I lost 30 pounds this summer by not drinking Coke, eating more healthily (is that a word?) and riding a bike 32 kms. (20 miles) every day for 10 weeks. I started out taking 2-1/2 hours, and got it down to 1-1/2 hours to do the same 32 km. route. I think the key is to realize it is a life style change, not a simple and quick way to looking like Kai. I also agree with the advice not to take supplements. If you eat right, you don't need them. They are very expensive, and at best do nothing for you. At worst, they could damage you.
Drink lots and lots and lots of water. Then drink more.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)