Consider a list of traits associated with fatness – lazy, stupid, undisciplined, unattractive, unsuccessful – against a list of traits associated with thinness – active, smart, disciplined, attractive, successful.
Now replace the words fat and thin with poor and rich – or with black and white.
People of all body sizes laugh at fatness, including fat people because many believe their fatness to be a temporary state due to a lack of such variables as time, energy, willpower, or even illness. In fact, fat people are just as likely to hold anti-fat attitudes as slim people because they internalise the attitude they’re surrounded with their entire lives.