I'm drinking a flavored coffee as I write this. I use heavy cream and Splenda in it. I also drink diet soda constantly. The coffee and the soda that I drink are all decaf though. The soda is Diet Rite, which is sweetened with Splenda. I thought that we were just suppose to give up caffeine. I lost 20 lbs. the first month I was on Atkins and I never gave up coffee or soda. So, do what you want and see how it affects your weight loss.