Obesity is a growing concern in the world today. As we ponder about the many causes of this global epidemic, we are driven to look at our food and the environmental toxicants that may contribute to obesity. Deltamethrin, being a common synthetic pyrethroid used in agriculture for pest control, is the primary insecticide this study explores to connect with obesity in 3T3-L1 adipocytes. To investigate the relationship between deltamethrin and adipogenesis, various concentrations were tested, 1nM, 10nM, 100nM, 1μM, and 10μM. The result indicated that higher concentration of deltamethrin had a direct impact on fat accumulation. These experiment results indicate that deltamethrin may potentiate adipogenesis in this model. Further in vivo studies will be needed to validate these findings and confirm the effects of deltamethrin on obesity.