I was told that your brain sends a signal that you dehydrated but it comes out that you are hungry, so you have a glass of water and wait 15-20 minutes and if you were only dehydrated it will settle. But if you are still hungry then you have a lite snack. I have found that if I buy a "Optifast" snack bar and cut it up into squares and place it into a container in my bag, when I do have the cravings I can just have a square or two and that seems to be enough.
The comment by Tarz about the chocolate at work I totally understand, we have been fundraiser with the "freddo frogs" for the last 2 YEARS, right there in front of me at my desk. And as soon as I had a bad customer/phone call I would grab a frog and devour it without really wanting it, but thinking that it will MAKE ME FEEL BETTER, never did and just help whack the weight on. So sometimes you can't avoid the temptation but have to stop and think WHY you think you need it. Once I start thinking why I needed it, 9/10 times the want started to fade and something else came up and I was side tracked and forgot about the chocolate.