Circadian and ultradian components of hunger in human non-homeostatic meal-to-meal eating

摘要

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 23-26kg/m2 engaged in exercise (EX) and sedentary (SED) trials. Weight maintenance meals were provided at 6h intervals with an ad libitum meal at 13h in study 1 and 21h snack in study 2. EE during IM intervals was measured by indirect calorimetry and included EX EE of 801kcal in study 1, and 766-1051kcal 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.