title: Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine.
abstract: BACKGROUND
  The effects of food restriction on energy metabolism have been under investigation for more than a century. Data obtained are conflicting and research has failed to provide conclusive results.
  
  
  OBJECTIVE
  The objective of this study was to test the hypothesis that in lean subjects under normal living conditions, short-term starvation leads to an increase in serum concentrations of catecholamines and thus to an increase in resting energy expenditure.
  
  
  METHODS
  Resting energy expenditure, measured by indirect calorimetry, and hormone and substrate concentrations were measured in 11 healthy, lean subjects on days 1, 2, 3, and 4 of an 84-h starvation period.
  
  
  RESULTS
  Resting energy expenditure increased significantly from 3.97 +/- 0.9 kJ/min on day 1 to 4.53 +/- 0.9 kJ/min on day 3 (P < 0.05). The increase in resting energy expenditure was associated with an increase in the norepinephrine concentration from 1716. +/- 574 pmol/L on day 1 to 3728 +/- 1636 pmol/L on day 4 (P < 0.05). Serum glucose decreased from 4.9 +/- 0.5 to 3.5 +/- 0.5 mmol/L (P < 0.05), whereas insulin did not change significantly.
  
  
  CONCLUSIONS
  Resting energy expenditure increases in early starvation, accompanied by an increase in plasma norepinephrine. This increase in norepinephrine seems to be due to a decline in serum glucose and may be the initial signal for metabolic changes in early starvation.
authors.affiliation: Intensive Care Unit, the Department of Internal Medicine IV, Universityof Vienna, Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Zauner
authors.forename: B
authors.initials: B
authors.lastname: Schneeweiss
authors.forename: A
authors.initials: A
authors.lastname: Kranz
authors.forename: C
authors.initials: C
authors.lastname: Madl
authors.forename: K
authors.initials: K
authors.lastname: Ratheiser
authors.forename: L
authors.initials: L
authors.lastname: Kramer
authors.forename: E
authors.initials: E
authors.lastname: Roth
authors.forename: B
authors.initials: B
authors.lastname: Schneider
authors.forename: K
authors.initials: K
authors.lastname: Lenz
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D005227:Fatty Acids / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D012146:Rest; D013217:Starvation
chemical_list: D001786:Blood Glucose; D005227:Fatty Acids; D020155:3-Hydroxybutyric Acid; D009638:Norepinephrine