toasty

I don't know that I have ever heard anyone indicate the maximum grams of sugar per day. And I know that not all sugar is created equal, so to speak. Generally, sugar found in milk (lactose) is not as much of a problem as say table sugar or high fructose corn syrup, so I wouldn't worry about the sugar in Nonfat Greek yogurt. Other yogurts may have added sugar, though. Also, although fructose and sucrose can be a problem, in fruits with a high level of Fiber (such as apples, for example) the sugar is not really a problem. So the answer seems complicated, and I don't really think there is a simple "no more than X grams of sugar" answer. Generally, I follow the rule of very little ADDED sugar, or very little sugar from low-fiber products.

...and there's always someone ready to sell them that answer! Whether or not it is snake oil.