I work about 50 hours per week. I make it a point to pack my lunch every day in a large carry cooler. I keep healthy snacks and eat small portions throughout the day. I workout around lunch which keeps my metabolism going in the afternon. This keeps me from needing any junk or caffeine boosts later in the day.

You have to make health a priority. Saying you "don't have time" or "work doesn't allow it" is, i'm sorry, just an excuse to not put the effort in. There are alwasy options. I've had many employers and not one of them raised a complaint with regard to me working out for an hour in the middle of the day or when it fit the schedule. This assumes of course there are no emergencies. They've always been ok with this because I get my work done and often come in at 6:00 AM and work past 5:00 PM.

There are a lot of jobs in IT, despite the economy. This means you have a choice to choose your employer if they're pushing you unreasonably or are choosing to remain short staffed in the long run.