Background The metabolically healthy (MH) and metabolically unhealthy (MUH) phenotypes have been discussed in the literature but the factors related to the development of these phenotypes, in adolescents with adwuate and high body mass index (BMI), are not yet fully understood. Objective To evaluate the relationship between age during the menarche, serum leptin concentrations, body composition and MH and MUH phenotypes, in adolescents with adequate and high BMI. Methods Observational and cross-sectional study made up of female adolescents attended at Centro de Referência do Adolescente, in Macaé, Rio de Janeiro. The stage of sexual maturation and the age at menarche were analyzed based on the self-declaration of the participants. The menarche was considered early (EM) when the first menstruation occurred up to 11 years of age; normal (NM) between 12 and 14 years old; and late after 15 years of age. Body mass and height were measured to calculate BMI, and the following body variables were analyzed: waist circumference (WC), waist/height ratio (WHR), body fat (BF%), fat body mass index (FBMI) and fat-free mass index (FFMI), visceral adiposity index (VAI). In addition, cardiometabolic components and serum leptin concentrations were measured.Results 82% (n=114) of the adolescents were classified as MH and 18% (n=25) as MU. The mean age at menarche was 11.79 ± 1.39 years. 60% (n=15) of EM and 84% (n=21) of inadequacy of serum leptin were identified in the MUH group. Among eutrophic women, there was 85.7% (n=6) of inadequate WC among MUH adolescents and 2.5% (n=2) among MH ones ( p <0.01), while among adolescents with high BMI, 88.9% (n=16) and 28.6 (n=10) of the MUH and MH groups, respectively, showed inadequacy of this variable ( p <0.01). Among MUH adolescents, there was a strong correlation between the age at menarche and BF% (r= - 0.63 p <0.01); VAI and TG (r=0.87 p <0.01), BF% (r=0.63 p <0.01) and FFM (r=0.61 p <0.01). Conclusion Age at menarche, serum leptin and WC are related to the MUH phenotype in adolescents and should be investigated, during clinical practice, to help prevent cardiometabolic diseases in adulthood.