I find it hard to feel any sympathy for fat women
That sounds harsh. Why don't you feel sympathy for overweight women?
Fat is unhealthy and I don't want to be unhealthy.
It is not healthy to be overweight but you don't know their reasons for their weight problems so shouldn't judge them for it. People will think that you are judgmental if they find out.
It's my right to judge them, they need to stop being so fat.
Your judgment of them doesn't help them to lose weight, it's only gratifying to yourself. Instead of judging other people, focus on improving yourself and being more accepting of others.