If the HcG diet works, why would anyone have to travel to Turkey? There are plenty of places you can go here in this country to get your shot. My daughter did just that. Gained all the weight back.
Anyone can lose weight on a diet consisting of around 500 calories. It could be a diet of Twinkies as long as it was only 500 calories.
If there is a diet plan after the Hcg then why not use that diet to begin with? If it is a healthful, less calorie dense, high nutrient diet people will lose weight without hcg. I did.
I think a better guarantee, and one that would induce lots of people to come to Turkey for your treatment, would be to pay for them to take a plane, rent a hotel room and take the treatment. If it works and they keep the weight off for a year or more then they would guarantee to pay you for everything. If it works. After all, if people can trust your guarantee you certainly can trust theirs.