Effects of short-term carbohydrate or fat overfeeding on energy expenditure and plasma leptin concentrations in healthy female subjects.
OBJECTIVE
To determine the effects of excess carbohydrate or fat intake on plasma leptin concentrations and energy expenditure.


METHODS
Ten healthy lean females were studied: (a) during a 3 day isoenergetic diet (ISO); (b) during 3 day carbohydrate overfeeding (CHO OF); and (c) during 3 day fat overfeeding (FAT OF). During each test, basal metabolic rate, the energy expended during mild physical activity and recovery, and 24 h energy expenditure (24 h EE) were measured with indirect calorimetry. The concentrations of glucose and lactate were monitored in subcutaneous interstitial fluid over a 24 h period using microdialysis. Plasma hormone and substrate concentrations were measured in a blood sample collected in the morning of the fourth day.


RESULTS
CHO OF increased plasma leptin concentrations by 28%, and 24 h EE by 7%. Basal metabolic rate and the energy expended during physical activity were not affected. FAT OF did not significantly change plasma leptin concentrations or energy expenditure. There was no relationship between changes in leptin concentrations and changes in energy expenditure, suggesting that leptin is not involved in the stimulation of energy metabolism during overfeeding. Interstitial subcutaneous glucose and lactate concentrations were not altered by CHO OF and FAT OF.


CONCLUSIONS
CHO OF, but not FAT OF, increases energy expenditure and leptin concentration.
Dirlewanger
M
M
Institute of Physiology, University of Lausanne, Switzerland.
di Vetta
V
V
Guenat
E
E
Battilana
P
P
Seematter
G
G
Schneiter
P
P
Jéquier
E
E
Tappy
L
L
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000273:Adipose Tissue / Q000737:chemistry; D000328:Adult; D001481:Basal Metabolism; D002153:Calorimetry, Indirect; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D004435:Eating; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise; D005110:Extracellular Space / Q000737:chemistry; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000032:analysis; D006801:Humans; D007773:Lactates / Q000032:analysis; D020738:Leptin / Q000097:blood*; D017551:Microdialysis; D013997:Time Factors
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007773:Lactates; D020738:Leptin; D005947:Glucose; D020155:3-Hydroxybutyric Acid