If you've definitely stayed OP 100%, it's water weight. It'll drop off.
When I got off BC (also after 10 years on) in June '11, I gained a smidge of water weight afterward. For about 3 months after I got off it, I had significantly more food cravings and felt generally hungrier. I'm quite sure that, water weight aside, this is the reason why those women gained weight. Most people (not those on 3FC!
) don't accurately track their food/calorie intake; when they say they "haven't changed their diet," they may really believe this, but it's not true.
Echoing
Brid, the claims of up to 60 pounds gained in 3 months are bizarre. People lie and exaggerate. Maybe this has happened to some rare individual, but I find it quite unbelievable that this happens on any widespread basis.
After 3 or 4 months, the cravings and hunger went away. I get far less of both now than I did during the 10 years on the Pill. The couple of pounds of water weight mysteriously dropped off eventually, and I didn't gain any more than that. Just keep on track!