Abstract: Pyrrolidone carboxamides of formula (I) where R2=a group of formula (a) or (b), R5=phenyl, heteroalkyl, aryloxy, alkoxy, alkanoyl or —NR6R7 and R1, X, R3, R4, R6 and R7 have the meanings given in the description and the claims, pharmaceutically applicable acid addition salts with basic compounds of formula (I), pharmaceutically applicable salts of acid compounds of formula (I) with bases, pharmaceutically applicable esters of hydroxy- or carboxy-group containing compounds of formula (I) and hydrates and solvates thereof, inhibit the interaction of neuropeptide Y (NPY) with one of the neuropeptide receptor subtypes (NPY-Y5) and are particularly suitable for the prevention and treatment of arthritis, diabetes and especially eating disorders and obesity. The above can be produced by known methods and converted into a galenic dosage form.