  We study the effect of magnetic fields up to 15 T on the heavy fermion state
of YbRh$_2$Si$_2$ via Hall effect and magnetoresistance measurements down to 50
mK. Our data show anomalies at three different characteristic fields. We
compare our data to renormalized band structure calculations through which we
identify Lifshitz transitions associated with the heavy fermion bands. The Hall
measurements indicate that the de-renormalization of the quasiparticles, {\it
i.e} the destruction of the local Kondo singlets, occurs smoothly while the
Lifshitz transitions occur within rather confined regions of the magnetic
field.
