A Case of the.... Lost - Episode 4-5

I consider myself relatively wise regarding the inner workings of how television shows are filmed, but there’s something about Lost that I always had trouble with, and it’s especially true with Desmond-centric episodes: How on earth is he filmed with long hair and a heavy beard in the present timeline, and clean shaven with close cut hair in the past? The easy answer is a wig and fake beard (like everybody’s favorite deceased Other), but a quick WireImage search on Henry Ian Cusick (who portrays everybody’s favorite world racer) reveals that, in reality, he does indeed have long hair and a beard. I suppose the next logical answer is that they film all of Desmond’s long hair/beard scenes, and then later have him shave and cut his hair to film his flashback scenes. But that seems really inefficient. Can anybody fill me in on the actual answer? Not even theories….I want THE answer. And cite your source.

Now, onto the episode…

http://primetimepulse.insidepulse.com/2008/03/03/a-case-of-the-lost-episode-4-5/#more-73760