There is some sort of agreement that the calories and other nutrition data, except of the percent of alcohol, do not need to be shown on the labels of alcoholic beverages.
But these nutrition facts are listed in the USDA.gov nutrients database (search for beer, wine, vodka, gin...)
For example, 1 jigger or 1.5 oz of 80 proof vodka has 97 Calories. These calories represent "metabolic energy," which is energy that can be actually used by your body.
A source that claims that alcohol containsprovides metabolic energy:
- European Journal of Clinical Nutrition: Alcohol has 29.6 kJ (7 Cal) of combustible energy and 29 kJ (6.9 Cal) of metabolic energy per gram.