The prevalence of metabolic syndrome in obese children and adolescents has increased worldwide. Obese children have higher abdominal fat, which is associated with hyperinsulinism and cardiometabolic alterations such as low HDLc, increased triglycerides and LDLc, and increased blood pressure, resulting in increased risk for type 2 diabetes and cardiovascular diseases [6, 9, 16–19].
Our results are from a transversal study performed at initial clinical and nutritional evaluation of adolescents when they spontaneously signed up for consultation at the Adolescent Medicine Outpatient Clinic, which sees adolescents between 10 and 20 years of age and where consultations are arranged in advance [where the only limiting factor is the availability of professionals in this area to provide consultations]. In the study period, 321 adolescents between 10 and 16 years of age who presented with excess weight were included in the sample. We stress again that the participants are from a sample constructed for convenience, however those making up the sample were sequentially introduced, a measure incorporated into the treatment provided at the outpatient clinic. Therefore our results should be used with caution in overweight, obese, and extremely obese adolescents from other populations.
We found a high prevalence of overweight, obese, and extremely obese adolescents, together with a high prevalence of cardiometabolic risk factors, such as dyslipidemia and blood pressure alterations, in these individuals, potentially contributing to MS onset at early ages. The high prevalence of obesity found in this study clearly reflects the process of nutritional transition occurring in Brazil, through which undernutrition is replaced by obesity [20, 21]. In a retrospective study of adolescents who also attended this clinic between 1988 and 1996, the authors showed that overweight and obesity doubled in females and more than tripled in males during this period . Another study reported that the percentage of individuals who presented MS factors almost doubled over a ten-year period 
Anthropometric measurements, especially abdominal circumference, are crucial for MS diagnosis. In addition, measurements of serum lipid fractions, fasting glucose values, and blood pressure in susceptible or overweight individuals are also important. Evaluation of fasting insulin has been highlighted, given that a strong association between basal hyperinsulinemia, blood pressure alterations, and dyslipidemia has been demonstrated. Furthermore, insulin resistance has been indicated as the physiological basis for MS [23, 24], since it precedes diabetes, anticipating insulin secretion failure . It has also been suggested that hyperinsulinemia precedes the appearance of MS in infancy and adolescence, possibly explaining the association between obesity and the observed vascular dysfunctions .
In this study, an abnormal abdominal circumference was the most prevalent anthropometric parameter for both male and female adolescents, being more frequent in extremely obese females (96.6%) than in extremely obese males (76%). Of the 321 adolescents analyzed, 31% had at least one cardiometabolic risk factor, 26% had at least two, and 25% did not present any of the risk factors. The prevalence of three or more risk factors was higher in the extremely obese groups of both genders, at 41.7% in females and 30.6% in males. A previous study performed in Bogalusa, USA, found that 26% of adolescents had at least one risk factor and 4% had at least three risk factors. In extremely obese adolescents, 34% of females and 32% of males had at least three risk factors .
We also observed that the metabolic abnormalities were more significant and frequent in individuals with higher BMI values, specifically in obese and extremely obese adolescents compared to those considered overweight. Altered HDLc was the most frequent of the cardiometabolic parameters, followed by abnormal blood pressure and triglycerides levels. When the metabolic abnormalities were analyzed in groups stratified by gender, we observed an increased prevalence in females. Approximately 50% of extremely obese females had low HDLc levels and 30% had increased triglycerides. In males, HDLc was the most frequent (30%) altered cardiometabolic parameter, followed by increased blood pressure (21%), the latter being the most prevalent abnormality found in extremely obese males, with a frequency of 36%.
When analyzing the variables associated with insulin resistance, we found significant differences in adolescent female groups for all criteria. A higher percentage of girls (75%), than boys (55%), presented insulin resistance according to FGI values. Moran et al.; Barja et al.; Jeffery et al. support our findings, as they stress the influence of sexual dimorphism, which results from the earlier appearance of secondary sexual characteristics in girls compared to boys, external biological expression modulated by hormonal ebullience belonging to the puberty years. For Jeffery et al., HOMA-IR levels were higher in girls than boys at all evaluated ages, from 7 to 14 years, even after adjustments, presenting their peak when the adolescents were found in Tanner stage 3 and 4, moments associated with peak height velocity . Regardless of gender, the extremely obese group presented the highest degree of insulin resistance. Our data differ from a previous study in which no significant differences in fasting insulin values were observed among eutrophic, overweight, and obese groups , possibly because analyses were conducted according to gender. We would like to emphasize that the cutoff points used in this study for anthropometric and biochemical variables and for insulin resistance are those recommended by IDF  for the studied age band, found in related international scientific literature [13–15], stressing that specific values for the Brazilian adolescent population are still not available. We believe that these values will soon be available as a large population study called the ERICA study (Study of Cardiovascular Risks in Adolescents) is being developed.
Considering the IDF criteria for MS diagnosis , we showed that around 18% of the adolescents analyzed presented the syndrome, which was more prevalent in extremely obese individuals, especially females.
A study in India with 2640 adolescents of both genders produced similar results; in eutrophic and overweight/obese adolescents, abnormalities in triglycerides, HDLc, basal insulin, and insulin resistance levels evaluated by HOMA-IR were higher in females. HOMA-IR values were much higher in individuals presenting parameters indicative of MS. Altered cardiometabolic parameters, of which reduced HDLc and increased triglycerides were the most common, were more frequent in overweight adolescents. Increased abdominal circumference was found in approximately 86% of overweight/obese adolescents .
The transversal approach used in this study raises the question of instability in metabolic syndrome diagnosis. Considering the intense growth and puberty changes, a longitudinal follow-up of our study individuals would be necessary. Nevertheless, studies have shown that 85% of obese individuals in this age group remain obese in adulthood [4, 9] and many are diagnosed with MS. Even though some of these patients do not present the syndrome in the following years, its diagnosis during childhood and adolescence reinforces the importance of implementing effective treatment at an early age. Preventive measures aimed at reducing the incidence of obesity and its consequences at younger ages should also be adopted.