The present invention relates to a process for producing a water-absorbing polymer, comprising the process steps of (i) mixing (α1) 0.1 to 99.999% by weight of polymerizable, ethylenically unsaturated monomers containing acid groups, or salts thereof, (α2) 0 to 70% by weight of polymerized, ethylenically unsaturated monomers copolymerizable with (α1), (α3) 0.001 to 10% by weight of one or more crosslinkers, where the sum of the weights (α1) to (α3) is 100% by weight, (ii) free-radical polymerization with crosslinking to form a water-insoluble, aqueous untreated hydrogel polymer, (iii) drying the hydrogel polymer, (iv) grinding and sieving the water-absorbing polymer to size, wherein the aqueous monomer solution, is admixed with 0.01 to 5% by weight of at least one surfactant and optionally 0.01 to 5% by weight of a blowing agent having a particle size of 10 μm to 900 μm, based on the water-absorbing polymer.