Leptin levels are associated with fat oxidation and dietary-induced weight loss in obesity.
OBJECTIVE
To examine the relationship between fasting plasma leptin and 24-hour energy expenditure (EE), substrate oxidation, and spontaneous physical activity (SPA) in obese subjects before and after a major weight reduction compared with normal weight controls. To test fasting plasma leptin, substrate oxidations, and SPA as predictive markers of success during a standardized weight loss intervention.


METHODS
Twenty-one nondiabetic obese (body mass index: 33.9 to 43.8 kg/m(2)) and 13 lean (body mass index: 20.4 to 24.7 kg/m(2)) men matched for age and height were included in the study. All obese subjects were reexamined after a mean weight loss of 19.2 kg (95% confidence interval: 15.1-23.4 kg) achieved by 16 weeks of dietary intervention followed by 8 weeks of weight stability. Twenty-four-hour EE and substrate oxidations were measured by whole-body indirect calorimetry. SPA was assessed by microwave radar.


RESULTS
In lean subjects, leptin adjusted for fat mass (FM) was correlated to 24-hour EE before (r = -0.56, p < 0.05) but not after adjustment for fat free mass. In obese subjects, leptin correlated inversely with 24-hour and resting nonprotein respiratory quotient (r = -0.47, p < 0.05 and r = -0.50, p < 0.05) both before and after adjustments for energy balance. Baseline plasma leptin concentration, adjusted for differences in FM, was inversely related to the size of weight loss after 8 weeks (r = -0.41, p = 0.07), 16 weeks (r = -0.51, p < 0.05), and 24 weeks (r = -0.50, p < 0.05).


CONCLUSIONS
The present study suggests that leptin may have a stimulating effect on fat oxidation in obese subjects. A low leptin level for a given FM was associated with a greater weight loss, suggesting that obese subjects with greater leptin sensitivities are more successful in reducing weight.
Verdich
C
C
Research Department of Human Nutrition, Centre for Food Research, The Royal Veterinary and Agricultural University, DK-1958 Frederiksberg C, Denmark.
Toubro
S
S
Buemann
B
B
Holst
J J
JJ
Bülow
J
J
Simonsen
L
L
Søndergaard
S B
SB
Christensen
N J
NJ
Astrup
A
A
D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D002153:Calorimetry, Indirect; D016022:Case-Control Studies; D004038:Diet, Reducing; D004734:Energy Metabolism; D006801:Humans; D020738:Leptin / Q000097:blood*; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000178:diet therapy / Q000503:physiopathology*; D010084:Oxidation-Reduction; D015431:Weight Loss / Q000502:physiology*
D020738:Leptin