A low-cost trait: sebum secretion in mammalian energy budgets

This manuscript addresses a fundamental but previously unquantified aspect of mammalian physiology: the energetic cost of a continuous peripheral lipid export pathway. By integrating dermatological measurements with whole-body energy budgets across species, it reveals that sebum represents a continuous yet energetically trivial metabolic flux. This finding reframes sebum as a low-cost, evolutionarily permissive trait, helps resolve apparent paradoxes between hair coverage and lipid secretion, and provides a quantitative framework that is timely given renewed interest in skin biology, barrier energetics, and comparative metabolism.