I'm a bit confused. Your BMR doesn't even put you in the 'overweight' category...so I highly doubt people will be laughing at you waddling along :/ I think you're probably exaggerating how fat you are. If you want to lose weight, by all means do, but there are some absolutely massive people out there...people won't blink an eyelid if they see you exercising.
How about joining a running group if you can't afford the gym?
What will other unis think?