Abstract: The present invention relates to a device for slicing a food bar, which has a certain mass per unit length variation over its length, into food portions which, for example, each consist of N food slices and are to have a defined preset weight mM, having a blade and a support device on which the food bar lies and can be advanced in the direction of the blade, the size of this advance determining the thickness of the food slice. In addition, the invention relates to a method which has means which calculates a prediction of the mass per unit length variation of the still unsliced food bar and, based thereon, adjusts the number N and/or the thickness Ds of the food slices of the portion being sliced or the next portion to be sliced such that the actual weight approximates to the preset weight as closely as possible.