The magnetization level of macromolecular protons (MPs) affects that of water protons through magnetization transfer, a phenomenon that represents a confounding factor in quantitative MRI. Here we investigated whether MP spectral lineshape can be sufficiently accurately modelled by a single Lorentzian, which would facilitate estimating MP magnetization and saturation levels from Bloch simulations and a 2-pool MT model. We compared simulated effects of 10 different composite MT pulses and experimental results from 11 healthy volunteers at 7T. Results demonstrate a good fitting to the observed water signal evolution. Deviation of the simulated initial MP saturation from calculated levels was observed, indicating potentially unaccounted factors such as inhomogeneous MT effects.