Bitsy, left, and Thurston rule the roost at the home of columnist Amy Calder. Want a friendly feline feeding tip? Don’t have one underweight cat that you’re trying to beef up and another cat that’s overweight and in need of a crash diet. Amy Calder/Morning Sentinel

Bitsy is getting to be an old girl, at 16.

She’s black and gray and looks like a little Maine Coon.

As she ages, she loses weight. A year ago she was nine pounds and now she is seven. The vet told us to try to give her dry kitten food, which has more calories, and kitten treats.

It seems to help keep her weight stable, at least for now.

But trying to feed her these treats when her housemate, Thurston, is a 23-pound behemoth of a cat who is supposed to lose weight rather than gain, is a challenge.

Our vet addresses him as Chubby when we visit.

“No more climbing trees, Chubby,” he says, referring to the time a neighbor’s German shepherd got loose and chased Thurston up a tree. He had stayed there for hours before clawing his way down and apparently jumping the last several feet — and injuring a hind leg.

That was a couple of years ago and he’s all better now. But Thurston, who is orange and white, is what you might call our special cat, always getting into some kind of scrape or needing some extra attention. The vet says he needs to lose some pounds.

But how do you manage meal time when one cat needs to gain weight and the other to lose it?

Thurston needs to exercise more but it’s winter and when he and Bitsy cry to go out the back door in the morning, they don’t stay out for long.

We have always let them eat when they want. We fill their bowls with dry Iams cat food and water and that’s it.

I didn’t want to change that routine for fear it might rattle them, so in an effort to try to fatten Bitsy up, I have been giving her a little spoonful of wet food once a day and the little dry treats, twice. And I also try to coax her to eat the kitten food brand of dry Iams.

But this new method of operation is tricky. Thurston has learned to recognize the sound of a spoon being taken out of the drawer to scoop wet food out of a can. He can be dead asleep in the bedroom closet — his favorite hideaway — and appears like magic as I feed Bitsy the good stuff.

If I open the plastic package of cat treats, he surfaces just as quickly. Same with the dry kitten food bowl. He has ears and eyes like a hawk when it comes to cat consumables.

Lately I’ve carried Bitsy and her special food into another room and closed the door until she is done eating. What does Thurston do? He rushes to the door and lies down in front of it, waiting for her to be released.

He’s such a curious cat when it comes to human food.

He loves a taste of yogurt but couldn’t care less when I take a potato chip out of a bag, though Bitsy rushes to my side to snag a tiny piece. He just gazes at Bitsy, who also appears suddenly if she hears a blue corn chip being consumed. However, when she smells it, she retreats, knowing it is not a potato chip. Thurston has no interest.

But back to closing her in a room to eat, sans Thurston. I’m afraid I’m giving him a complex.

“Why is Mummy giving Bitsy the good stuff and shooing me away?” he must think.

We bought him some cat toys we hoped would get him moving and thus losing some weight. They’re basically a stick with a string attached with a small toy on the end.

Thurston does flail around a bit when we deploy it, but mostly he just wants to chew the string off. We have to keep tying the toy back on.

I know when spring comes and the snow melts, he’ll be out running around in his little backyard jungle so I’m not too worried. Hopefully, he’ll drop some pounds.

Meanwhile, we’ll just keep plying Bitsy with treats, hoping she’ll gain a few.

The upside? They keep us humans running. We don’t need a gym.

Amy Calder has been a Morning Sentinel reporter 34 years. Her columns appear here weekly. She is the author of the book “Comfort is an Old Barn,” a collection of her curated columns published this year by Islandport Press. She may be reached at acalder@centralmaine.com. For previous Reporting Aside columns, go to centralmaine.com.