2 things - I think Fresca is sweetened with Asparteme, which can cause some folks to stall (and I just don't think it's the healthiest choice). Also, you want to make sure it doesn't take the place of your daily water intake.

If you are really craving something carbonated, look for diet sodas that are sweetened with Sucralose (liquid Splenda), which is much better for you.

Otherwise, sure.