what causes it? Hypoglycemia
You can read about it in "Under The Influence"
Alcohol is absorbed quickly into every cell of the body. It even penetrates the brain. The body receives it as quick energy - thus the euphoric, happy personality with the first few drinks. The body processes the alcohol faster than any other nutrients, calories, proteins or sugars.
The alcoholic body becomes addicted to alcohol because it needs it's quick fix. The body begins to scream for a quick fix of super energizing alcohol.
So a sober alcoholic is being screamed at by the body to get another drink and get that quick energy. It takes a new healthier routine and time to overcome the addiction and physical cravings.
I was hypoglycemic a long, long time ago. I would become a bear when I got hungry and my sugar dropped. Look Out! Growwwwwllllllssss! My husband and family knew to give me something to eat quickly. Then I discovered a neat trick - I could have a cocktail while we waited 45 minutes for our tabled at restaurants. mmmmm, no more growling, just pass the vodka please!
I could give my body the quick energizing, sugar boost of alcohol and hold off on eating for hours. I became an alcoholic.