title: Eating late in the evening is associated with childhood obesity in some age groups but not in all children: the relationship between time of consumption and body weight status in U.S. children.
abstract: BACKGROUND
  Some studies in adults indicate a positive correlation between eating later in the day and overall energy intake as well as body weight status. Thus, the time of food intake may be a risk factor in childhood obesity. This study was designed to describe the proportion of energy consumed in the time from 4 pm to midnight measured in two-hour increments and to determine a potential association between the time of proportion of energy consumed and body weight status.
  
  
  METHODS
  Dietary, anthropometric, and socio-demographic data of 2-18 year olds (N = 11,072) of the National Health and Nutrition Examination Survey (NHANES) 1999-2004 was examined to describe the proportion of total energy consumed within two-hour time periods between 4 pm and midnight. To examine the potential association between eating later in the day and body weight status, generalized estimating equations (GEE) models were used to quantify the effect of time trends (proportion of total energy consumed in each 2-hour time period from 4 pm to 11.59 pm) on body weight status. Analysis was conducted in the total sample and in subgroups stratified by sex, ethnic group (Non-Hispanic white, Non-Hispanic black, Mexican American, Other Hispanic, and Other Race including multi-racial) and age group (2-5, 6-11, and 12-18 year olds). Complex sample survey analysis were used to assess differences at a significance level of p-value < 0.05.
  
  
  RESULTS
  Proportion of energy consumed varied by sex, ethnic group, and age groups between 4 pm and 11.59 pm. Compared to healthy weight children, overweight school-age children consumed significantly higher while overweight adolescents consumed significantly lower proportions of total daily energy with each advancing two-hour time increment.
  
  
  CONCLUSIONS
  The association between the circadian rhythm of eating and body weight status needs to be investigated further to examine the effect of time of consumption on the risk of childhood obesity. Especially longitudinal studies in diverse child populations would help elucidate the importance of time of eating on obesity.
authors.affiliation: Department of Nutrition and Dietetics, East Carolina University, Rivers Building, Greenville, North Carolina 27858, USA. kranzs@ecu.edu.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Eng
authors.forename: David A
authors.initials: DA
authors.lastname: Wagstaff
authors.forename: Sibylle
authors.initials: S
authors.lastname: Kranz