I don't think 30 day shred is the plan for someone looking to lose lots of weight - nobody's going to be losing a couple of stone just by doing 20mins of exercise a day, however much it hurts during those 20mins!
Can only speak for myself but I'll be more than happy if I continue losing 1.75lbs a week until I've completed the program, because I don't have much to lose and weight lost at that rate will be easier to keep off.
For me the main bonus' so far have been the changes in my fitness and muscle tone; I didn't tell my partner I was doing the program and after the first week he'd noticed changes in my legs and stomach - and normally I could come in the room with my knickers on my head and he wouldn't notice