My Litter-Robots keep track of Jake and Jenny's weights. Every time they use one of them, their weight is recorded. Originally, when I bought the Version 4 robots, I was promised that you could personalize the app with your cats' names so that it could keep track of how often they go to the bathroom and monitor their weights. That feature still isn't here... you have to manually look at the history and keep track yourself... but it's pretty easy to spot which cat is which because Jake has five pounds on Jenny, his more petite sister.
Jake is a big boi.
Not just overweight... he's big. Like he's got some Maine Coon in his genetic makeup. Jenny is smaller by a third, but she's also not as tiny as average cats I see. And both of them have large primordial pouches (abdominal flaps) and excess loose skin on their bellies which make them hang a little lower to the ground than other cats.
When it comes to their weight, I've never been overly-concerned because it's well-distributed. When viewed from the top they are not protruding on their sides. They are slim like regular cats. And you can feel their ribs. Neither is obese. But Jake is heavy, and his vet said he could stand to lose some weight, as it might help with the urinary problems he had back in the day.
When I changed to the new vacuum-sealed feaders, they measure in 1/12th cups instead of 1/10th cups of the old feeders. Since I spread their feedings out to avoid Jake doing a scarf-and-barf, I simply eliminated one of their feedings to see what would happen. Instead of getting .45 cups a day, they now get .42 cups. Not a huge amount, but it's making a difference. Mostly because the cats complain... but partly in their weight.
In the month since the change, Jake has lost 1.9 pounds. Jenny has lost .3 pounds. Probably because Jenny is so close to her target weight and Jake is... not.
But my cats are weirder than most in a number of areas, including how they eat, so this kind of progress with Jake could not be guaranteed. Jake will sometimes skip a feeding or two. Then sometimes he will eat all his feedings and skim off his sister as well. Sometimes Jenny will eat both her portion and Jake's if he doesn't show up. Sometimes she will eat only hers. It's a total crap-shoot. All I know is that if I put down a giant bowl of food, Jake would gorge himself several times. I can imagine him easily eating twice his usual amount of food because he doesn't have any self-control. He'll eat his entire dinner... then come watch me eat mine, hoping for a treat.
I think so long as he's not losing weight too quickly... and he stops losing weight once he's closer to his target weight... this will be a good thing. More healthy for him. But most importantly? He doesn't seem to notice now that he's adjusted to the feeding schedule that's minus a meal.
That's healthy for me... because my cats won't murder me in my sleep.