BACKGROUND: In @entity28 @entity1 , plasma leptin is elevated and correlates with the body mass index (BMI). In @entity28 adults, plasma leptin decreases during @entity353 . Since the leptin system changes dynamically in puberty, we asked whether @entity353 in @entity28 adolescents has similar consequences for plasma leptin as in overweight adults. In plasma, a portion of leptin is bound to several as yet uncharacterised proteins. We therefore studied the possible association of leptin with plasma lipoproteins. SUBJECTS AND METHODS: We measured plasma leptin, lipoprotein @entity165 and apolipoproteins (apo) A-I and B in 34 @entity28 @entity1 (age 12.5+/-1.9 y, relative BMI 165.0+/-28.1%) before and after three weeks of @entity353 in a dietary camp. Lipoprotein binding of endogenous and exogenously radiolabelled leptin was studied by preparative ultracentrifugation. RESULTS: Plasma leptin was higher in @entity28 @entity1 than in normal weight controls and fell from 16.5+/-9.8 ng/ml to 10.0+/-8.6 ng/ml after @entity353 (P < 0.001). In multivariate regression, relative BMI and @entity1675 were significant predictors of baseline leptin and accounted for 38% (P = 0.003) and 15% (P = 0.006) of the variance of baseline leptin concentrations in @entity28 @entity1 . Only the difference in plasma high-density lipoprotein (HDL)- @entity165 independently predicted the change of plasma leptin that was associated with @entity353 , explaining 29% of the variance of leptin changes (P = 0.0032). A substantial portion of both endogenous and exogenously labelled leptin was recovered with HDL isolated by ultracentrifugation. CONCLUSIONS: We conclude that plasma leptin decreases in overweight @entity1 undergoing short term @entity353 . In @entity28 @entity1 , plasma @entity1675 and HDL- @entity165 are independent predictors of leptin concentrations during weight loss, respectively. In addition, HDLs transport a variable portion of leptin in the circulation.

Relation of plasma leptin to lipoproteins in overweight XXXX undergoing @entity353 .

@entity1 :: ('9606', 'Species') :: ['children'] @entity353 :: ('MESH:D015431', 'Disease') :: ['weight reduction'] @entity28 :: ('MESH:D009765', 'Disease') :: ['obese'] @entity1675 :: ('335', 'Gene') :: ['apoA-I'] @entity165 :: ('MESH:D002784', 'Chemical') :: ['cholesterol']
@entity1 :: (9606,Species) :: ['children']
