The most relevant finding of the study is that data refer to a representative sample of adolescents, an initial phase of this stage of life, from a middle-income country, showing a high prevalence of body dissatisfaction. In general, gender and socioeconomic class are two factors highly associated with body dissatisfaction, but with opposite effects, depending on the type of dissatisfaction.

The results highlight prevalence of dissatisfaction due to overweight, showing a trend also found in other studies about body dissatisfaction, ranging from 44% to 83% (dissatisfaction due to overweight) and from 1.7% to 37% (dissatisfaction due to underweight) ^{21 , 28 - 29} . Some factors can influence this problem among adolescents, such as sex, anthropometric measurements, unsatisfactory meal pattern, relationship with peers (third party provocation), and social media ³⁰ .

In Brazil, however, this topic deserves attention among adolescents, since the impact of body dissatisfaction can lead to a reduction in quality of life and affect biopsychosocial aspects, such as weaknesses of mental health, eating disorders, use of anabolic steroids, and even higher chances of suicidal thoughts and ideation ^{31 - 32} . For the actions of school nurses, this information is valuable to promote adolescent care management.

Most adolescents were dissatisfied with their body due to overweight, especially girls. In agreement with these findings, Chinese adolescents also prefer smaller bodies ³³ , and other studies in Brazil have identified that while boys overestimate their body image, girls want smaller silhouettes ^{28 , 34 - 35} . Clear influence of social media on the body image was observed, generating, in most cases, dissatisfaction due to a desire to have an ideal physical standard (female thin body and male muscular body), causing fear of possible rejection and psychological distress ^{36 - 39} . With the advent of social media such as Instagram, TikTok, and Facebook, the search for perfect bodies and lifestyles has increased considerably through user profiles called fitspiration, which has put the emotional health of teenagers at risk. Studies indicate that certain profiles on these social media can lead to negative mood and decreased body satisfaction, especially among girls ⁴⁰ .

Identity construction is noticeable in adolescence, and in this period adolescents may suffer social pressure for behaviors that are dangerous to health. Then, it is important to learn about the context of vulnerability inherent to this phase, emphasizing that body dissatisfaction is more common among girls, as they are more subject to the alcohol use and smoking when they have negative images of themselves ⁴¹ .

In addition to the differences between genders, our findings point to influences of the socioeconomic status, as the chances of dissatisfaction due to underweight are lower among higher social classes, while dissatisfaction due to overweight is higher. One explanation is that lower socioeconomic classes show higher proportion of adolescents who want larger silhouettes, a fact that highlight the vulnerability of this population, particularly regarding food insecurity of families ^{42 - 43} .

Another important aspect is that eating patterns and physical activity practice are associated with body dissatisfaction as adolescents usually adopt unhealthy diets, and/or do not practice physical activity properly ⁴⁴ or skip meals ⁴⁵ . In Brazil, regardless of the region, the eating habits of adolescents mostly involve fatty foods, fast foods, foods with sugar, disregarding the importance of nutrients ⁴⁶ .

Regarding body dissatisfaction due to underweight, this study showed that adolescents who used marijuana were more likely to present this condition. Then, the literature ⁴⁷ showed that body dissatisfaction at 14 years of age in girls and boys was a predictor of marijuana use at 21. As this study analyzed cross-sectional data, marijuana cannot be considered a predictor of dissatisfaction or whether dissatisfaction led to marijuana use, but it deserves a deeper evaluation about its use and practices adopted by young people. From a pharmacological point of view, this finding could be explained by the fact that adolescents who are dissatisfied due to underweight may think that marijuana would increase their appetite and, consequently, help them gain weight. This perception would be based on the potential effect of marijuana in cases of anorexia, leading to an increase in weight ⁴⁸ .

Although the results do not indicate a significant association of alcohol and other drugs (smoking, inhalants, cocaine, and weight-loss drugs) with body dissatisfaction, the fact that 35.67% of the participants had already tried alcohol and 19.28% had episodes of binge drinking, which refers to heavy drinking in a short period (alcoholic consumption of five or more drinks over two hours), shows the importance of studies assessing the problem of alcohol use in adolescence, with care and health education initiatives that actually bring changes in the lives of adolescents. Recent studies conducted in countries such as the United States and Brazil highlight that binge drinking among male and female adolescents can have serious consequences for society and the health system, with a significant increase in hospital admission rates, involvement in traffic accidents, family violence, and other negative outcomes ^{48 - 49} .

In addition, body dissatisfaction is directly related to the consumption of alcohol in life (current and excessive consumption), as the association is common, especially regarding excessive consumption, which may be a coping mechanism or a weight change strategy ⁵ .

In relation to smoking and use of inhalants, cocaine and weight-loss drugs, the use of inhalants was more prevalent. Inhalants are central nervous system depressant substances that can be breathed in (through the mouth or nose), with volatile and flammable characteristics, commonly associated with solvents (examples: glue, nail polish, lança-perfume, acetone, loló) ⁶ . In adolescence, inhalants impair growth, affect metabolism and food intake, change food preferences and glucose metabolism and skeletal muscle adiposity, in addition to predisposing users to withdrawal syndrome, which is directly related to body image ⁵⁰ .

Then, the results of our study provide evidence to adolescent health professionals to consider body dissatisfaction as a public health problem, and it is important to promote early interventions and prevent risky behaviors. In Brazil, the culture related to alcohol consumption is so permissive in adolescence that, when combined with poor control in the sale of alcoholic drinks, requires investments in studies to assess these vulnerabilities.

The School Health Program (PSE) has an important role in Brazil; however, weaknesses are observed in the implementation of policies and programs to reduce the high rates of alcohol and drug use at early ages, reinforcing the need for specific strategies for this stage of life. It should be noted that investments in health education programs that promote the health of adolescents in the school environment help reduce smoking, episodes of heavy drinking, and drug use, such as marijuana, as observed in European countries ¹⁸ .

Study limitations include the fact that it covered only three Brazilian cities, so it should be analyzed with caution regarding the representation of the Brazilian population and its great diversity in the geographic area. In addition, the questionnaires were applied in a school environment, which can be influenced by the environment and peers, and even if teachers were not present in the classroom during data collection, it could suggest some type of recrimination or judgment in the imagination of adolescents.