Obesity rates have swelled again in America, bleak new figures reveal.

Researchers were heartened by news that child obesity remains relatively unchanged over the past decade - although the staggeringly high figure is not decreasing.

But since 2007, adult waistlines have been steadily expanding with no signs of letting up, particularly among women.

The overall rate of obese adults climbed from 33.7 percent in 2007 to 39.6 percent in 2016, according to a nationally representative study of 40,000 people.

That includes 37.9 percent of men (up from 32.2) and 41.1 percent of women (up from 35.4).

Meanwhile 7.7 percent of Americans are morbidly obese - 9.7 percent of women (up from 7.3) and 5.6 percent of men (up from 4.2).

While researchers were heartened by news that child obesity remains relatively unchanged over the past decade, adult waistlines have swelled uncontrollably

CDC analysts, who had expected to see a plateau, said the disheartening findings show public health campaigns to curtail the obesity crisis - and the related rise in diseases - are not resonating with the American people.

Obesity, measured as a body mass index over 30, and severe obesity, BMI over 40, has been on the rise since the 1980s.

However, national survey data showed a plateau among young people between 2005 and 2014.

Those blips led researchers to investigate whether it was part of a broader trend.

Unfortunately, that was not the case.

Just over seven percent of Americans are morbidly obese - 9.7 percent of women (up from 7.3) and 5.6 percent of men (up from 4.2)

A team at the CDC led by Craig M. Hales, MD, analyzed data from 16,875 Americans under 19 and 27,449 adults from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2016.

Obesity rates remain unchanged in young people, but the increase among adults is worrying.

Nearly half of the women in the survey were obese by 2016, and well over a third of men.

The figures come just days after a report showed the US has the fattest male population in the world.

American men weigh an average of 196lbs, while Australian men come in at 189lbs, and Brits weigh around 186lbs.

The findings mirror a report issued in November, which saw the US top the Organisation for Economic Co-operation and Development's league of overweight nations.