Speaking for myself, I topped out around 270 several years ago, at which point I sort of freaked out and dropped down to about 220. Over the next several years, I sort of fluctuated in a range between 220-230, never really going outside it either way. A few months ago, I just sort of made a decision that I was going to drop whatever else I felt like dropping until I was satisfied.
So, I completely changed my dieting habits and eat about 95% health food. Most nights I don't get home from work til between 1-2am, so I generally sleep til about noon. A typical day for me from then on is a protein shake, followed by the gym. I eat my main meal in the late afternoon before I go to work, which is always chicken or some sort of fish, with spinach and brown rice. I usually bring a couple of turkey sandwiches on wheat bread to work with me. When I get home, I generally have a leftover piece of chicken or fish, and maybe a couple pieces of fruit. Other than that, if I happen to get a craving, I indulge it, don't engage in any guilt over it, and am back to normal as soon as it's done (just last night I had a post-bar cheeseburger ).
The other thing I did was implement a regular exercise routine of weights 2 or 3 times a week, plus cardio once or twice a week. That's what really makes the difference between losing weight, and losing fat while maintaining your muscle. The former is relatively easy, the latter takes a bit more work. Anyway, the end result of all this is that I'm currently going just under 190 (from around 215 when I started), with my body fat percentage at around 12% (from about 20%). I've decided that I want to get to 8%, which, if I keep maintaining my muscle, should put me at around 180. When I get to that point, I'll decide if I want to actively start building more muscle. As it is, I'm starting to see muscle tone for basically the first time in my life. It ain't a bad feeling.
Now, some might be reading this and saying 'Strider, you asshole, you're making it sound like you just flipped a switch and changed your habits overnight'. I wish I could give some sort of elucidation as to how I did this, but I really don't know. I just sort of decided I was going to do it, and, yeah, I basically changed my entire diet and fitness routine more or less overnight without thinking twice about it. And somewhere along the line, I've actually transitioned into a health nut as opposed to someone who was just doing this temporarily. I seriously can't see having any other routine than the one I do now.