System and methods for collecting and preparing fat for autologous fat tissue transplantation. The system includes syringes, filtering and transferring assemblies coupled with the syringes, a centrifuge and a centrifuge insert releasably coupled with the centrifuge. Substances, including oil, fat, and denser substances, such as tumescent fluid, connective tissue, hormones and/or other non-fat substances, are harvested through a cannula into a syringe. Syringes are placed in the centrifuge insert, and subject to centrifugation. Centrifugation stratifies the substances into a top oil stratum, a middle fat stratum, and a bottom denser substance stratum. Denser substances are filtered out of the syringes during or after centrifugation. Oil is removed through an aspiration port in the plunger head of the syringe plunger. Fat is transferred from the first syringe into one or more smaller syringes through an adapter in the assembly coupled with the first syringe and the smaller syringe.