Hi there,my Rocky,13 yr old tabby also has HT,went from 16lb's to 12lb's before he was diagnosed .
He too has lost muscle-mass in his hindlegs,but has gain 1 lb.
I always thought cats with HT have a very good appetite,Rocky certainly does.
He takes 2,5 Tapazole daily,1 morn,1/2 mid-day and another whole at night.
I wish my cats would eat raw,they will only take a little raw chicken or beef,not a whole meal.
They all eat Wellness canned,Rocky however has had loose stools for about 1 yr,I add Slippery Elm Bark to his food,to try to combat that.
"The cruelest animal is the Human animal"
3 kitties,Rocky(r.i.p my boy),Chico,Vinnie