One cat is getting fat, one is getting skinny, and they both eat from whichever bowl they reach first

Two cats, same house, same food, completely opposite problems. Smudge is 4 and has gone from solid to properly round, you can't feel her ribs any more and the vet nurse did the polite face at her last weigh-in. Her brother Pip is the same age and has always been lean but is now looking bony along the spine.

The cause is not a mystery. Smudge is a hoover. She eats her portion in about forty seconds and then stands over his bowl until he wanders off, and he is far too polite about it. I've tried feeding them in separate rooms but she has learned that the closed door means Pip has food, and she sits outside it howling, and honestly I usually cave because it's easier.

Also I free feed dry biscuits in a bowl in the kitchen all day, which I now suspect is the actual answer to my problem and the thing I don't want to hear.

How do people with a greedy one and a slow one manage this without the whole day becoming about feeding cats?

Yes, the free-fed biscuit bowl is the answer and no, you didn't want to hear it. Take it up. That is the single change that did the most here.

Then feed timed meals in separate rooms, and accept a fortnight of howling at the door. She's not starving, she's negotiating, and she'll stop when it stops working. Mine howled for about nine days.

A different angle: height. Otis is the greedy one and Millie is the slow one, and the thing that fixed us was putting Millie's bowl on top of a chest of drawers she can reach in one jump and Otis genuinely cannot manage any more, because he's, well, Otis. He can't follow her up there so she eats at her own pace and nobody has to shut a door.

It only works if one cat is meaningfully more agile than the other, which for us is the whole problem stated as a solution.

We went to a microchip feeder for exactly this. It's not cheap and it took our slow one about three weeks to trust the lid, but it means I'm not standing in a doorway refereeing twice a day. The greedy one still sits and stares at it like a safe she can't crack.

Worth saying it doesn't solve the dry food grazing problem on its own, we still had to stop leaving a bowl out.

This exact combination, one cat gaining and one losing in the same household, is one of the more common things people post here, and it's worth splitting it into two questions because they don't have the same answer.

The management half is what everyone above has covered, and I'd back all three approaches: no permanent bowl of biscuits, measured meals rather than eyeballed ones, and physical separation of some sort, whether that's a door, a height difference, or a microchip feeder. What I'd add from doing this badly for years is to weigh the food rather than scoop it, because the difference between a level scoop and a generous one adds up quickly at two meals a day, and to weigh the cats monthly on kitchen scales so you're working from numbers rather than impressions. The site's guides to how much to feed a cat and cat obesity and weight loss cover portioning and the safe rate for weight to come off, which is slower than most people expect.

The other half is the bit I'd not want to see lost in the logistics. A cat becoming visibly bonier is not automatically explained by his sister stealing his food, even when she obviously is. Weight loss in a cat that's still eating has a list of causes behind it, and the only way to rule them out is bloods. I'm an owner rather than a vet, so I won't guess at Pip, but I'd mention his weight at his next appointment rather than treating the feeding arrangement as the whole story.

That last paragraph landed. I'd talked myself so thoroughly into "she steals his food" that I hadn't considered anything else, and he's the one I've been vaguely uneasy about for months. Ringing tomorrow.

Biscuit bowl is up. Day one, and Smudge has already sat where it used to be and shouted at the empty floor.

Update, and it's a mixed one. Pip's bloods came back with something the vet wants to recheck, so we're back in three weeks and I'm trying not to google in the meantime. Nothing dramatic, but it wasn't nothing either, and it certainly wasn't his sister.

On the feeding: separate rooms, weighed portions, no free biscuits. Smudge howled for eleven days exactly as predicted and has now given up entirely. Pip is eating a full portion for the first time in I don't know how long, which would feel like a win if I weren't now waiting on a recheck.