Should I worry he's not eating enough?

My 6 yr old male cat got out of the Vet a little over a week ago having had a blocked urinary tract. So he is now on Royal Canin urinary canned. Finally something he would eat.  He weighs 16 lbs and needs to lose several lbs and I assumed one can would be enough for him as that is about what he has been eating. One can has 142 calories. But from what I am reading on here and other places it seems he should be eating around 200 calories a day.

I have started feeding my other really obese cat the same food and don't know how much I should feed him. Also the problem is the cost of the food. Two cans a day I think I can manage but 3 or 4 is going to get out of my affordable range unless I switch my other cat to a different and cheaper brand of urinary food.

What your thoughts on what I should do and how much to feed?

Thanks

There are lots of threads here on TCS about how to help  cat to lose weight. Here are some:

http://www.thecatsite.com/t/307774/safe-weight-loss-for-cat

http://www.thecatsite.com/t/274190/how-to-achieve-weight-loss

Another good place for info is http://catinfo.org/?link=felineobesity

The general rule is to feed 20 to 25 calories per pound of ideal body weight daily  A 16 lb cat needs around 320 to 400 caloires to maintain weight. You need to slowly reduce calories over the course of several weeks or longer to help your cat to lose weight safely. Dropping down to 200 calories starting with one meal is recipie for fatty liver disease.

The prescription canned is expensive. It's often not necessary to feed it unless the cat had struvite crystals. Check with your vet first. Here's one vet's take on prscriptions diets and why they're often not needed: http://www.catinfo.org/#Prescription/Therapeutic_Diets_

For most cats, any ccommerical canned food will help with weight loss and keep the cat well hydrated. Can you feed the non-blocked cat a regular canned food? You may have to feed the cats separately so that they're not eating each other's food.

I do now feed them all separately. Now that he is on the Royal Canin SO food and I want to keep up with how much he eats. I am not restricting his food. He just doesn't seem to be that hungry. He never was one to have a big appetite anyway. So it puzzles me how he did gain the extra pounds. He stopped being as active and wanting to play.

So I am wanting to know what I should do to get him to eat more. I am worried about switching to another food. He is very finicky. He wouldn't eat the Science Diet and I know the Royal Canin has a very good reputation for helping cats with urinary problems. 

The cat that went to the Vets did have a blockage and crystals in his urine. 

The other very obese cat seems to have digestive issues. I have tried him on several canned foods and he always get loose stools. I was surprised when I have gradually been introducing this one that his stools are solid now. The reason I wanted him on Urinary food is to prevent it from happening because last week I saw him straining to urinate. I cannot afford another large Vet bill.

I appreciate the information and I will read it. My 3rd cat is 15 and I decided at his age I would just switch him to all canned Friskies and Fancy Feast. Who knows he may out live the other two. LOL

I guess I will try different things sprinkled on top of his food to try and make him eat more. He is so picky he won't eat cooked chicken as a treat.  Go figure!! 

Oh-- That is my sweet Jack's picture up there that had the blockage. 6 nights at the Vet's. I hated that!!

I do not agree with all the 'standard' guidelines on how much a cat should be feed. I think a lot needs to be taken into consideration. Especially if they are mainly sedentary indoor cats. For my 16 lb cat to start off eating 320 to 400 calories to maintain his weight would mean he would need to eat 2 1/2 cans of this food. I could never see him able to eat that much food. Those guidelines are off. I know that is a starting point but even if it is a food he loved he would not even eat 2 cans of it a day. I just don't think he gets that hungry. 

None of my cats would eat that much. Even my obese one. They get overweight for many other reasons and can manage and be healthy on less food taking their lifestyle into consideration.

I will make sure I can get him to eat as much as possible. I fault the Vets for not giving me better guidelines on how much to feed him. I was too inexperienced in feeding canned food to think to ask him not knowing the can would not give the info on the label.

I do not like to be scared into thinking they can get 'fatty liver disease' when I am trying to do the best I can. I appreciate you pointing out that information. But I am not trying to find a quick way for my cat's to lose weight.

If he's obese, then he was obviously eating at least 320 calories a day of whatever food you were feeding him. If he's barely eating 1 can of this new food, then perhaps he doesn't like it and you need to look at adding some other wet foods to his diet. I agree with the other comment, if he starts losing weight too fast you're looking at triggering other medical problems. 

There are several good quality wet foods you can add to his (and your other cats) diets to supplement the RX food. Or you could consider not using the RX food at all.