This link is very short and succinct but it manages to explain what I remember being taught except for the fact that it doesn't go into the lower classes very well, http://www.bartleby.com/67/1000.html,
I hope you find it helpful.
Sorry, just checked and realised that it doesn't take you straight there, type in French Revolution at the top and look it up under World History Encyclopedia, click on the first search it throws up.
I don't think the problem was a shortage of bread, the problem was the price, it was beyond the means of many ordinary French people and ironically despite a revolution, it wasn't until after Napoleon was ousted that some finally did something about it.