Background/Aims: Early vascular dysfunction dysfunction likely to track into adulthood is among the prominent and common consequences of adolescents obesity, The contribution of the perivascular adipose tissue to this dysfunction has not been extensively studied, and it is not known whether it mediates the metabolic or vascular improvements related to a lifestyle intervention. Our aims were to 1) compare the carotid extra-media thickness (cEMT) - whose perivascular adipose tissue is a major component - in obese and control adolescents 2) to characterize the evolution of cEMT and investigate its determinant in response to a 3-month lifestyle program based on diet, exercise training and vitamin D supplementation. Methods: 15 normal-weight (NW) and 20 obese adolescents (OB) comparable in age, male-female distribution and Tanner stage were involved in a controlled trial (NCT02400151) leading to -7.5kg±3.3kg and -10.9±4.7% in BMI z score in the OB group. Macro and microvascular function and structure indices obtained from high-resolution vascular ultrasonography and laser speckle contrast imaging, and biological parameters were assessed pre and post-intervention (obese)/control period. The body composition was assessed with dual-energy x-ray absorptiometry. Results: The cEMT of NW and OB adolescents was not different (632.0±115.3 vs. 640.6±151.4 p=0.856) and did not significantly change with intervention (all p>0.535). In OB, the cEMT change was a strong mediator of the association between the changes in fat mass and leptin but was not directly associated with the improvement of any vascular variable. Conclusion: These results suggest a reversible remodelling in nature of perivascular tissues in adolescent obesity