This may belong in GQs, if yes, apologies:
I just recently ended what would be called a moderate (or heavy, depending on your definition) drinking habit (pretty much everyday for about 6 years).
Now I can’t get enough sugar. I never ate it before and now it’s just overwhelming.
Is there a biochemical explanation for this change or is it just psychological (replacing one vice for another, admittedly less pernicious, one?)
Or am I turning into a fly?
Depending on what you drank, it may just be more of the same. A Rum & Coke, for example, has a lot of sugar.
BTW, Congrats on going on the wagon!
Dunno but it sort of happened to me too. IIRC the alcohol breaks down to a form of sugar so maybe your body is trying to get that same sugar elsewhere (sort of like Pica (sp?) only with sugar).
I ate freezer pops like they were going out of style because I also had the need for something bold in my mouth (yeah yeah make your own jokes here). It was cold, crunchy, and sort of sweet. Very few calories though!
I heard this from a friend who was in the early stages of his recovery. His wife would meet him at the door with a candy bar, he said it really helped with the sugar cravings.
Susan Powter (yes, THAT Susan Powter) has a book about this called Sober – and Staying That Way http://www.amazon.com/exec/obidos/tg/detail/-/0684847973/qid=1053033941/sr=1-2/ref=sr_1_2/102-7261044-2900100?v=glance&s=books
which sort of ties into her whole “eat healthier” thing. It’s been a while since I read it but I think the jist of it was along the lines of: alcohol is a simple carbohydrate which the body quickly processes into sugar (thus the cravings when you stop.) She also went on to theorize that the more sugar you’re eating, the more you’re likely to crave alcohol. (At some point I think she accused Alcoholics Anonymous members or going to meetings just for the doughnuts, heh.) She tells some pretty harrowing stories from her drinking days; it’s an interesting read. Your library probably has it if you’re interested.
I’ve read somewhere that there’s a pretty high correlation between hyopglycemia and alcoholism. I’ve also heard it recommended several times at meetings that if one gets the urge to drink, he or she should eat something with sugar in it. There are times when I crave sugar intensely and I go through boxes of Ferrara Pan candies, candy bars, sodas, iced tea. May not be healthly, but it’s a hell of a lot better than drinking.
When I got sober (both times) I developed a ferocious sweet tooth. And, both times, it’s evened out. Still, I gained about 25 to 30 pounds this time around… and the labs I just got back today show I have high cholesterol… Ah well, it could be worse. 
There is actually a Rehab center in Minneapolis that bases much of its treatment on nutrition and the biochemical results of alcoholism. They believe that in many cases Alcoholism and hypoglycemia are VERY closely linked. more info here.
There is a very real biochemical explanation for sugar cravings, especially following a period of alcoholism. As I understand it, alcohol & sugar have very similar effects on brain chemistry by impacting beta-endorphin and serotonin receptors. People who have naturally low beta-endorphin & serotonin levels have a lot of those receptors, so that “hit” causes a high, which the body craves since those receptors aren’t getting enough of the natural chemicals. Like alcohol, the more you eat sugar, the more you need to achieve the “high.” Sugar and alcohol addiction/craving can be controlled with diet for some people (plenty of complex carbs, protein with every meal, reduce simple carbs & sugar).
Here’s some info on how sugar/alcohol affect brain chemistry. You might also check out Potatoes, Not Prozac, which goes into further detail.