According to About.com, one 25-gram shot of Scotch whisky has 56 calories. All of the calories come from alcohol. Scotch whisky contains no protein, fat or carbohydrates.
The Scotch Whisky Association explains that there are five types of the alcoholic drink. Single malt comes from only one distillery and does not contain any cereals other than malted barley. Single grain is also made at a single distillery, but it sometimes has other grains added. Blended whisky is a combination of at least one single malt with one single grain whisky. Blended malt brings together single malt whiskys from different distilleries. Blended grain mingles single grains from separate distilleries.