Weight loss tips????

I'm looking for some weight loss tricks. My cat was very athletic when I got her. Now she's a year and a half...and almost 12 pounds. I feed her once a day, and encourage her to be active. She knows she is a little chunky, it's hard for her to sit on her big belly, so she lays on her back instead. I think 1 or 2 pounds off would be a huge improvement. Any tips or advice are welcome!