Weight Loss Fast Without Losing Energy?

I’m wondering if anyone out there has some good ideas on how to lose weight fast (dieting combined with exercising)? I want to lose weight fast without having to take any supplements, basically a good diet and exercise program?

I’ve been on a program where I substitute nutritional shakes for 2 meals per day and I’ve lost about 15 lbs in 2 weeks. Let me know if you want the name of the program, etc. This program also includes excercise.