A new report shows that the obesity rate in American adults is 42.4% -- the highest rate in history. And get this: The adult obesity rate has increased a whopping 26% since 2008. Childhood obesity is disturbingly on the rise as well. Data revealed that 20% of kids from 2 to 19 are obese. In the 1970s, only 5.5% of children were obese. Mississippi has the highest adult obesity rate in the country at 40.8%. Colorado has the lowest at 23.8% (Eat This, Not That)