BACKGROUND: Optimal nutritional status (NS) in cystic fibrosis (CF) is associated with better lung function and increased overall survival. This study estimated the prevalence of malnutrition and obesity among CF patients in a tertiary center.METHODS: In a cross-sectional study of 68 CF patients (33 female; 37 children/adolescents) weight, height, body composition, respiratory function (% of the predicted forced expiratory volume in 1 s; FEV1%pred ) and serum lipids were measured; body mass index (BMI), BMI standard deviation score (BMI-SDS) and BMI percentiles were calculated; Pseudomonas colonization, pancreatic insufficiency, diabetes mellitus (CFDM), liver disease (CFLD) and genotype were recorded; NS was classified according to the 2005 Cystic Fibrosis Foundation (CFF) criteria. Frequency distributions and associations between anthropometric and clinical parameters (univariate/multivariate) were calculated.RESULTS: Mean age (±SD) was 19.81 ± 8.98 years. Regarding NS: 22.1% were malnourished, 13.2% overweight/obese and 29.4% had optimal NS. Pancreatic function (PF), Pseudomonas colonization, CFDM, CFLD and genotype differed significantly among the three groups. FEV1%pred was significantly higher among overweight/obese patients and correlated positively with anthropometric characteristics as well as serum cholesterol and negatively with age. BMI-SDS was associated with PF, FEV1%pred and CFDM. Among overweight/obese patients 89.9% had adequate PF and 66.7% carried mutations other than F508del. No patient had any traits of metabolic syndrome.CONCLUSIONS: Despite appropriate management only one-third of the present patients had optimal NS. One-fourth were malnourished and a significant percentage were overweight/obese. The latter were mostly carriers of mutations other than F508del and had better pulmonary function. CF patients require intensive monitoring for both malnutrition and overweight/obesity.