Depends on how quick? I am on the calorie shifting diet progarm and it does work, but you do have to be very sticked about the food you eat and no cheating! :)
I found that my first two days of the diets were very hard, but after that it was walk in the park. You are only on a diet for 11 days, and than you have 3 day cheating period and you can go back on a diet. You can lose up to 9 pounds in 11 days, I so far managed to get close to it (but I did cheat on my day two) so maybe that is why.
Overall, the diet is very healthy, you will eat a lot of vegetables, and meat such as chicken breast, but you do have to keep at it for it to work! But every 11 days, your diet plan changes and it is generated electronic, it is made to shift the calories every 14 days. The food you eat is going to be the food you like!