With a large-area field electron emitter, when an individual post-like emitter is sufficiently resistive, and current through it sufficiently large, then voltage loss occurs along it. This conference presentation provides a simple analytical and conceptual demonstration that this voltage loss is directly and inextricably linked to a reduction in the field enhancement factor (FEF) at the post apex, and also argues that progressive increase in voltage loss will lead to “saturation” in Fowler-Nordheim plots. There are other possible causes of saturation, such as series resistance effects, but it is argued that — contrary to previous thinking — FEF-reduction effects may be the commonest cause of saturation. Joint experimental observation of saturation effects and relatively low voltage deficits (< 20 V, say) could be a strong indicator that the saturation is being caused by FEF reduction.