Truely beautiful cats, I love your black Girls do put on a lot of weight after being spayed but they do naturally lose it after a good few months as their hormones start to settle down.

Although she is on an obesity diet, dry has a lot of carbs in it, empty calories. Will she eat fresh meat. You could try substituting a couple of meals of lean meat, boiled chicken - no skin, cooked or raw if she will eat it. A good low fat high quality protein meal should fill her up a bit more. If she will eat raw then chunks of lean beef or lamb that she really has to chew on would make a meal time last longer for her, and may make her feel more satisfied.