Pride Day is a great opportunity to educate people about this, but more importantly it's a chance to stand with our LGBT friends against prejudice, and to demand fundamental human rights for all of us.
Most people believe that both being fat and being gay is a matter of personal choice.
This is true in a sense - what we all choose is to have a fully human life. You'll be expected to suppress a fundamental part of your personality, all the time. Never mind that your soul dies. All you have to do is recognize that you are subhuman and not entitled to a sex life that fully involves you at all levels. If you're really heavy, you'll be expected to undergo dangerous and ineffective surgery to make sure you eat even less.