The metabolic mind: A role for leptin and ghrelin in affect and social cognition

Leptin and ghrelin are metabolic hormones central to energy regulation in the body. Theories of allostasis suggest that metabolism could matter for more than just food intake and weight regulation but also ultimately for psychological processes, such as affect and social cognition. Allostasis is the process by which the brain monitors ongoing physiological states and, in turn, regulates physiology based on expectations about how a given situation will impact the self. Motivated by this allostatic perspective, we argue that leptin and ghrelin may be influenced by and even contribute to psychological processes such as affect and social cognition. Specifically, we review literature suggesting that leptin and ghrelin may be sensitive to social affective signals and related contexts (e.g., social status, and social threat vs. support), given that these signals and contexts may represent access to tangible physical and psychological resources that support allostasis and metabolic needs. We then review literature showing that leptin, ghrelin, and associated metabolic states may feed into the construction of social affective states and behaviors (e.g., emotion and risk taking), in order to motivate behaviors in line with allostatic needs. We close by offering guidelines for researchers interested in contributing to this emerging field and highlight opportunities for future research. We believe that leptin and ghrelin offer exciting new directions for social and affective scientists interested in linking the mind, brain, and body.