As with all dairy products, the higher the fat content, the lower the carb content. So, buy plain unsweetened yogurt with the highest fat % you can find. Here in Canada, whole milk yogurt is 3.2%, and has 6g per 1/2 cup serving. If you can find it, Greek or Balkan-style plain yogurt is 5% fat, and has 5g carbs.

The skim milk and lowfat yogurts have 7 to 9g carbs per 1/2 cup serving.

Check the ingredient list ... some brands call it "plain" and even so, they put sugar in it

I use either Greek or organic yogurt in place of sour cream. Most commercial sour creams contain modified cornstarch and vegetable gums to make them thick .. and they end up being the same carb counts (1.5 to 2g per 2 Tbsp serving).

Doreen