Energetics and behavior: unrequited needs and new directions

• A growing number of studies investigate links between metabolic rate and behavior.
• A common assumption is that metabolic rate is a proxy for energetic constraints.
• We outline why this is false and provide guidelines for testing this assumption.
• We conclude by highlighting exciting directions for future work in this field.

The number of studies investigating links between among-individual differences in metabolic rate (MR) and behavior has grown dramatically in the past several years. A major and often untested assumption of these studies is that the selected measure of MR is a valid proxy for energetic constraints. We argue that without explicitly testing this assumption, observed patterns between MR and behavior are uninterpretable. We provide guidelines for evaluating how a given measure of MR relates to constraints on the acquisition or expenditure of energy. The approach we advocate will allow researchers to develop and test a priori predictions relating energy metabolism and behavior. We conclude by highlighting several exciting directions for future work in this rapidly growing field.