I can't stop laughing even though I shouldn't, has this ever happened to you?
Maybe. But are you truly serious? What is causing you to be unable to stop laughing?
There have been many life changing things happened in my life, I've gained a lot of weight.
If you find that you are laughing in unexpected situations then the polite thing may be to excuse yourself. Dont beat yourself up about it because there are many people who find themselves laughing when situations become uncomfortable.
Lol
Being able to laugh about yourself is somewhat healthy. But over eating is not. Try to either take the laughs somewhere there are not many people around so they won't think you're insane, or loose the weight.