No, for that the humans have to be trained.  ;)

Basically, if you want different diets for each cat in a multi-cat
household you will need to stop free-feeding.

It may be - or you can feed them in separate places, or... in my cats'
cases, I've let the other cat(s) go ahead & also eat the "light" food.  When
feeding the "light" foods & limiting one cat's consumption, I've also fed
another regular - &/or "Senior" - food(s) for the other cat(s), so they -
the ones not on a diet - wound up eating both kinds of food.

The only things I think you really need to be careful about are: if you feed
a "Light" food, but don't limit the fat cat's intake he still won't lose
weight.  On the other side of the coin, you have to make sure that he loses
weight really slowly, so that it doesn't affect his liver adversely.

Cathy

I don't think it is possible to train them to do this--happily,
you have doors on some of the rooms of your house. You can
work the rest out. :)

Not necessarily.  Weight loss diets usually contain more fiber and less fat
than maintenance diets which also makes them less palatable.  Given the
choice, most cats would rather eat a maintenance diet.  I think the problem
would be keeping the overweight cat away from the maintenance diet rather
than keeping the normal cat away from the weight loss diet.

If your cats are used to free feeding, feeding them seperately will be a bit
of a problem.  However, there are a few tricks you can try.

1. Put the normal cat's food in high place that's difficult to reach and
small enough so just one cat can get to it at a time -- or in a place where
the normal cat would have to jump a few feet to get to.

2. If the overweight cat is a lot larger than the normal cat, cut a hole in
a cardboard box that's just big enough for the normal cat to squeeze
through.  Put the normal cat's food inside the box.

The best alternative would be switch your cats over to canned food and feed
them seperately on a twice-a-day schedule.  Your overweight cat will
probably lose more weight on a canned maintanence diet than on a dry,
weight-loss diet.  Btw, over-the-counter "light" or 'lite' diets aren't
really weight-loss diets.

Whatever plan works, just make absolutely sure your overweight cat doesn't
lose more than 1% of his body weight in a week.  Rapid weight loss in
overweight or obese cats can result in a very serious liver disease called
hepatic lipidosis (fatty liver syndrome).

Weigh loss in cats takes time, patience and consistency - so, don't lose
faith.  A good pediatric scale will detect weight loss that you can't see by
eye and will help you keep the faith.

Best of luck.

Phil

I have a similar situation developing, though not quite the same. We
have been free feeding for at least 30 years with no problems. But I
just adopted a cat a month ago that was turned into the shelter
because the owners were letting him outside and not feeding him.

Strangely, he is a social eater - won't eat on the counter without
company, so in a sense, he is not free feeding even though the food is
available 24/7.

So, when I am not home, he doesn't eat much, if anything. But when I
am home, he is chowing or begging. I fill the bowl, and he cleans it
out, then starts attacking the bag. He has totally slashed up the
current bag.

So, I had two samples of Royal Canin's "slim" food. I was planning to
give them to my friend who has a very fat cat. I put the one sample in
his bowl, and he liked it. So, I figure I will switch his kibble to
the slim food and see if it works as a mainenance for him. He is not
currently overweight. He just seems to be eating more than he should,
and I would rather he eat more of a lite food than less of a fatty
food. I would rather prevent him from getting fat than wait til he is.

So, that seemed like a great idea til my elderly cat came by and
started chowing on the diet food. Damn. The last thing I need Maynard
to eat is a lite food. He is underweight again, and I am trying to put
some weight on him. He recently discovered the place I am feeding
Jay Jay, and both of them agree that this is the best location to eat.

So, I am going to buy some bowls with lids. One with chubby food and
one with lite food, and I will open the bowl that is appropriate to
the cat. They can eat in the same location, and not eat each other's
food.