A new research study regarding fluid intake and hydration status in obese versus normal weight children has just been published in the European Journal of Clinical Nutrition. The study at the University of Verona was funded by a donation from the EHI and it assessed whether, and by which mechanisms, hydration status differs between obese and non-obese children.
The abstract of the paper can be read below:
Eur J Clin Nutr. 2015 Oct 14. doi: 10.1038/ejcn.2015.170. [Epub ahead of print] Fluid intake and hydration status in obese vs normal weight children. Maffeis C, Tommasi M, Tomasselli F, Spinelli J, Fornari E, Scattolo N, Marigliano M, Morandi A.
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.
European Journal of Clinical Nutrition advance online publication, 14 October 2015; doi:10.1038/ejcn.2015.170. PMID: 26463726 [PubMed – as supplied by publisher]