Your thyroid gland is in your neck, very close to your head, so she's basically right. If you're such a fancy "healthcare professional," why can't you fix your weight problem on your own? Maybe you quacks deserve each other.

I use to work in a hospital and doctors are just regular people often looking for the quickest/simplest answer so they can clock out, just like anyone else. Though thyroid disfunction is found in 33% of obese people so you'd think she could just run a test to rule it out. Assuming you have insurance...

you should have asked to see her medical degree

Calories in < Calories out = you loose weight. You shold know that (if you are healthcare proffesional), eating less will always lead to less weight. Anything else is just excuses.