You are probably eating too little, and your metabolism has adjusted by slowing way down. Eat more - avoid carbohydrates and go for protein-based foods. No sugar. Drink a lot of water. Try to walk as much as you can. You'll see results.
Three years ago I got fed up and started working on my body. I lost a total of 90 pounds and have kept it off for 2 years. I went from 225 to 135 and I feel great. I was heavy for a long time and hated it. If anyone is trying to get thin I would highly suggest taking a look at swimming laps. It is really hard at first but it gets easier. The fat burns off like crazy and it builds muscle very fast.
As far as the diet part goes try to turn the channel during food commercials. Sounds strange but I promise it makes you hungry when you really aren't. It must be some kind of primal urge or something.