[Leptin and neuropeptide Y serum levls in young obese during weight loss]

Correlations between serum leptin (LEP) and BMI and the percentage of fat mass (FM), as well as differences between male and female serum levels and their behaviour during weight loss have already been extensively described in adult obesity, whereas few cases have been examined in child and adolescent obesity. There are also few studies of the alterations in NPY in peripheral blood in obese subjects during weight loss.

This study aimed to evaluate the correlations between LEP and BMI, FM% and NPY in 72 obese subjects, with BMI > 35 (29 males and 43 females) aged between 9.6 and 19.8 years old, during weight loss together with any differences between the sexes.

LEP was positively correlated in both sexes with BMI and FM%, whereas no correlation emerged with NPY; LEP levels decreased gradually during weight loss, whereas no changes were observed in NPY except during the first phases of weight loss in males when the decrease was significant. LEP concentrations were significantly higher in females, who also showed a higher FM% with equal BMI. No difference was observed between NPY levels in both sexes.

The authors conclude that: 1) the behaviour of LEP in child-adolescent obesity is broadly comparable to that described in adult obesity; 2) the highest LEP concentrations with equal BMI in females appear to reflect the different body composition of the two sexes given that females have a higher FM%; 3) the control exerted by LEP on hypothalamic NPY cannot be seen in peripheral blood and no differences emerged between the two sexes.