One way to visualise alcohol calories is to see it has has roughly the same amount as oil 5-9cal/ml. So 500ml of 5% lager alcohol contributes roughly the same as 25ml of oil, ~200 calories. And in a 75ml bottle of, say, 12% wine alcohol contribute about as much as 90ml of oil, 700 calories.
This high level should not be too surprising, given that alcohol is manufactured from sugar, again roughly the same order of calorie density. Part of Victorian doctors’ mistaken enthusiasm for prescribing alcohol was it provided weakened invalids with a “clean” source of energy.
It’s by no means perfectly accurate, but it is a reasonable way to get a feel for it, in the absence of clear labelling. ■