The study investigates the role of stearoyl-CoA desaturase-1 (SCD1) in lipid metabolism and obesity. Mice with a targeted disruption of the SCD1 gene exhibit reduced body adiposity, increased insulin sensitivity, and resistance to diet-induced weight gain. These effects are associated with increased energy expenditure, oxygen consumption, and up-regulation of genes involved in lipid oxidation, while down-regulation of genes involved in lipid synthesis. The SCD1-deficient mice show higher levels of plasma ketone bodies and lower levels of plasma insulin and leptin. The findings suggest that SCD1 deficiency activates lipid oxidation and reduces triglyceride synthesis and storage, contributing to the observed metabolic benefits.The study investigates the role of stearoyl-CoA desaturase-1 (SCD1) in lipid metabolism and obesity. Mice with a targeted disruption of the SCD1 gene exhibit reduced body adiposity, increased insulin sensitivity, and resistance to diet-induced weight gain. These effects are associated with increased energy expenditure, oxygen consumption, and up-regulation of genes involved in lipid oxidation, while down-regulation of genes involved in lipid synthesis. The SCD1-deficient mice show higher levels of plasma ketone bodies and lower levels of plasma insulin and leptin. The findings suggest that SCD1 deficiency activates lipid oxidation and reduces triglyceride synthesis and storage, contributing to the observed metabolic benefits.