What to Eat and What to Wear????

I will be working twelve hour shifts and not able to leave our building for lunch or anything so, what should I take for lunch and snacks?   My first week I found I eat all the time, I was hungry all day.  My first twelve hour day I got to go to lunch with our CEO so I only had to pack snacks and maybe something to eat before I went home.  I have been trying to put together a list of easy to carry items to snack on but still semi healthy.  I can ill afford to gain weight at this job.  I am also having some difficulty in what I should wear and what will be comfortable.  Personally, I think pajamas would be a great idea but my manager frowned on that idea.  We are supposed to dress business casual so, I am trying to be professional but still comfortable.  So far, I have worn dress pants and a nice top and skirts and tops.  We do get to wear blue jeans on Fridays or something more casual.   I only own a couple pair of blue jeans so that will limit my casual days.  I saw something on Facebook yesterday; a girl said when she was out and about she was either really well put together or she looked like she was homeless.  That is me to a tee.  There is no in between and I kind of feel that way about casual Friday.   I am either going to look professional or I am going to look like I just got out of bed.
If you have any advice please, please comment below.   Also if you have any ideas about what to pack for lunches and snacks I would love that too.  I will be sharing more on both of these as I go through this schedule adjustment.
This is all new territory for me so stay tuned. . .