I am 20 pounds overweight, but i am pretty quick and strong. i am wondering if i can lose atleast half of that in a very short time. thanks!

To lose: 20 pounds you have to burn off 70,000 calories that you don't eat. That takes a long time. A good steady weight loss of 1/2 to one pound/week is fantastic.

Just be sensible.: The real key to weight loss is to just watch the size of your portions at meals, eat healthy, and exercise regularly. There's no radical diet or exercise plan or pill that will magically give you meaningful and sustained weight loss. The ol' fashioned way is still be best way to lose weight for the long term. Two pounds per week is a prudent rate of loss.