The question of whether sugary drinks contribute to obesity is controversial, not least because the large manufacturers of the drinks would most likely suffer if the contribution to obesity were proved.
Michael Bloomberg, the recent Mayor of New York believed the problem so serious he tried to impose bans and taxes on some drinks in an attempt to fight flab in the city (see NYT stories here and here. The industry disagreed with his position arguing that soft drinks were irrelevant to obesity:
"The New York City health department’s unhealthy obsession with attacking soft drinks is again pushing them over the top,” the industry spokesman, Stefan Friedman, said. “It’s time for serious health professionals to move on and seek solutions that are going to actually curb obesity."
Given the controversy, what does the balance of evidence look like? Do sugary drinks contribute significantly to obesity?
NB I think answers should avoid the meaningless distinction between sucrose and High Fructose Corn Syrup (HFCS) as the difference is negligible when ingested.
Also note that related, but not identical, questions have been asked here before such as: Can artificial sweeteners make you gain weight?