I've found the greatest success in limiting carbs and calories. Currently I'm following weight watchers and trying to focus on more "natural carbs" - like fruits and veggies than processed junk. Counting the points helps me limit my calories too.
I've lost 5 pounds in as many weeks, which is a good rate of weight loss. Of course I'd like it to be more but as someone with diabetes, it just takes a little longer for our special selves.
