All beer contains sugar - it's a necessity in order to create alcohol. However, the overall sugar content varies based on the style of beer in your glass. Below I'll explain how beer is made, why there is sugar in beer and how much sugar you can expect to find in different types of beers, ales and lagers.
How Is Beer Made?
Beer, for the most part, is a healthy beverage made with four natural ingredients. These ingredients are water, hops, grain (mostly barley, but this can vary based on style), and yeast. The brewing process is actually surprisingly simple to understand, yet extremely difficult to master.
Between all the combinations of hops, yeast, and barley alone, there are thousands of ways to combine these ingredients to brew a beer. This is why there are so many styles of this popular drink. But how does this relate to sugar in beer? Let's take a look at the brewing process to find out.
The first step in brewing beer is to mix all the grain with hot water. This is called the "mash". In essence, this step is all about extracting the sugars from the grain. The boiling water breaks down the grain and extracts as much sugar as possible in the process. Depending on how much grain is present and the type of grain used, this amount can vary dramatically.
Now that the brewer's have some hot, sugary water, they add in hops. Hops don't actually add much sugar to the beverage, so we won't discuss them much. However, if you enjoy India Pale Ales (IPA) or like your beers to have a more floral taste to them, you can thank hops!
The next step in the process is to add the final ingredient to the mix. Yeast.
Yeast is a microscopic organism that loves to eat sugar. The byproduct of this consumption is alcohol. As yeast chews up the sugar in wort (this is the term for beer in it's early stages, before yeast is added) it excretes alcohol. Therefore, in order to have an alcoholic beverage like beer, sugar is a necessity.
The yeast will then sit in the beer for several days, potentially weeks, depending on the style being brewed. As it munches away at the sugar, it is increasing the alcohol content of the beverage while simultaneously lowering the sugar content. Sugar content in beer is know as "Gravity" in the industry. A "High Gravity" beer will start with loads of sugar, ultimately leading to a highly alcoholic beverage.
Eventually, the yeast in the beer will begin to die, as the alcohol content rises. At some point, the yeast will no longer be able to digest the sugars in the beer, and fermentation will cease. Once this happens, the brewers will chill the tank, and then send the beer over to be packaged. Any sugar that is left at this point will end up in the final product.
This is a highly simplified view of the brewing process, but it allows us to understand where the sugar is coming from. Brewer's measure sugar in beer using hydrometer or refractometer.
When a beer is finished fermenting they will use these devices to determine the "Final Gravity" of the beer; that is, how much sugar is leftover. Unless this reads "0.000", there is leftover sugar. As far as beer styles go, most require at least a little residual sugar for flavor.