title: Fluid intake and hydration status in obese vs normal weight children.
abstract: Little is known on the relationship between obesity and hydration levels in children. This study assessed whether and by which mechanisms hydration status differs between obese and non-obese children.
  
  
  
  Hydration levels of 86 obese and 89 normal weight children (age: 7-11 years) were compared. Hydration was measured as the average free water reserve (FWR=urine output/24 h minus the obligatory urine output [total 24 h excreted solutes/97th percentile of urine osmolality of children with adequate water intake, that is, 830 mOsm/kg]) over 2 days. Three days of weighed dietary and fluid intakes were recorded. Non-parametric tests were used to compare variables that were skewed and to assess which variables correlated with hydration. Variables mediating the different hydration levels of obese and normal weight children were assessed by co-variance analysis.
  
  
  
  Obese children were less hydrated than normal weight peers [FWR=median (IQR): 0.80 (-0.80-2.80) hg/day vs 2.10 (0.10-4.45) hg/day, P<0.02; 32% of obese children vs 20% of non-obese peers had negative FWR, P<0.001]. Body mass index (BMI) z-score (z-BMI) and water intake from fluids correlated with FWR (ρ=-0.18 and 0.45, respectively, both P<0.05). Water intake from fluids completely explained the different hydration between obese and normal weight children [FWR adjusted for water from fluids and z-BMI=2.44 (0.44) hg vs 2.10 (0.50) hg, P=NS; B coefficient of co-variation between FWR (hg/day) and water intake from fluids (hg/day)=0.47, P<0.001].
  
  
  
  Obese children were less hydrated than normal weight ones because, taking into account their z-BMI, they drank less. Future prospective studies are needed to explore possible causal relationships between hydration and obesity.
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Maffeis
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Tommasi
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Tomasselli
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: J
authors.initials: J
authors.lastname: Spinelli
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Fornari
authors.affiliation: Chemo-Clinical Analysis Laboratory, Frà Castoro Hospital, San Bonifacio, Verona, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Scattolo
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Marigliano
authors.affiliation: Unit of Pediatric Diabetes and Metabolic Diseases, Department of Life and Reproduction Sciences, University of Verona, Verona, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Morandi
mesh_terms: D002648:Child; D002664:Child Nutritional Physiological Phenomena; D004326:Drinking; D002149:Energy Intake; D005260:Female; D006801:Humans; D056865:Ideal Body Weight / Q000502:physiology*; D008297:Male; D000074267:Organism Hydration Status; D063766:Pediatric Obesity / Q000503:physiopathology*