sorry. late reply. although this thread was started in 2007 n i am posting my comment in 2012 but see, I have visited it in 2012 and thinking someone else can also read it so I am sharing my personal experience.
@ attractive. same is the case with me. now i am extremely busy in my business and some time use to sit 15+ hours a day (a remaining hours are sleeping time) still i lost around 5 kgs in few months.
The thing I noted i appetite (bhook). as I sit whole day long and do not do any physical activity (only mental work) so my appetite is decreased. sometimes I take meal only once a day (sometimes after 15-20 hours). This was causing my weight loss. now I tried to eat things (not junk but healthy ones like fruits etc) during my work and do not give long gaps between 1st and the next meal and found that i have started gaining the weight again. TRY IT, i am sure it works.
NOTE: I am not a doctor. This reply is based on my personal experience only.