I've been using the tools at
http://www.fitwatch.com, which I subscribe to as well to track my food and build recipes, etc., and I am using the "extreme fat loss" column on the zigzag calculator that's available in several places on the web -- just google it, it all seems to be the same tool.
I've been losing 5 lbs per month this way. The zigzagging helped tremendously when I started to plateau. I figured out it was for real when, after a week an a half of taking my calories down to maintainence minus 500, and limiting carbs to 40% of my diet, my body freaked out and I binged on 3250 calories in one day... and promptly lost 3 pounds.
Then I started paying attention to zigzagging, and took my calories back up to maintainence minus 15%, and let go of the minus 500 and carb restriction ideas. My body is way happy again, and still losing steadily. :-)