According to a new RAND Corporation study, Americans who are severely obese (100 pounds or more overweight) increased about 70 percent from 2000 to 2010.
During those ten years, severely obese Americans rose from 3.9 percent of the population to 6.6 percent, reports ScienceDaily.com.
The study, which was published online by the International Journal of Obesity, said that 15 million adult Americans are morbidly obese with a body mass index of 40 or more.
However, in 2005, the growth of the severely obese Americans began to flatten out.
Roland Sturm, lead author of the study and a senior economist at RAND, told ScienceDaily.com: "The proportion of people at the high end of the weight scale continues to increase faster than any other group of obese people, despite increased public attention on the risks of obesity. But for the first time in the past 20 years there is evidence the trend is slowing."