I browse quite a range of websites on dieting and healthy eating, and there’s the occasional article targeted towards office workers. Here’s some of some of my favourites out of those I’ve spotted recently:

• Is your job making you fat? - from Weight Loss Resources
  A short article with good quick tips on how to cope with office events like working lunches and people’s birthdays.
• Six ways to improve your diet at work - from Diet-Blog.com
  Another quick article with sensible, easy ideas.
• How to … exercise at work - from the Guardian.
  A rather tongue-in-cheek article: amusing, but don’t take the suggestions too seriously!
• Are colleagues bad for your figure? - from the Daily Telegraph
  A fascinating, in depth discussion of how the eating habits of colleagues (if you’re female) are likely to impact on your own.