Just like the margarita, the classic mojito recipe has been tainted with a reliance on too much sugar or premade mixes. The original recipe is rum, mint, soda water, lime, and just a touch of sugar. Any trusted bartender will do you up right, resulting in a mojito that falls under 150 calories. To be on the safe side, ask the bartender to go easy on the sugar.
Source: Flickr user quinn.anya