While it is not ideal to lunch at your desk, we don't all have the luxury to avoid it. So let's make the most of it:
1) Bring your lunch (you can control your healthfulness and minimize expenses)
2) Eat food that will give you energy throughout your day (nuts, vegetables, grilled chicken and fish, vegetables, tea)
3) Cook/prepare for the person you want to be, not the person you are... you dress for success now how about your meals?
Set the standard for your food office culture, and see what changes take.