Lewis Wilson was born on January 28, 1920 in New York City, New York, USA as Lewis Gilbert Wilson. He was an actor, known for Batman (1943), Craig Kennedy, Criminologist (1952) and Wild Women (1951). He was married to Dana Broccoli. He died on August 9, 2000 in San Francisco, California, USA.
During fermentation a lot of the sugar is converted to acid. But there is still more sugar than regular vinegar has. So real aged balsamic vinegar has more calories from the grape sugars.
Just an example. A sweet onion is about 7% sugar, in-which about 40% of that is Fructose. A white onion (or any non-sweet type) is about 5% sugar, in-which less than 40% is Fructose. The amount of Fructose you are getting from even a few ounces of onion is minute. This Fructose is also bound with the flesh (Fiber) and other forms of sugar (Sucrose and Glucose).