title: Interrelationship between circulating leptin concentrations, hunger, and energy intake in healthy subjects receiving tube feeding.
abstract: BACKGROUND
  Tube feeding is an unphysiological route of nutrient delivery, and yet there is a lack of controlled trials examining its effects on appetite, food intake, and factors involved in their control. This study aimed to investigate the relationship between diurnal tube feeding, hunger, food intake, and circulating concentrations of leptin (a putative satiety factor).
  
  
  METHODS
  Six healthy lean men received a continuous nasogastric infusion (9:00 AM to 9:00 PM) of colored water (2 days), liquid feeding (4.2 kJ/mL, energy provision 1 x the initial predicted basal metabolic rate; 3 days), and colored water (2 days). Measurements of hunger (visual analog scales), weighed food intake, and fasting circulating leptin concentrations were made while the subjects were allowed free access to isoenergetically dense food items.
  
  
  RESULTS
  Three days of diurnal nasogastric feeding (mean, 6.9 MJ/d) significantly increased total energy intake (to 19.4 MJ/d; p < .001; analysis of variance [ANOVA]), suppressing oral energy intake by only 17%, with no significant effect on mean daily hunger. Higher levels of energy intake led to a universal rise in circulating leptin concentrations (2.82 to 4.23 ng/mL; p < .004; ANOVA) that was not significantly related to subsequent breakfast energy intake, first rated hunger of the day, timing of morning food consumption, or subsequent mean daily oral energy intake or hunger.
  
  
  CONCLUSIONS
  This study suggests that 3 days of diurnal tube feeding (equivalent to basal metabolic rate) failed to suppress hunger and reduced food intake by only 17%. The rise in circulating leptin concentrations, associated with tube feeding and the increase in total energy intake, failed to predict subsequent hunger or oral energy intake.
authors.affiliation: MRC Dunn Clinical Nutrition Centre, Cambridge, United Kingdom.
authors.forename: R J
authors.initials: RJ
authors.lastname: Stratton
authors.forename: R J
authors.initials: RJ
authors.lastname: Stubbs
authors.forename: M
authors.initials: M
authors.lastname: Elia
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004435:Eating; D002149:Energy Intake / Q000502:physiology*; D004750:Enteral Nutrition; D006801:Humans; D006815:Hunger / Q000502:physiology*; D020738:Leptin; D008297:Male; D011506:Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D020738:Leptin; D011506:Proteins