About four million American adults -- or one in every 50 adults -- are extremely obese, tipping the scales over by at least 45 kilograms or more.
The finding by Roland Strum, a RAND Corp researcher, also shows the number of extremely obese Americans have quadrupled since the 1980s.
Conventional thinking suggested that extreme obesity was a rare condition whose prevalence remained relatively steady over time.
But the new study contradicts that thinking and suggests that extreme obesity is at least partly due to overeating and under-activity.
The findings also show that the number of extremely obese adults in the US has surged twice as fast as the number of less severely obese adults.
"On the scale of obesity, as the whole population shifts to the right, the extreme categories grow the fastest," Sturm told a news agency. "These people have the highest health care costs."
Sturm said health problems associated with obesity included diabetes, heart disease, high blood pressure and arthritis.
Agencies
© 2025