Correlation Analysis Between Obesity Body Type Phenotype、Obesity Metabolic Phenotype And Pubertal Timing In Adolescents Aged 12-13

Objective:The pubertal timing refers to the relatively early,timely or delayed pubertal development of an individual in the context of a reference population or when compared to a norm,and is distinct from the clinically diagnosed pathological"precocious puberty"and"delayed pubertal development The term"pubertal timing"is used from a population health perspective to describe the differences in the initiation of pubertal development among individuals due to a combination of internal and external factors such as genetics and environment.Such differences are associated with many factors such as genetic,nutritional,environmental,stress and endocrine factors,among which obesity is considered to be an important factor that may affect pubertal initiation chronotopically.However,most previous studies on the relationship between obesity and pubertal timing in adolescents have used body mass index（BMI）alone as a measure of obesity,which ignores the important role of body fat distribution and metabolic phenotype and has some limitations.In this study,we investigated the age group of 12-13 years old adolescents at the end of puberty initiation phase,and investigated the association between different obesity states and their pubertal timing in Fuxin City,Liaoning Province,by combining the body type phenotype and metabolic phenotype of obesity.Methods:A total of 603 adolescents aged 12-13 years in nine junior high schools in Fuxin city,Liaoning Province,were selected as the study subjects using a randomized whole-group sampling method in November 2021.Demographic characteristics,body surface measurements,and metabolism-related indicators were collected through physical examination,questionnaires,and blood biochemical tests;the Pubertal Development Scale（PDS）was used to calculate the pubertal timing score of the study subjects.Pubertal Development Scale（PDS）was used to calculate the pubertal timing score of the study subjects.The data were statistically analyzed using SPSS 26.0 software.First,the basic demographic information,pubertal timing score,obesity body type phenotype and metabolic phenotype were analyzed descriptively;P₂₅,P₅₀ and P₇₅ of the PDS scores stratified by age and gender were used as the cut-off criteria（norm）to evaluate the relative level of pubertal timing score in this survey population.Finally,a multivariate analysis was performed using unconditional logistic regression with obesity body type phenotype and obesity metabolic phenotype as independent variables and whether pubertal timing was early or not as dependent variables.The relative risk（OR）and 95%confidence interval（95%CI）were calculated after gradually adjusting for confounding factors.P<0.05indicates that the difference was statistically significant.Results:1.A total of 603 subjects were included in the study,of which 37（12.80%）male students were in the early pubertal timing and 54（17.20%）female students were in the early pubertal timing.In the obesity body type phenotype,mixed obesity accounted for13.69%in the female group and 20.76%in the male group.In the obesity metabolic phenotype,metabolically healthy obesity（MHO）accounted for 7.96%in female group and 12.80%in male group.2.The chi-square test for the association between obesity body type phenotype and pubertal timing showed that the detection rates of central obesity and mixed obesity were higher in the group of girls than in the group of boys;among girls,the association between obesity body type phenotype and pubertal timing was statistically significant（χ²=14.84,P<0.01）.The results of unconditional logistic regression analysis showed that the OR（95%CI）of early pubertal timing in girls with mixed obesity compared with the normal body type group was 3.63（1.68-7.84）,3.63（1.68-7.85）,and 3.46（1.58-7.57）in the three models,respectively.3.The chi-square test for the association between obesity phenotype and pubertal timing showed that the detection rates of metabolic healthy obesity（MHO）,metabolic unhealthy overweight（MUOW）,and metabolic unhealthy obesity（MUO）were higher in girls than in boys in the group with early pubertal timing;the association between obesity metabolic phenotype and early pubertal timing was statistically significant in girls（χ²=12.76,P=0.03）.P=0.03).Unconditional logistic regression analysis showed that among girls,the OR（95%CI）for early pubertal timing in girls with metabolically healthy obesity（MHO）compared to metabolic healthy normal body weight（MHNW）was 3.08（1.25-7.56）,3.08（1.25-7.57）,3.15（1.25-7.92）in the 3models,respectively.Conclusions:1.Compared with the norm population of 12-13 years old in 8 urban and rural cooperative areas in China,adolescents aged 12-13 years are generally in a state of unadvanced pubertal timing,and the detection rate of early pubertal timing was higher in girls than in boys.2.BMI and waist circumference of 12-13 years old girls were correlated with the pubertal timing;the phenotype of obesity was correlated with the pubertal timing.Compared with the normal body type group,mixed obesity was positively correlated with early pubertal timing in girls.3.No significant association was found between metabolic syndrome and pubertal timing in 12-13 years old girls;the metabolically healthy obesity is positively correlated with the earlier pubertal timing.