When you drink liquid carbs, like the sugar in soda, your body doesn't register them the same way as, say, a piece of bread, according to a review of studies published in Current Opinion in Clinical Nutrition & Metabolic Care. That means, even though you're taking in calories, your fullness cues aren't likely to signal that you're satisfied once you finish off a can. And that can lead to consuming more overall.
Larson-Meyer, D. E., Willis, K. S., Willis, L. M., Austin, K. J., Hart, A. M., Breton, A. B., & Alexander, B. M. (2013, June 8). Effect of honey versus sucrose on appetite, appetite-regulating hormones, and postmeal thermogenesis [Abstract]. Journal of the American College of Nutrition, 29(5), 482–493. Retrieved from http://www.tandfonline.com/doi/abs/10.1080/07315724.2010.10719885