I personally have gotten way more flack from being thin that I ever did being fat. 
When I was fat they were too skeered to say anything.
As I pointed out above, observation (and/or ‘conclusion’) bias has been studied extensively. It is a very real phenomenon. If your question above is real (as opposed to rhetorical), I would respectfully re-invite you to look at the link I provided previously, which introduces the findings of this area of inquiry.