To what extent have sweetened beverages contributed to the obesity epidemic?

OBJECTIVE: A systematic literature review was conducted to determine whether sweetened beverage intake increases the risk for obesity, and the extent to which it has contributed to recent increases in energy intake and adiposity in the USA.
DESIGN: The search included studies published between 1970 and 2010 that examined secular trends, mechanisms, observational associations and intervention outcomes. Observational and intervention studies were abstracted and systematically evaluated for quality.
SETTING: Trends in obesity prevalence in the USA and studies from industrialized (developed) countries were included.
SUBJECTS: Studies were included for all ages, genders, ethnic and socio-economic groups for which data were available.
RESULTS: Obesity rates and sweetened beverage intake have increased in tandem in the USA. Studies consistently show that higher intake of sweetened beverages is associated with higher energy intake. Energy in liquid form is not well compensated for by reductions in the intake of other sources of energy. Well-designed observational studies consistently show a significant positive relationship between sweetened beverage intake and adiposity. More importantly, several well-conducted randomized controlled trials have shown statistically significant changes in adiposity as a result of corresponding changes in sweetened beverage intake.
CONCLUSIONS: All lines of evidence consistently support the conclusion that the consumption of sweetened beverages has contributed to the obesity epidemic. It is estimated that sweetened beverages account for at least one-fifth of the weight gained between 1977 and 2007 in the US population. Actions that are successful in reducing sweetened beverage consumption are likely to have a measurable impact on obesity.