How many calories are in beer?

According to the United States Department of Agriculture, one can of regular alcoholic beer contains 153 calories. Calories in beer are largely derived from the grain source, such as barley or wheat, used in the fermentation process.

Beer is comprised of mostly water, but it relies on a starch or grain source to create sugars that are then fermented. Yeast is an essential component in the fermentation process, as it consumes the sugar to produce alcohol and carbon dioxide. Another component found in many beers is hops, which adds flavor and bitterness to beer and can act as a preservative.