The production of heat by metabolic processes. In the context of weight management, thermogenesis refers specifically to energy expenditure beyond basal metabolic rate and physical activity—the body burning calories to generate heat rather than storing them as fat.

Brown adipose tissue (brown fat) is the primary site of non-shivering thermogenesis, converting chemical energy directly into heat via uncoupling protein 1 (UCP1). Some peptide compounds interact with thermogenic pathways: AOD-9604 was investigated for increasing energy expenditure, and MOTS-c activates AMPK, which can influence thermogenic brown fat activity. However, the clinical significance of peptide-induced thermogenesis for weight loss in humans remains unestablished—the caloric impact of increased thermogenesis is typically small compared to changes in appetite and food intake.