I have never heard of it, but from looking at the website, it looks a lot like the "easy weight loss" garbage that's advertised for humans that says we can eat what we want and still lose weight. There are no quick fixes for us, and I'm sure that pertains to our furkids too.
Also, putting a cat on a diet needs to be very carefully monitored. It is dangerous for cats to lose weight too quickly because this predisposes them to the development of hepatic lipidosis, a potentially fatal liver disease whereby fat is deposited within the liver as a result of a change in metabolism during fasting. A gradual, steady decrease in bodyweight is ideal; it may take up to a year for a severely overweight cat to reach its ideal body condition.