How do I lose weight fast without exercise?

It’s not because I’m lazy and refuse to move my ass. I had a injured knee last week and the doctor said I cannot do any exercise for at least 1 month. I need to lose weight fast because next month is my sister’s wedding. I’m 17, 167cm, and 160lbs. With my current size, I can’t even fit into a dress :*(
Please help me to at least fit into a cute decent dress?
Thanks in advance!