Can't answer your thryoid question but you could try out what staci said. I find it a bit harsh to cut down from the 1.25 cup of food Kai gets so I sometimes only give him 3/4 cup of kibble and some greenbeans to make him feel more satisfied. As long as he isn't always hungry, I wouldn't find it cruel. And (like someone said) you can try feeding the same amount (or less) but in 3 smaller meals. It'll make her metabolism go up and should help her lose a few pounds too. I try to feed them 3 small meals instead of 2 when I can.