From what I've read all over the web on the subject, it definitely is a YMMV thing (Your Mileage May Vary). On the subject of caffeine, the overwhelming evidence seems to be that it has little effect on successful weight loss, except for sensitive individuals. With diet soda pop, whatever the type - cola, ginger ale, etc - it appears the culprits may be the citric and/or phosphoric acid, NOT the caffeine. And aspartame/nutrasweet can be a staller for some.

For most lowcarbers, it seems that consuming diet colas in moderation is not a huge problem; switching to caffeine or sodium-free is certainly an option if you're concerned. My thought is ... if diet coke or pepsi or whatever is something you really enjoy, and having a glass or can of this will help stave off the craving for something else with tons of sugar in it ... my vote goes for the diet pop .. ... On the other hand, if you're sticking pretty close to your lowcarb plan, and you hit a stall ... maybe cut out the diet drinks for a couple weeks to see if things get moving again.

Best of luck; keep us posted

Doreen