Found this article, it's about implications for athletes, but I would think conclusions would be the same for the rest of us. Suggests that periodic "re-feeding" and/or "reverse dieting" may help to prevent metabolic adaptation (which leads to plateaus). If I hit a REAL plateau, I'll try a short-term re-feed. But I'm also going to work on increasing my exercise in a step-wise fashion. The article didn't discuss that, but of course athletes already have very high exercise rates...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943438/