Why is obesity more prevalent in America now than it was 25 years ago? Ask that question to anyone you know, and their answer will likely include an explanation of how Americans are eating more now than we were then. But is there is another side to the equation? Is it possible that America’s collective weight gain has been due to a decrease in physical activity, rather than an increase in calorie intake? A new study published in The American Journal of Medicine (Ladabaum, et al, 2014) suggests that very idea, finding that while our calorie intake has remained the same over the last two decades, our physical activity has plummeted, factors that are positively associated with increased obesity.