It might be acceptable but is it effective? Thyroid disorders are not common, but food addiction is extremely common. The same way you couldn’t understand what drug or alcohol dependency feels like if you’ve never felt like that before, you couldn’t understand what food addiction is like if you don’t have that experience with food.
It’s clear that there is a spectrum of how people respond to food, from “always hungry and literally never not wanting to eat” to “forgets to eat for days and barely notices until they pass out”. I personally know people on both ends of that spectrum and every place in between.
So I think your response is a little insensitive, or at least lacks empathy. To boil it down to the classic “stop stuffing your face” or “basic math” assumes your level of willpower required to not overeat is applicable to all people and it can’t possibly be different or harder than it is for you, so the only explanation is that everyone else must have less willpower than you.
Either that, or they feel like they are starving all the time and are literally addicted to food. Most science shows that it’s that one, but feel free to believe whatever you wish.