There is nothing in the article or studies to justify your point about encouragement. The points raised at the start of the thread are still very valid - who participated in the study and whether there were other important factors which were negleted intentionally or not.

Anecdotal point - I'm fit, it doesn't matter if I drink sugar free soda or water. My calorie intake doesn't change because of that at all. It changes due to other factors like lack of sleep or stress levels.