Obesity phenotypes can be regarded as an indicator of CVD risk factors. The aim of the present study was to determine the prevalence of adolescents with different obesity phenotypes and the role of obesity phenotypes in prediction of the metabolic syndrome (MetS) in adults. For this population-based cohort study, 2159 adolescents aged 11-18 years were included. Subjects were divided into four obesity phenotype groups: metabolically healthy normal weight (MHNW), metabolically healthy obese (MHO), metabolically unhealthy normal weight (MUNW) and metabolically unhealthy obese (MUO). Cox proportional hazard modelling was used to estimate the incidence of the MetS in adults after a median follow-up of 11·3 years. The incidence rate of the MetS in early adulthood was 111·6 (95 % CI 98·7, 126·3) per 10 000 person-years, with higher values in boys (210·1 (95 % CI 183·0, 241·3)), compared with girls (39·7 (95 % CI 30·2, 52·1)). In the age- and adult BMI-adjusted model, the hazard ratio of the MetS in adulthood for boys was 3·33 (95 % CI 2·08, 5·32) among MUO phenotype followed less than 6 years, 1·71 (95 % CI 1·01, 2·90) among MHO, and 2·52 (95 % CI 1·72, 3·68) among MUNW. All associations were attenuated in girls except for MUO phenotype followed less than 6 years (5·72 (95 % CI 2·14, 15·3)). In conclusion, MUNW and MHO phenotypes in boys, but not in girls, and MUO phenotype in both sexes with less than 6 years of follow-up increased the risk of adult MetS compared with MHNW. It seems that lack of obesity at least in boys does not protect them from MetS development in adulthood.