditions to make dietary adjustments that improve these individuals' symptomatology.