Good thing it wasn't Gal Gadot...you might not have been able to type at all...
I had an E.Cat back in the 1970's and 80's for several...maybe 8?...years. I believed it was M.electricus but back then I didn't know there were any other members of the genus. It grew from only a couple inches to about 18 inches in that time, and certainly wasn't hurting for food, so I suspect that they are perhaps slower growing than things like RTC's, etc. but don't know for sure.
I remember vividly two things about that fish: first, how it caused me to reflexively yank my arm back when it "hit" me once, resulting in putting my elbow through a pane of glass and needing some stitches. Still have a very obvious 3-inch scar as a reminder.
And second, I remember that fish on several occasions simply decided to go on a diet for sometimes several weeks at a time. No changes in environment, food, etc...no obvious cause for these little snits. He just stopped eating completely...and then started again just as inexplicably.
I've read several extremely experienced cat keepers, including our own
thebiggerthebetter
, commenting on how some cats do this. I had similar issues with a RTC and even a wild-caught Bullhead over the years; they always came back strong after a few days or weeks as though nothing had happened. In contrast, other biggish cats I have owned...TSN, Jelly Cat, some others...never, never...
never...turned their noses up at proffered food for many years on end, regardless of how much they had already eaten.
My picky ones may have lost a bit of mass when fasting, but never could be described as thin or emaciated. When they started eating again, I was very sparing with their food intake for a few days to prevent problems with regurgitation, etc. but there were never any issues.
Does your cat look merely empty-bellied, or is it starting to look actually emaciated? Beyond suggesting that you look for actual signs of excessive loss of muscle mass, I have no real suggestions. Good luck with your cat, and please keep us posted.