In a method and magnetic resonance (MR) apparatus for determining time-dependent dephasing factors c of at least one fraction of a spectral component from at least two spectral components in an examination region in an examination object, the dephasing factors c are calculated directly from at least one first and one second record of MR data that have been recorded by operating an MR scanner of the apparatus with a multi-contrast sequence, using a system of equations that is based on a signal model and that describes the captured records of magnetic resonance data using parameters.