Based on my DEXA scan of 18% body fat and mass being 65kg (last I measured), it gives me around 53.3kg of lean mass or so. That means if I want to reach 12% body fat my ideal weight has to be 61kg. I haven't ever been able to breach 63kg, and even then I'm pretty sure that was lack of shit/pee/water that caused the fluctuation.

@Animeniax: after you reach your target, you maintain it. The idea of a journey sounds good and has its merits, but at the same time not everybody wants to bulk or lose weight indefinitely.