I should probably go read the full article to find out if they tried unsweetened fruit juice too (need to leave for work soon, so I just don't have time right now), but it would be interesting to find out if there was any difference at all between a sugar sweetened drink, and the same number of calories from fruit juice. I'd be very surprised if there was a difference, much less a statistically significant difference between the two.

Or how about comparing it to skim milk, to see if there's some way in which the presence of protein bound to the same number of calories from lactose in the milk (ETA: as opposed to being a separate component of the meal) makes any kind of difference.

And yes, it'd be interesting to know the results with artificial sweeteners too.