In reply to Pj84:
It's fairly easy to get to grips with this.
The main source of calories in booze is the actual alcohol itself. Your body breaks this down into sugars. It works out very roughly at 55-66 calories (kCal really) per unit.
Other constituents in the drink then make up the remainder of the calories. If you pour a sugary mixer in there, it will add up fast, just as drinking the same soft drink on its own would be a bad dietary choice.
Beer does have some calories in the form of sugars, but these are generally heavily outweighed by the alcohol itself.
'Clean' choices that make the counting easier include spirits with zero-cal mixers, as suggested above in various forms. Dry white and red wines are generally a good call too; the vast majority of wines have all of the sugars fermented out (any apparent 'sweetness' is a combination of other flavours and the alcohol working together).
Beer might not actually be a bad choice, since the sheer volume of liquid often encourages moderation in terms of units. But if you're drinking 8 pints a night, then, well, a bottle of wine may be a better call...
