I heard that food symbolizes sex in film and literature. Maybe that has something to do with it.

The girl's gotta eat!

It's a subtle way to show how hungry she is for getting bin laden, and strengthening herself in the process.

Most likley she is just hungry. Sometimes when people are hungry they eat

I think it also shows that she stopped going out because she'd become a target. She was always on CIA property because she was so caught up in her work but also because it was dangerous for her outside. She, herself, had become a but if a detainee to her work.

^^^ This.
Very good. But brick not hit back!

Nailed it.

I think they probably show Maya eating to demonstrate how committed she is; she doesn't even give herself time to take a proper sit-down meal and often eats at her desk. It also removes some of the mystique of what she's doing, makes her seem a bit more human. They're showing that behind these highly classified intelligence operations are real, hard-working people.