What alcohol has no sugar in it?
I don’t know who put you on that diet, but please seek a second opinion, 500 calories per day is not enough energy for an adult to survive on. In answer to your question, all alcohol is sugar. Once the sugar is converted to alcohol by fermentation or distillation the alcohol becomes empty calories. And alcohol replaces sugars in your blood in the form of a substance called acetate. What you are attempting to do is impossible, and if you do stay on the diet DO NOT drink, you will become incredibly drunk quickly and won’t have the energy to process the alcohol through your liver, because you’ve not been ingesting enough sugars or carbohydrates. I work in the wine industry… and love a drink. But what’re you’re describing here sounds unsafe.