"I am following what my doctor has advised me to do. Because I KNOW I am a sugar addict. As the day nears an end at work I am thinking about where I am gonna stop and what I am gonna buy."
From my own experience, i would say that this feeling is because your blood sugar levels are low and you need to eat something. You should have something to eat to take the edge of this hungry feeling so you can get home and eat properly, without suffering or risking caving in.
When i go to the city, i sometimes take a bag with a few pieces of fruit, a vegemite sandwich on wholegrain. Or a banana sandwich is also good.
The latter is good if you are really hungry and/or you know its a while before you can eat properly and the fruit is good if you are just a little bit hungry or bored. You can leave the butter off the banana sandwich if you want to keep the calories right down.