Kelly, I can relate to this question very well, but fortunately for me, most of us at our office take lunch at our desks, so there isn't as much pressure.
What I do, is arrive early for work, and do my prayer and study before my day gets started so that I can really concentrate without being interrupted. Also, since I take lunch at my desk, I use a program called e-Sword so that I may read and study further. I know in many companies, you aren't allowed to install software on company PCs, but here in my office, this isn't an issue. Also, just because you are on a fast, doesn't mean that while you are at work, you have to be neglecting your job. In my opinion one of the things that fasting is for is about being in deep communion with God. You can interpret that as you will, but when I can't be studying His word because of work, it doesn't mean that I can't still be communicating with Him or concentrating on Him. Sometimes I find myself asking Him what he thinks about certain situations that arise during the day or phone calls that I get. God knows your heart and I don't think He is going to condemn you for holding down that job. After all He tells us that we are to work and support our families as well as work to server Him and His kingdom.
As for people noticing you are different, it may be different at your office, but most people here are too busy with their own lives that they hardly take notice of me being any different. You can still go out to the machines with them and talk or do anything you normally would do. I find that one of the rewards of a food fast is that God is giving you mental and physical strength, so much so that you can still enjoy spending time with other people who are eating and yet not have to take part in that and break your fast.
Also as stated a hundred times in this forum, fasting can be from anything that you spend a lot of time doing. It doesn't always have to be with food.
I hope that I haven't rambled too much and that my comments may help you in your fast.
May God Richly Bless You...
Bill