A honeycomb body includes leading and trailing end surfaces being mutually spaced apart in a given flow direction. Subsections are disposed in succession in the given flow direction between the end surfaces. At least some sheet-metal layers have structures forming channels therebetween extending approximately in the given flow direction through which a fluid can flow. The channels have dimensions determined by the structures of the sheet-metal layers. Each of the subsections has a different number of channels per unit of cross-sectional area and the channels have cross-sectional areas differing in each of the subsections. The sheet-metal layers include some layers being smooth or slightly structured in proportion to the dimensions of the channels, having spacings therebetween and extending from the leading to the trailing end surfaces giving the honeycomb body a monolithic form, and the sheet-metal layers include different numbers of other sheet-metal layers filling the spacings in each of the subsections.