Body Mass Index Status in Italian Children with Celiac Disease at Diagnosis and After 12–18 Months on a Gluten-Free Diet: A Multicenter Retrospective Study

<b>Background/Objectives</b>: The distribution of body mass index (BMI) categories at celiac disease (CD) diagnosis in children is changing, and the impact of a gluten-free diet (GFD) on BMI status remains incompletely understood. We aimed to evaluate the distribution of BMI categories at CD diagnosis and their changes after 12-18 months on a GFD in Italian children. <b>Methods</b>: Children and adolescents aged 0-18 years who received a new diagnosis of CD at 23 Pediatric Gastroenterology referral centers in Italy were retrospectively enrolled. We analyzed their BMI status at diagnosis, classifying them as underweight, normal weight, overweight, or obese. BMI changes were assessed after 12-18 months on a GFD. <b>Results</b>: Among the 4967 children (mean age 7.1 ± 4.1 years, M:F = 1827:3140), 4.4% were underweight, 77.5% normal weight, 12.7% overweight, and 5.4% obese at diagnosis. Overweight/obese children were more likely to have a family history of CD, associated conditions, and an asymptomatic presentation. After 12-18 months of GFD, 55.7% of underweight children achieved normal weight, and 23% of overweight/obese reverted to normal weight. Conversely, 10.9% of normal-weight children and 3.2% of underweight children became overweight/obese. <b>Conclusions</b>: At diagnosis, most children were normal weight, but 18.1% presented with overweight/obesity. After 12-18 months on a GFD, BMI normalized in over half of underweight but in fewer than one-quarter of overweight/obese subjects.