How much is a cat supposed to eat

Elvis is 17.8 lb as of today and the vet wants Elvis to get down to about 12 or 13 lb before she's going to do the dental work. Elvis eats Fancy feast turkey and giblets pate and liver and chicken pate. I thought a few weeks ago that he was losing too quick but he hasn't really budged since the first weight which was 17.8 lb but then he lost 8 oz in a couple of weeks but now he's jump backed up to 17.8. Elvis is no longer getting insulin because his numbers have been in the 70's on a human meter for quite some time now about 3-4 months. He has gone lower like in the high 60s but only a few times in the last 3 to 4 months. Mostly what I'm wondering is how much food do your cats eat and which one of your cats is overweight and how much do you feed them. I haven't posted on my sheets because I got a new phone and everything just got gone and I've been going through a really hard time with and ex-roommate deciding to stay in the old apartment and accruing over $2,000 and then the old apartment saying that I'm responsible for that money when I wasn't even there but that's all over now since today because I went to court today and I won the case! So about how much to feed Elvis?? I called my vet today about a half an hour ago and they said that they were going to get back to me but it might not be until tomorrow. Elvis is funny sometimes he seems like he's hungry and he wants more food other times I can barely get a little more than a can in him and he still seems fine but I managed to get the two cans in half but then again lately I haven't been watching him that closely and I think he's been eating a lot more than that. It's just that I've been so consumed with issues that I've been going on with my past roommate but that won't be happening anymore since today like I said oh, I won the case.

 

Dr. Pierson's list says the turkey and giblets is 96 calories and the liver and chicken is 89 calories. She also has a page on How Much Should I Feed, that describe what to feed per a certain weight, and also how to slowly and safely take weight off. One formula is Required calories per day = [13.6 X optimal lean body weight in pounds] + 70. If his optimal body weight is 13 lbs, that would be approximately 246 calories. So less than 3 cans. But Elvis weighs more than that and you want to have a safe rate of weight loss. You should be weighing him regularly and making sure he's not losing weight too fast.