“When you drink alcohol, its broken down into acetaldehyde (basically vinegar) , which the body will burn before any other calorie you’ve consumed or stored including fat or even sugar. So if you drink and consume more calories than you need , you’re more likely to store the fat from the Cheez Whiz you ate and the sugar from the Coke you drank because your body is getting all its energy from the acetaldehyde in the beer you sucked down.
Further, studies show that alcohol temporarily inhibits “lipid oxidisation” – in other words, when alcohol is in your system, it’s harder for your body to burn fat that’s already there. Since eating fat is the most metabolically efficient way to put fat on your body – you actually use a small amount of calories when you turn excess carbs and protein into body fat, but excess fat slips right into your saddlebags, no costume change necessary – hypothetically speaking, following a high fat – high alcohol diet would be the easiest way to put on weight”
Rachael Coombe, Elle.com