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Background: Metabolic syndrome (MetS) in children is a rising health issue that is strongly associated with cardiovascular diseases and type 2 diabetes mellitus development. Low-affinity antibodies reactive to leptin and ghrelin are suggested to regulate hormone stability and function; nevertheless, the role of the leptin/ghrelin axis and antibodies reactive to both hormones in relation to MetS or its components in the pediatric population remains unknown. Methods: Fifty-eight children (7-12 years) were included and categorized according to the presence of one or more criteria for the diagnosis of MetS or according to body mass index. Body composition, biochemical variables, and metabolic risk indexes were determined. Antibodies reactive to leptin and ghrelin were quantified by an in-house enzyme-linked immunosorbent assay test. Ratios of leptin/ghrelin hormones and anti-leptin/anti-ghrelin immune complexes were obtained. Results: The biochemical variables glucose (P = 0.0009), insulin (P = 0.0001), leptin (P = 0.0036), HOMA-IR (homeostatic model assessment for insulin resistance) (P < 0.0001), and plasma atherogenic index (P < 0.0001) were significantly higher in children with two or three components of MetS (MetS 2-3) in comparison to children with none or one component (MetS 0-1). Ratios of leptin/ghrelin (P = 0.0307) and anti-leptin/anti-ghrelin immune complexes (P = 0.0338) were higher in MetS 2-3 group versus MetS 0-1 group. In MetS 2-3 group, both insulin (r = 0.4361, P = 0.0293) and HOMA-IR (r = 0.4761, P = 0.0161) were positively correlated with the leptin/ghrelin hormone ratio. Conclusions: The higher leptin/ghrelin hormone ratio scores observed in MetS 2-3 group, along with their correlation with insulin levels and HOMA-IR, highlight the role of leptin and ghrelin on insulin sensitivity and metabolic regulation. An increased ratio of anti-leptin/anti-ghrelin immune complexes suggests affinity changes in these antibodies that may lead to alterations in hormone function.

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Resumen La obesidad constituye un problema de salud a nivel mundial y una de las principales causas de las enfermedades crónicas. Existen diversos factores que influyen en el comportamiento alimentario y la obesidad, los cuales pueden ser genéticos, fisiológicos, nutricionales, psicológicos o socioculturales. En las últimas décadas, el cambio en el estilo de vida ha provocado patrones de alimentación inadecuados, aunados a disminución en el gasto energético. En esta revisión se describen los principales factores fisiológicos, nutricionales y psicológicos que intervienen en la ingesta energética y el comportamiento alimentario, y cómo es que estos pueden −vía la regulación del apetito y del peso corporal− influir en el desarrollo de la obesidad. La neuropsicología de la recompensa de los alimentos, de las preferencias, de la elección y del comportamiento alimentario son aspectos aún no comprendidos. Investigaciones futuras tienen que enfocarse en dilucidar las vías involucradas en los aspectos gratificantes de los alimentos y, como una alternativa para controlar la obesidad, replicar esta experiencia con alimentos más saludables. Sin embargo, la comprensión del vínculo entre alimentación, ingesta energética y regulación del peso corporal solo se logrará a través del trabajo multidisciplinario.

Abstract Obesity is a global health problem and one of the main causes of chronic diseases. There are several factors that influence eating behavior and obesity, which can be genetic, physiological, nutritional, psychological or sociocultural. In recent decades, the change in lifestyle has caused inadequate eating patterns, coupled with a decrease in energy expenditure. This review describes the main physiological, nutritional and psychological factors that intervene in energy intake and eating behavior and how they can -by regulating appetite and body weight- influence the development of obesity. The neuropsychology of food reward, preferences, choice and eating behavior are aspects not yet understood. Future research needs to focus on elucidating the pathways involved in the rewarding aspects of food and, as an alternative to control obesity, replicate this experience with healthier foods. However, understanding the link between food, energy intake and body weight regulation will only be achieved through multidisciplinary work.