Effects of psilocybin on body weight, body composition, and metabolites in male and female mice

Psilocybin increases body weight in lean male and female mice after a single intraperitoneal dose. Across the days immediately following dosing, mice receiving psilocybin were consistently heavier than saline controls, with no psilocybin effect on intake or output. Co-administration of ketanserin, a 5-HT2A/2C receptor antagonist, did not change the weight outcome. Body composition measures showed increased lean and water mass (with a stronger effect in males and a similar trend in females). Metabolic profiling also found elevated creatine kinase (CK) and aspartate aminotransferase (AST), plus increased chloride in both sexes, suggesting psilocybin may shift physiology related to water balance and organ function markers that could matter for clinical and non-clinical use.