**4. Discussion**

The primary objective of this study was to examine the relevance of various psychosocial, behavioral, and socio-environmental factors among overweight and obese youth in the US and Mexico, and to determine differences by sex. We aimed to address gaps in the current research by studying factors in distinct domains among an ethnically diverse, bi-national sample of youth. Our results support the findings of other studies in the US that have examined similar factors within these three domains [13–36]. However, as far as we know, our study is the first to explore the effects of multiple psychosocial factors, behavioral, and socio-environmental factors on overweight or obesity risk in a diverse sample of youth. By simultaneously examining all of these factors in one sample, we were able to contrast the relevance of different risk factors in a single large group, rather than across various studies, which may be difficult to compare. Additionally, to the best of our knowledge, this is one of the first studies to shed light on the association between psychosocial, behavioral, and socio-environmental factors and the presence of overweight or obesity among youth in Mexico and Latinos living in the US.

In our study, psychosocial factors, such as a higher rate of body image dissatisfaction, depressive symptoms, self-perception of overweight, and a lower weight-related QOL, were most strongly associated with overweight or obesity. These results are consistent with other studies, which found a higher prevalence of these factors among overweight or obese youth, as compared to healthy-weight youth [13–15,17,19,20]. We found that depressive symptoms are significantly associated with overweight or obesity among girls but not boys. Inconsistent gender differences have previously been reported for the relationship between depressive symptoms and obesity [14,17]. These mixed results could be attributable to variations in study design or assessment of depression [54], or due to the characteristics of the study sample. A meta-analysis of 17 studies concluded that depression is positively associated with BMI but only among females [54]. Interestingly, overweight or obese youths

in Mexico did not report more depressive symptoms than healthy-weight youths, unlike obese youths in the US, who did report more depressive symptoms than healthy-weight youths. Our findings also indicate a higher prevalence of depressive symptoms among youths in Mexico than in the US.

In terms of self-perception regarding weight, overweight or obese girls were more likely to perceive themselves as overweight or obese than boys. Similar di fferences have been observed with adolescent girls being more likely to perceive themselves as overweight or obese than boys [13]. A recent study investigated brain activation using functional magnetic resonance imaging during a body perception task in healthy males and females. They found that images of their own bodies were more salient for the female participants and concluded that females may be more vulnerable than males to conditions involving own body perception [55]. Youths in Mexico reported higher scores for all the "self-perception regarding weight categories", than youths in the US. Obese adolescents have been shown to report a lower QOL [20], which was also found in this study, with overweight or obese youth reporting significantly lower weight-related QOL than healthy-weight youth. Additionally, the weight-related QOL reported by overweight or obese youths in Mexico was lower than in the US. Notably, self-reported QOL is lower in Mexico than in the US., regardless of weight status.

The multivariate analyses indicate that obese youth were less likely to have healthy lifestyle priorities, be physically active, or eat breakfast. However, when stratified by sex, only obese females were significantly less likely to engage in physical activity. Obese and overweight youth were twice as likely to report that they exercise for weight control, compared to healthy weight youths. There are contradictory findings regarding the e ffect of physical activity by gender, with one study showing a protective e ffect only among boys [14] and another only among girls [22]. By contrast, eating breakfast has shown a consistent protective e ffect for boys and girls in various studies, across di fferent ethnic groups [14,26,27]. Our results also indicate that obese youth are less likely to consume breakfast, but when stratified by sex, this association only remained significant among obese females.

We found that obese males are less likely to report that they eat fast food, as compared to healthy-weight males. Additionally, overweight or obese youths in Mexico are less likely to eat fast food than their counterparts in the US. Previous studies have reported a negative association between eating fast food and obesity among males [27] and females [14,27]. However, other researchers have found that fast food consumption is associated with increased risk of obesity [28,29]. When relying on self-reported behaviors, there may be a higher likelihood of over reporting of socially desirable behaviors, which could explain the inverse association between fast food consumption and obesity observed in this study. Several weight control behaviors were also significantly associated with overweight and obesity in this study. There was a stronger association between weight control behaviors and BMI among males compared to females. Unhealthy weight control behaviors have been shown to predict weight gain in boys and girls [14,15,17,22]. Restrained eating was also found to be a risk factor for obesity in our study, which has previously been reported in other studies [17].

Socio-environmental factors were found to have the least significant associations with overweight or obesity. In this study, obese youth were more likely to believe that their parents are concerned about their weight, which has been previously reported in the literature [14,36]. Parental obesity has also been examined in various studies because children of obese parents may be at greater risk for obesity due to shared genetic and environmental factors [17,56]. In this study, youth who perceived their parents as heavier were more likely to be overweight or obese. Although parental health values and the availability of healthy foods at home have been reported to be significant in other studies [30,31,34,35], no significant associations were found in this study.

This study has some limitations, including that it is cross-sectional, and thus, no conclusions about the direction of causality can be made and there is a possibility of reporting bias. Participants were recruited by means of convenience sampling and might not be representative of their respective weight groups. Additionally, this is an exploratory study with a limited sample size for the participants in Mexico. Future studies should be conducted with a larger sample size that will allow for a higher significance threshold to be set for individual comparisons to compensate for the number of inferences being made. Other limitations include the specific measures that were collected using a self-reported questionnaire, a lack of validated measures, and the fact that some of the behavioral and socio-environmental indices, e.g., "healthy lifestyle priorities," "physically active," "mother/father healthy values," or "home availability of healthy foods", were created based on a limited number of variables and should be interpreted as preliminary findings. The information provided by the study participants was of a quantitative nature, so we were unable to determine the reason for some of the di fferences observed by sex or country of origin. Future studies should collect more qualitative data to investigate these di fferences. A strength of this study is that it explored the issue of overweight and obesity among an ethnically diverse group of youth in the US and Mexico, including African Americans and Latinos, who are disproportionately a ffected by obesity. Additionally, this study examined a breadth of risk factors that have not been analyzed in a comprehensive and comparative manner. Although some of the indices we created to measure eating behaviors do not have a high reliability score, the associations we observed support the expected relationships, especially when obesity is the main outcome variable. The use of indices in this study to combine various factors also allowed for a robust analysis of complex concepts.
