A growing body of research indicates that diet, rather than exercise, is the key to developing or maintaining a healthy weight. Despite Coca Cola's best efforts to portray physical activity as an adequate mitigator to unhealthy eating habits, experts increasingly believe that few people are realistically able to exercise enough to make up for the bad food they're eating. 

The newest study demonstrating the limitations of physical activity found that the calorie-burning effect of physical activity declines the more one exercises. That means that a five-mile run does not necessarily burn five times as many calories as a one-mile run. 

"Our bodies adapt to higher activity levels so that people don't necessarily burn extra calories even if they exercise more," Herman Pontzer, the study's lead author and a professor of anthropology at City University of New York, told CBC News.