Kefir tastes similar to yogurt. You can get it sweetened and flavored, just like yogurt, but don't do that. Get the unsweetened kind, add fruit and whatever low carb sweetener you choose (I use Stevia). I really enjoy it, it's quite a treat.

Good luck on your Carb Cycling venture. Feel free to post to my journal, there are several of us trying this now, each one doing it a little different. You have to make it work for you. Be sure and don't go nuts on the Carb up. That's VERY important, or you'll gain a lot of weight. This is just about eating enough to recharge your metabolism, then hit the lower carb again for the weight loss. I changed my sig line to more accurately reflect what I've been doing. As of today, I'm averaging 1.5 pounds a week, and it's FUN!