The Sex and the City star explained that she struggled to shed 20 pounds.
She told Access Hollywood: "I found it so easy to put it on and so terribly hard to take it off... Eat Right For Your Blood Type is a great diet and I've used that before.
"I'm the kind of dieter, I can't have a little tiny bit of it because I want it all, so it is all or nothing... So that diet was great."
The actress was required to put on weight for her role in Meet Monica Velour where she played an older porn star turned stripper and insisted that it was very difficult to slim down.
She commented: "It was painstaking - exercising a lot and being on the diet and not snacking. My appetite did shrink and I did lose the weight."
Cattrall previously admitted that she struggles to continue dieting in order to maintain her figure as she gets older.