When you're trying to find a low calorie beer you want to key in on two factors: low alcohol levels and high levels of attenuation, a measurement of how thoroughly the yeast consumed the carbohydrates in the beer. The more calories they eat, the less they leave for you to burn off later. The ultimate low-alcohol, high-attenuation beer style is the saison. While many modern saisons have jacked up the alcohol over the years Crooked Stave's Vieille Saison is a throwback to the historical roots of the style with a twist – the addition of a wild yeast called Brettanomyces (Brett).
This yeast ravenously chews through the Vieille Saison's carbs, leaving a lean and light bodied brew with an estimated 105 calories at 4.2 percent alcohol. Brewmaster Chad Yakobsen notes that Vieille is "about as light as a beer can get without using a special enzyme." The main attraction of Brett, though, is the unique flavor and aromas that it imparts in the beer. Get Vieille Saison when it's fresh and it's slightly tart with a nice tropical note. If you're willing to cellar it for a few months to a year that touch of funk will develop and intensify.