Alcohol has 7 calories per gram. Unlike carbs, protein or fat, alcohol's calories CANNOT under any circumstances be stored as energy (ie fat, muscle or glycogen). Therefore your body must burn alcohol before it can burn any other cals floating around in your system. This effectively means that non alcohol calories will likely be stored as fat/glycogen if consumed at the same time as the alcohol. This is true even in ketosis. However, if you drink alcohol without any other calories, it can't make you fat unless your total daily calorie intake is above maintenance. A significant proportion of alcohol calories gets burned off as heat. Vasodilation and an increased feeling of warmth are noticeable after consumption. Because of this it appears that alcohol, without directly increasing metabolism, can result in an increase in calories bured as heat rather than stored as fat. Modest alcohol consumption also increases insulin sensitivity in women, but not men (this is assuming you're not on a keto diet), so if used in the right quantities at the right time, it may aid women in gaining muscle. A single drink as part of a post-workout meal is ideal for women, especially if they're premenstrual. Otherwise it makes good sense to avoid alcohol if you're on a calorie restricted diet since it's basically empty calories and hard on the liver.