I have been on maintenance since the end of April, and I think there are a number of reasons that the "maintainers" tend to disappear:

1. Maintenance is not very exciting. The "Cinderella" part of the story is over and now it is the "happily ever after" part. Tolstoy said "All happy families resemble one another, but each unhappy family is unhappy in its own way." Unfortunately, the unhappy ones are also the more interesting.

2. Maintenance tends to be rather individualized. After low carbing since December, I have found what works for me, but I tend to have less and less faith that my personal experience is helpful to anyone else. My diet is affected by my own food preferences, metabolism, exercise level, lifestyle, age, etc.

3. Burnout. After you hang around these boards for a while, you feel like you are reading the same posts over and over: "I am soooo excited to start this diet.....", "I lost 8 pounds during Induction but since then I haven't lost anything.....", "I haven't read the book yet -- are Cheerios allowed on Induction?", "Last night I intended to have just a few potato chips, but then before I knew it....", "I lost 50 pounds on Atkins 2 years ago, but then I went back to my old way of eating and gained it all back, plus 30 pounds more..." It all gets rather discouraging.

4. And that last example brings up another unfortunate possiblity -- that the "maintainers" disappear because they are failing to "maintain."