More than two thirds of Americans are overweight or obese, with men faring worse than women.
Data from 2007 to 2012 of a nationally representative group of 15,208 people ages 25 or older showed that 40% of men were overweight and 35% obese. Around 30% of women were overweight and 37% obese.
Less than one third of women — and less than one in four men — had normal weight.
Research by Washington University School of Medicine in St Louis is similar to an earlier one by the US Centers for Disease Control and Prevention (CDC) which said that one third of American adults are obese.
Those with overweight were measured by a body mass index between 25 and 29.9. Another 36% of American adults are obese, defined as a having a BMI over 30, says study co-author Lin Yang, a postdoctoral research associate at the Division of Public Health Sciences in the Department of Surgery.
The findings are published in the journal JAMA Internal Medicine.
Obesity-related conditions include heart disease, stroke, type 2 diabetes and certain types of cancer.
The estimated annual medical cost of obesity in the US was $147bn in 2008; the medical costs for people who are obese were $1,429 higher than those of normal weight, says CDC data.
Obesity is a health challenge seen across the globe with change of lifestyles.
A survey by Association for the Study of Obesity in the UK had recently found more than a third of British adults who are obese think they are merely overweight, while a fifth of those who are overweight believe they are healthy.
The group said that seven out of 10 adults are obese in some parts of the UK and the figure could rise by 2030.
According to UK government estimates, the cost of obesity will rise to £50bn by 2053, placing a heavy strain on the National Health Service.