I have been on the zone diet for about 4 weeks now and am having good success. I like the diet because if I eat what they tell me to and keep my meals balanced 40/30/30, I don't feel hungry ever and the weight comes off. I have to admit that the meals themselves are n't that exciting. I need to invest in a Zone cookbook or something. I've been following the eDiets Zone plan (Glycemic Impact).
I've been losing 1-2 pounds a week and I exercise almost every day. So if you're losing a pound a week and NOT exercising, that's pretty good.
If you want to lose more weight, look at how many calories you are eating. Calories out has to be more than calories in or you won't lose weight, so try decreasing your calories by 100-200/day (but don't go below 1200/day!). You could do this as well by starting to exercise, even if it's just walking 4-5 times a week. You shouldn't need any more calories even if you start exercising.
Hope this helps!