Where Beer Calories Come From

In the previous post, we discussed how beer was produced. Such a background was necessary to establish the chemistry necessary to understand calories. The main ingredient we're concerned with is the malted barley. For calorie purposes, water and hops, a type of flower, don't have an impact.

Malted barley is what's considered a cereal grain and has a large amount of carbohydrate, small amount of protein (gluten) and a trace amount of fat. In the process of brewing, yeast will convert most of the carbohydrate to alcohol. So, beer has calories from three sources:

• Alcohol - 6.93 calories per gram
• Carbohydrate - 4 calories per gram
• Protein - 4 calories per gram

Alcohol is typically measured in alcohol by volume, though alcohol by weight may be used. Either way, its not a big deal, because ABV times .789 equals ABW. The real key to how caloric the beer is has to do with the concentration of sugars in the wort, also known as original gravity. So, a wort with a high amount of sugar will lead to a more caloric beer. It's pretty simple. To get a proper estimate of how much fermentation occurred, the original gravity should be compared with the final gravity. It should also be noted that the amount of fermentation (conversion of sugar to alcohol), isn't too big of a deal in determining overall calories, even though alcohol is more calorically dense than carbohydrates. Lastly, the protein isn't affected by fermentation, and it is not of the muscle building variety, due to low bioavailability.

In noting the sugar density of the wort is what determines calories, the following is a list of beers by type with approximate calories per 12 ounces.

• India Pale Ale: 200 - 350 calories
• Porter: 190 - 240 calories
• Pale Ale: 170 - 250 calories
• Brown Ale: 170 - 220 calories
• Wheat Beer: 140 - 190 calories
• Lager: 125 - 160 calories
• Pilsner: 95 - 150 calories
• Light Beer (lager or pilsner): 55 - 120 calories

The above list is useful if you have no idea what you're drinking, just the style. The amount of alcohol  is somewhat proportional to the calories, so the beers higher on the list tend to be stronger. Check out The Efficient Drinker for a more exhaustive list of beer brands and their calories as well as alcohol by volume.