It's nearly impossible to generalize because every winemaker uses a different "recipe". They harvest their grapes at different stages of ripeness, and they use different kinds of yeast and so on.
That all being said, if you drink an ice wine for example that is VERY high in sugar and calories, so that would be one to avoid
Going by flavor is not a bad idea. So for example a Prosecco sparkling wine from Italy tastes very sweet and is also high in sugar. A Cabernet - red wine - from California does not taste sweet at all and that would be lower in sugar.
Now that all being said, *alcohol* itself is a fuel for your body and has calories. So you want to get the lowest percent alcohol you can in the wine, to reduce those alcohol-provided calories. A wine with 15% alcohol is going to have a lot more alcohol (and therefore calories) than a wine with only 5% alcohol.
So those are the two things to look for. A not-sweet flavor, and a low alcohol number.