  We compute the collisional energy loss of an {energetic} massive fermion
crossing a chiral plasma at finite temperature characterized by an imbalance
between the populations of left-handed and right-handed fermions. We find a new
contribution to the energy loss which is proportional to the helicity of the
test fermion and depends on the amount of chiral imbalance in the plasma. We
then compute the difference between the energy loss of a fermion with the two
opposite helicities, to assess whether this could be used to quantify the
chiral imbalance in the plasma. We find that the leading contribution to these
helicity-dependent energy loss contributions comes from the exchange of hard
photons (or gluons for QCD) with the medium constituents, and in some scenarios
can become comparable to the leading-order result for a plasma without any
chiral imbalance. We also evaluate the contribution arising from soft photon
exchange, which is a subleading effect, and requires regularization. We
illustrate how dimensional regularization is a well suited prescription to be
applied to these energy loss computations.
