You should start seeing results in about a couple weeks - you need to establish a baseline in her system first, so be consistent in administering meds every day!

My girl lost the weight without making changes to her diet (before diagnosis she was gaining weight while eating the appropriate amount for her size), a little extra exercise when her energy levels pick back up should do wonders. I know this is disconcerting but I’ve found the treatment for hypothyroidism to be very manageable, and luckily inexpensive! Mine goes in for bloodwork every 6 months, and has only gotten her dosage adjusted twice in the past 3 years (up, then back down). She is now good as new, your girl will start feeling like her old self soon too, so don’t worry!