Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine.
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.
Zauner
C
C
Intensive Care Unit, the Department of Internal Medicine IV, Universityof Vienna, Vienna, Austria.
Schneeweiss
B
B
Kranz
A
A
Madl
C
C
Ratheiser
K
K
Kramer
L
L
Roth
E
E
Schneider
B
B
Lenz
K
K
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
D001786:Blood Glucose; D005227:Fatty Acids; D020155:3-Hydroxybutyric Acid; D009638:Norepinephrine