Before I go on I must admit that I have not read all of the posts in this thread so If I what I am about to write has already been written I apologize but this is a topic that I have strong opinions about.
First let me start by saying one of my greatest beliefs is that the only person you can truly affect change with is yourself. This and a strong belief that everyone, no matter their religion, colour, sexual preference, size and anything else that makes us different deserves to be treated equally with the same respect that I would expect to be treated myself.
If you choose (and I believe that this is a choice) to feel negatively about an individual that you do not know based on appearances than it is you that has a problem not them. One of the reasons people judge other people who they do not know is a caused by fear and shame of their own shortcomings.
Before you can forgive people for their differences you must forgive yourself, this may seem easy but it is often not. The best place to start is to remember that, as stated earlier, the only person you can truly affect change with is yourself.
So go ahead and forgive yourself for being flawed and remind yourself that you are doing this because you want to be healthier not because being fat makes you a bad person. Once you forgive yourself you will then be able to forgive us.