A method for separating lean and/or fat from lean meat-containing material, including introducing a fluid containing particles of varying densities into a vessel. The vessel separates the fluid into low density and high density fractions. The material from the low density fraction is removed via an outlet and has a higher percentage of fat than the material introduced into the vessel. The material from the high density fraction is removed via an outlet and has a higher percentage of lean than the material introduced into the vessel. The vessel can be a cyclone having a tangential inlet and a cone-shaped body. The denser particles, which are predominantly lean, are separated, and leave via an outlet at a lower end of the vessel, while the lighter particles, which are predominantly fat, leave via an outlet at an upper end of the vessel.