Between 2000 and 2010, the proportion of Americans who were severely obese, at least 100 pounds overweight, rose from 4 percent to almost 7 percent.
Although the increase has slowed a bit, researchers say the trouble is the severely obese remain the fastest-growing segment of obese Americans.
The new findings come from the non-profit research institute rand corporation.
Other studies have found the nation's obesity rate may be leveling off.
But most of those people are moderately obese.
