No, no, no !!
No, no, no !!!!
The obesity epidemic is fundamentally down to over-consumption, and under-excercise...
...in combination with a huge increase in the use of High Fructose corn-syrup, endemic 'go large' meals, much wider availability of snacking, industrialization of food production, an industry obsessed by the saleable fad of low-fat to the detriment of over-all calorie intake etc... and a sedantry lifestyle.
Anything else is window dressing.
Which has more sugar ?
250ml Smoothie
330Ml can full sugar soda ?
The smoothie, with about 8 teaspoons worth of sugar.
Though if you had a water or no-added sugar or no-sugar drink, it would be next to zero.