Being made fun of and being oppressed are two separate things. You have endured ridicule, and that's unacceptable. However, you don't live in fear for your life and livelihood. You don't have a long history of people like you being unable to find work, unable to choose where you live even if you can afford it, unable to walk alone at night, unable to have a romantic relationship without experiencing death threats, unable to own a profitable business. Oppression is not something that makes you unhappy. It's something that pushes down on you at all times, and keeps you in that place because there's nothing you can do to change who you are.
Weight is something that the individual has the ability to change, if even a little. Unless you have a medical condition that keeps you obese (which isn't common), you have some control, and even if you do, science is amazing and you can be treated. There are, of course, other factors that chip away at that control (financial ability, space in one's schedule, depression, etc.), and there is no denying that it seems impossible to get past them. However, you're not alone, and with help, you can.
You can't change the color of your skin. You can't change your sexual orientation. Those are 100% fixed. No amount of work will make you less black/gay. You just are.
