Why do fat people eat fast food and then complain they e fat?
I would suggest that it is far more complicated than stupid, lazy, ignorant. I believe that obesity is related to mental health and that many obese people have emotional/mental problems. We readily accept anorexia nervosa as a mental disorder and so it would be unacceptable to act in a derogatory manner towards a person suffering from this disorder. Likewise, I think that it is not acceptable to say such derogatory things about an obese person as you are likely to make their mental or emotional disorder worse. I know it is really fun to be mean to other people so that you can feel better about yourself, but overweight people have feelings too and you might want to consider the damage you are doing by being so cruel.