  We study asymptotically Lifshitz spacetimes and the constraints on flows
between Lifshitz fixed points imposed by the null energy condition. In contrast
with the relativistic holographic c-theorem, where the effective AdS radius, L,
is monotonically decreasing in the IR, for Lifshitz backgrounds we find that
both L and z may flow in either direction. We demonstrate this with several
numerical examples in a phenomenological model with a massive gauge field
coupled to a real scalar.
