All milk products have sugar, it is called lactose. It is the easiest form of sugar for most people to digest (except for the lactose-intolerant of course). However, some yogurts have more than others, just compare 'light' brands to find the one with the lowest number and you will be fine. Or since you did not dump, the kind you buy might be just fine for you. Lactose does not usually act on a post-op bypasser's system like table sugar does so we can tolerate it in larger amounts, but again it varies from person to person.