The liver cells are the only cells in the body that can make adequate amounts of the enzyme, alcohol dehydrogenase. This is what effectively breaks down alcohol. When alcohol is present the liver cells are forced to metabolize alcohol (not fat) and the fatty acids accumulate. In other words the liver is too busy detoxifying the alcohol that has been consumed that it doesn't burn fat effectively.
Alcohol actually counts as 2 servings of fat per 4-5 ounces of wine, 1 light beer or 1 ounce of hard liquor according to the diabetic exchange system.
Alcohol is a harsh diuretic, but by being a diuretic, alcohol depletes the water soluble B vitamins. The B vitamins have numerous functions in the body (fighting stress and helping us digest food properly) but in terms of weight management they are important in supporting the fat burning process.
Rather than getting stored as fat, the main fate of alcohol is conversion into a substance called acetate. In fact, blood levels of acetate after drinking vodka were 2.5 times higher than normal. And it appears this sharp rise in acetate puts the brakes on fat loss.
A car engine typically uses only one source of fuel. Your body, on the other hand, draws from a number of different energy sources, such as carbohydrate, fat, and protein. To a certain extent, the source of fuel your body uses is dictated by its availability. In other words, your body tends to use whatever you feed it. Consequently, when acetate levels rise, your body simply burns more acetate, and less fat. In essence, acetate pushes fat to the back of the queue.