More than two thirds of all Americans now obese or overweight

A majority of Americans are either obese or overweight, a major new study has found, showing an increase of more than 10 per cent since the 1990s.

The new figures also show that the number of obese people outweighs those who are merely overweight for the first time.

Researchers from Washington University School of Medicine in St Louis studied data on more than 15,000 men and women aged 25 or older of a nationally representative group collected between 2007 and 2012 as part of the National Health and Nutrition Examination Survey.

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The researchers were able to estimate that 67.6 million Americans over the age of 25 were obese in 2012 and a further 65.2 million were overweight.

"We see this as a wake-up call to implement policies and practices designed to combat overweight and obesity, to implement what we already know into place to accelerate the obesity prevention and treatment," Lin Yang, a postdoctoral researcher in the Division of Public Health Sciences at Washington University School of Medicine, told CBS News.

A typical 'all you can eat' buffet, USA (Alamy)

"Population-based strategies may help to alter the obesity trend through physical environment interventions, enhancing primary care efforts, and shifting society norms of behaviour."

The new data follows on from a major survey between 1988 and 1994 that brought the issue of obesity into sharp focus.

The survey, published in JAMA Internal Medicine, showed that 75 per cent of men and 67 per cent of women ages 25 and older are now overweight or obese.

This compares with 20 years ago when 63 per cent of men and 55 per cent of women were overweight or obese.

There have been several high profile attempts to tackle the problem of obesity, such as Michelle Obama’s Let’s Move campaign.

However, the new figures show that the issue of obese and overweight Americans is a growing problem.