By manipulating the signals going into the system through proper diet and exercise it is indeed possible to simultaneously increase lean mass while reducing fat mass. (sciencedrivennutrition.com)
Additionally testosterone can simultaneously increase lean mass and decrease fat mass in an older population (4). (sciencedrivennutrition.com)
This protein increases the lean mass muscle by decreasing the fat accumulation in your body. (fitnesshealthzone.com)