There is a great thread on this in the general low carb section, do a search there. It is also talked about in the book 500 Low-Carb Recipes. Basicaly the live active cultures in the yogurt turn the lactose to lactic acid, this gives yogurt it's slightly bitter taste. Lactose is the milk sugar. When it is eaten, the actual amount of effective (or net) carbs in yogurt is reduced to 4 per cup. You have to find a good yogurt though with plenty of cultures. The yogurt also helps the good bacteria in the intestines which is great for people with yeast over growths.

Yogurt can effect people differently. I only have a half cup per day and count all the carbs on the nutricional lable, even though I know I'm not getting all those. You can probably safly add it back in as soon as you go to OWL if you feel comfortable trying it. If you are lactose intolerent and not having any cream while on induction, you might try using it in place of the cream in some recipes. There are more carbs that have to be counted, but it means no upset tummy for me