I'm going to turn down a girl because she's overweight
That's too bad. Why do you want to turn her down?
She doesn't have any goals in life, she just wants to eat and get fat.
I understand not being attracted to all body types. It's good to keep in mind, though, that many obese people have certain genes that make it harder for them to lose weight.
I don't care, I'm turning her down.
If you aren't attracted to her, that is fine. As long as you are respectful, you can do what you want.