I've had this same reaction with the bars, and have decided once and for all that the bars are out (until I switch to the modified plan in three months). My strong cravings for the bars didn't get out of hand until Aunt Flo came into town last week, but after eating two bars a day, twice, I'm not taking any chances in the future and have just eliminated them altogether.
It sounds like your cravings aren't necessarily physiological but psychological--so eating the soup is not doing anything to your body, per se, but more so to your brain, tapping into the part of us that enjoys eating. If you find yourself craving the soup so strongly, where you feel it might eventually prompt you to eat other food, then I would nix it. I decided to not eat my beloved chili and cream of broccoli soup for a couple of weeks, either. The soups don't create cravings/obsession in me like the bars do, and I'm fine with one soup a day. But since I have noticed myself becoming more attached to the "food" part of my full fast lately, I'm just going to shake it for a bit to break this.
That's just my take on it. Again, if you feel even remotely like this will hinder your progress, then nix it . Don't take a chance of falling off--you are doing so well
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Take care,
Sheryl