Abstract
Abstract
Obesity and metabolic alterations related to excess adiposity constitute important public health concerns resulting from the interaction of environmental, behavioral, metabolic, and genetic factors. In this context, the regulation of food intake and energy balance involves neuroendocrine mechanisms in which leptin and ghrelin play complementary roles. Leptin, produced mainly by adipose tissue, contributes to the signaling of energy availability and satiety, whereas ghrelin, predominantly secreted by the stomach, stimulates appetite and participates in energy regulation. Genetic variants related to appetite control and metabolism may contribute to individual differences in adiposity and obesity risk. Among the most extensively studied are rs9939609 in the FTO gene, rs17782313 near the MC4R gene, and rs1801260 in the CLOCK gene. These variants are involved, respectively, in mechanisms related to energy balance and eating behavior, central regulation of food intake, and circadian rhythm regulation, potentially influencing metabolic and hormonal processes. Although these polymorphisms have been investigated in relation to obesity and metabolic characteristics, evidence regarding their association with leptin and ghrelin concentrations remains scattered and potentially inconsistent. Synthesizing this evidence may help clarify the relationship between genetic variants and hormonal mechanisms involved in appetite regulation. Therefore, this systematic review is justified by the need to critically integrate the available evidence on the association of the rs9939609, rs17782313, and rs1801260 variants with leptin and ghrelin concentrations in adults, identifying potential sources of heterogeneity and contributing to a broader understanding of the biological mechanisms underlying obesity.