Bigotry, unfortunately, can come in all sizes, shapes, color, ages, and ethnic groups.
Better to surround yourself with a rainbow of people who can bring positive energy into to your life and avoid those who hate others just because they are fat, skinny, black, white, etc.
Fat discrimination seems to be the last bastion of institutionalized prejudice; some day, it will change, but for now, just be the best possible person that you can be and try to educate those who would judge you unfairly, for example,
"All fat people are lazy. You are fat; therefore, you are lazy."If you can't educate such numpties, then it's best to avoid them.
Also, don't resort to reverse bigotry to judge thin people unfairly. For one thing, you don't know how hard that person may work to maintain his/her shape.
Even so, most thin people are well-meaning, even if the don't always get how difficult it can be to lose and maintain weight loss.