Yay? In 2012 the national prevalence of obesity, defined as a body mass index of greater than 30, was 30 percent. Of the 50 states and the District of Columbia, Alaska had the 14th lowest rate at 25.7 percent. The three worst states were - no surprise - in the south: Louisiana, Mississippi and Arkansas all at just under 35 percent. Colorado was the best at 20.5 percent, followed by DC, Massachusetts, Hawaii and New York.