title: Preprandial ghrelin is not affected by macronutrient intake, energy intake or energy expenditure.
abstract: BACKGROUND
  Ghrelin, a peptide secreted by endocrine cells in the gastrointestinal tract, is a hormone purported to have a significant effect on food intake and energy balance in humans. The influence of factors related to energy balance on ghrelin, such as daily energy expenditure, energy intake, and macronutrient intake, have not been reported. Secondly, the effect of ghrelin on food intake has not been quantified under free-living conditions over a prolonged period of time. To investigate these effects, 12 men were provided with an ad libitum cafeteria-style diet for 16 weeks. The macronutrient composition of the diets were covertly modified with drinks containing 2.1 MJ of predominantly carbohydrate (Hi-CHO), protein (Hi-PRO), or fat (Hi-FAT). Total energy expenditure was measured for seven days on two separate occasions (doubly labeled water and physical activity logs).
  
  
  RESULTS
  Preprandial ghrelin concentrations were not affected by macronutrient intake, energy expenditure or energy intake (all P > 0.05). In turn, daily energy intake was significantly influenced by energy expenditure, but not ghrelin.
  
  
  CONCLUSIONS
  Preprandial ghrelin does not appear to be influenced by macronutrient composition, energy intake, or energy expenditure. Similarly, ghrelin does not appear to affect acute or chronic energy intake under free-living conditions.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Diet and Human Performance Laboratory, Beltsville Human Nutrition Research Center, Beltsville, MD 20705, USA. pauld@ba.ars.usda.gov
authors.forename: David R
authors.initials: DR
authors.lastname: Paul
authors.forename: Matthew
authors.initials: M
authors.lastname: Kramer
authors.forename: Donna G
authors.initials: DG
authors.lastname: Rhodes
authors.forename: William V
authors.initials: WV
authors.lastname: Rumpler
mesh_terms: D000328:Adult; D001628:Beverages; D001835:Body Weight / Q000187:drug effects; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D054439:Ghrelin; D006801:Humans; D008297:Male; D036361:Peptide Hormones / Q000378:metabolism*
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones
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