The majority of the calories come from the FG, not the alcohol. Low mash temperatures (or other ways of getting the fermentability very high) mean very low FGs and thus low calorie beer.
And yes, 129 calories for 12 oz is a very low cal beer, all things considered. I think I've made one that topped 500. ;D
And yes, 129 calories for 12 oz is a very low cal beer, all things considered. I think I've made one that topped 500. ;D