"Yes.. sugar does in fact have calories and amazingly those drinks have their calories and sugar content listed on them.. "
Yes, it's just thermodynamics! Except that it isn't because there's
a human being in the loop acting as a control system, and so
there are complicated psychological and physiological effects
going on that no one seems to understand terribly well.
Are high carbohydrate diets bad? Then how do you explain the Japanese?
Are high fat diets bad? Then how do you explain the French?
Could it be that sugar is a particularly bad form of
carbohydrates? Well sure it could be... but if all you've got is
an argument from correlation (sugar intake up => obesity rate up)
then you don't actually know much, because it could easily be something
more complicated (economy up => sugar intake up plus economy up
=> gasoline intake up).
In conclusion: (1) Shit is complicated. Don't believe anything
but a full lifestyle, cross-cultural comparison, (2) What you
shove in your mouth matters less than if you get off of your butt,
(3) "We need more willpower" isn't a solution or there wouldn't be
a problem. Kill your automobile.