title: Circadian and ultradian components of hunger in human non-homeostatic meal-to-meal eating.
abstract: A unifying physiological explanation of the urge to initiate eating is still not available as human hunger in meal-to-meal eating may not be under homeostatic control. We hypothesized that a central circadian and a gastrointestinal ultradian timing mechanism coordinate non-deprivation meal-to-meal eating. We examined hunger as a function of time of day, inter-meal (IM) energy expenditure (EE), and concentrations of proposed hunger-controlling hormones ghrelin, leptin, and insulin.
  
  
  METHODS
  In two crossover studies, 10 postmenopausal women, BMI 23-26 kg/m(2) engaged in exercise (EX) and sedentary (SED) trials. Weight maintenance meals were provided at 6h intervals with an ad libitum meal at 13 h in study 1 and 21 h snack in study 2. EE during IM intervals was measured by indirect calorimetry and included EX EE of 801 kcal in study 1, and 766-1,051 kcal in study 2. Hunger was assessed with a visual analog scale and blood was collected for hormonal determination.
  
  
  RESULTS
  Hunger displayed a circadian variation with acrophase at 13 and 19 h and was unrelated to preceding EE. Hunger was suppressed by EX between 10 and 16 h and bore no relationship to either EE during preceding IM intervals or changes in leptin, insulin, and ghrelin; however leptin reflected IM energy changes and ghrelin and insulin, prandial events.
  
  
  CONCLUSIONS
  During non-deprivation meal-to-meal eating, hunger appears to be under non-homeostatic central circadian control as it is unrelated to EE preceding meals or concentrations of proposed appetite-controlling hormones. Gastrointestinal meal processing appears to intermittently suppress this control and entrain an ultradian hunger pattern.
authors: College of Science and Mathematics, Department of Biology and Physical Education, Norwich University, Northfield, VT 05663, United States. Electronic address: ewuorine@norwich.edu.
authors: Elizabeth C
authors: EC
authors: Wuorinen
authors: Katarina T
authors: KT
authors: Borer
mesh_terms: D001066:Appetite / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D018592:Cross-Over Studies; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D054439:Ghrelin / Q000097:blood; D006801:Humans; D006815:Hunger / Q000502:physiology*; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008875:Middle Aged
chemical_list: D054439:Ghrelin; D007328:Insulin; D020738:Leptin
keywords: Circadian; Exercise; Food intake; Ghrelin; Hunger; Insulin; Leptin