It probably comes as no surprise that most athletes stay away from sugar-sodas.
High in simple carbohydrates, they add nothing to the dietary equation except hollow calories and they stop fat-burning in its tracks due to the spike in insulin that results from drinking pure sugar.
If that's not enough, 130,000 cases of diabetes have been linked to sugar soft drinks.
Take a look: http://www.naturalnews.com/028340_diabetes_sodas.html
FYI: The leading cause of death in Mexico is diabetes. Interestingly, Mexico also has the highest per capita consumption of sugar-based soft drinks. Connection? I think so.
Train hard; diet harder.