The rising obesity during the past three decades poses a severe public health challenge and spurred enormous research interests. This paper contributes to the growing literature on how obesity spreads by empirically investigating whether social norms affect soft drink consumption choices. Combining market level soft drink scanner data and survey data with consumer level characteristics, we employ reduced form regressions to test whether social norms of body weight affects per capita consumption of total or caloric soft drink consumption, on a market level. We also utilize a random-coefficient logit model to examine whether social norms of body weight affect consumer choices on a brand level. Our results from the market level analyses support that a heavier socially normal body weight leads to more average total consumption of soft drink and caloric intake from soft drink, suggesting a social multiplier effect. The results from the brand level choices are less clear at this point.