title: Assessment of nutritional status and body composition in children using physical anthropometry and bioelectrical impedance: influence of diurnal variations.
abstract: BACKGROUND
  To observe whether there are diurnal variations when assessing children's body composition, using physical anthropometric and bioelectrical impedance (BI) methods.
  
  
  METHODS
  In 32 children (18 females and 14 males) aged between 7.1 and 14.9 years, weight, height, arm circumference (AC), four skinfolds, and total body impedance (Z) were measured at 8 A.M., 12 noon, 4 P.M., and 8 P.M. on the same day. Body mass index (BMI), skinfolds sum (SS), total body water (TBW), fat-free mass (FFM), and fat mass (FM) were also calculated at these times.
  
  
  RESULTS
  Height at 8 P.M. was 1.156 +/- 0.54 cm less than at 8 A.M. (P < 0.001) and BMI increased 0.434 +/- 0.29 kg/m2 at 8 P.M. (P < 0.001). Weight, SS and AC underwent no significant changes in the course of the day. Z was 5.83% less at 8 P.M. than at 8 A.M. (P < 0.001), yielding a TBW and FFM increase at 8 P.M. of 0.855 +/- 1.061 and 1.173 +/- 1.47 kg, respectively (P < 0.001).
  
  
  CONCLUSIONS
  In children there is a diurnal decrease in height, impedance and FM, and an increase in BMI, TBW, and FFM. These factors must be taken into account when using such methods for assessing nutritional status in childhood.
authors.affiliation: Departamento de Pediatría, Facultad de Medicina, Universidad de Zaragoza, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Rodríguez
authors.forename: L A
authors.initials: LA
authors.lastname: Moreno
authors.forename: A
authors.initials: A
authors.lastname: Sarría
authors.forename: J
authors.initials: J
authors.lastname: Fleta
authors.forename: M
authors.initials: M
authors.lastname: Bueno
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000886:Anthropometry; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002940:Circadian Rhythm; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D009752:Nutritional Status; D012885:Skinfold Thickness