Like clockwork it seems, the two days right before I start my period I become obsessed with eating dark chocolate. In particular I eat a whole Hail Merry chocolate tart each day, plus most of a 72% chocolate bar over both days.
I'm not a big chocolate person and the Hail Merry tarts especially I would never be able to eat like that at any other time because they are so big and rich. Also it's way more sugar (40-50 grams from maple and cane sugar over two days) than I usually tolerate from a strictly taste point of view (I don't have a sweet tooth).
I know many women experience the same thing! But why? Is is conditioning/habit? Such as craving popcorn when you go to the movie theatre? Or is there something in chocolate that your body wants more of at that time? And can you get those things from another food that will satisfy the chocolate craving? It's a lot of fat and sugar and extra calories (like 600 each day!), but I don't crave other caloric fatty or sweet things, just the chocolate.
Dark chocolate and almonds are relatively high in Magnesium.
You may want to take a magnesium supplement before bed (e.g.: 200-600 mg Magnesium Glycinate.) I've been doing this for some time and it does help reduce my chocolate cravings.
Seems that both magnesium & zinc levels fluctuate during our cycles, which may play a role: http://www.ncbi.nlm.nih.gov/pubmed/3674170
My guess is that it has to be hormonal related, since it happens according to a woman's cycle. The strange thing for me is that since on the paleo diet, my cravings have been spreading more. Last 2 times it lasted 1 week prior menstruation (yes, you're lucky to have only 2 days!), and now this time it seems it started earlier, on the 3rd week of my cycle, but milder. A quick google search seems to mention serotonin as the culprit, and if so, looking for comfort food would make sense.
I too am not a big fan of chocolate (or anything bitter, actually), and it surprises me every time I crave for it. But I also crave sugar in general when on PMS, so I suspect that it isn't just magnesium that I look for.
I've found this funny: