I had to give up diet drinks altogether; discovered after a while that the sweet taste was setting up an insulin reaction that made me want to keep eating after I was full. Now I drink selzer water for the bubbles and taste when I get tired of regular water.

Sounds like you might be drinking a lot of caffeine, and that can affect your appetite. Atkins says no caffeine, which can be brutal on a high-consumer. I ignored him on this, but I'm only drinking one cup of coffee so I can rationalize it.

YMMV.