She is a rescue as well, who has always had food issues, presumably from being food deprived as a stray.
I originally began feeding Fancy Feast Classic Pate because it is supposed to be a good "diet" food at only 99 cal per can. She is now up to 16 lbs from eating that. 😓
I've recently switched her to Evanger's organic chicken at the rec of another DUer. (TY!) as it's real chicken vs Fancy Feast's byproduct & meal protein. Ick!
Grains & carragenan can affect cat digestion, I've found from researching her weight problem.
Also, cats must lose weight very slowly for health reasons, so please be careful.
Weight gain can also be causal to idiopathic urinary tract infections, which she has had in the past.
My girl will not play with anything, so I've bought her a very tall kitty tree to increase her activity level. She loves her tree! Took to it immediately & at least is getting a bit more exercise.
I can't say she has lost any weight yet, but within 2 days of beginning to feed the Evanger's (about 1 month ago), her coat is once again very shiney! A good indication that I'm on the right track here.
Every 3 hours, she demands food. If shd doesn't get fed, she gets very frantic - banging cabinet doors, trying go knock my phone ouf of my hands, etc., then she throws up.
I also feed her tiny amounts of Blue Indoor dry formula when she demands food.
I also bought Doc & Phoebe's feeding system. These are 3 plastic mice-shaped plastic food holders, covered with fabric that she is supposed to hunt for. No luck yet, but I haven't been digent in transitioning her dry food to this system (again, in hopes of increasing activity level).
Here are links to these products, if they are of interest:
Tall heavy duty cat tree (on sale now for $114. I paid $132 a couple of months ago - 5 star reviews)
https://www.chewy.com/frisco-76-in-xxl-heavy-duty-cat-tree/dp/240966
Doc & Phoebe's Indoor Cat Feeding System (4 star reviews)
https://www.chewy.com/doc-phoebes-cat-co-indoor-hunting-cat/dp/179102
Evanger's organic chicken (4 star reviews - a bit more expensive, but these are much larger cans than Fancy Feast & still 24 cans - $49.39 with 5% autoship discount.)
https://www.chewy.com/evangers-organics-braised-chicken/dp/44998
I hope this helps. It's an ongoing struggle here with her weight. I've bought every type of cat toy known to humans. She will not play.
I also bought her Japanese Silvervine to try to get her to play as she is not affected by catnip, but have yet to try it.
Please let us know how your babies are doing.
I hope this info is helpful.