I know someone who is relentlessly judgemental; particularly about overweight people (ironically, she too is overweight). She's exhausting to be around but she also provides a lesson.
Being critical or judging other keeps us from seeing the object of our criticism as a person. It keeps us from looking pass what we view as a flaw, to examine what may be at the root. They are reduced to a label.
The toxicity emitted is high and my encounters with this person are kept brief. However, I shudder to think about what part of me I am blind. It also reminds me that we are made into what we become. Some of it through our own choices but a lot through circumstances. Kindness begins with being kind to ourselves.