If you have Internet access when you are at work then you could use 1 of the many online calenders to track what your eating.

If you set up Breakfast 8am, Snack 10am,Lunch 12pm,Snack 2pm, Evening 6pm Meal and copy this to everyday. Then it will show up on each day at what times you have set. You can enter what food you have had so you can later work out your calories.

Hope it makes sense if set up ok it should work fine.