WASHINGTON (Reuters) - Women who are poor are much more likely to be obese but men are not, U.S. government researchers said on Tuesday in a report that contradicts some common perceptions.

They found income does not greatly affect whether a man is obese but that education seems to affect both sexes.

“Among men, obesity prevalence is generally similar at all income levels, with a tendency to be slightly higher at higher income levels,” the team at the National Center for Health Statistics wrote.

Obesity is a growing problem for U.S. policymakers. Two thirds of Americans are overweight or obese, with 72 million U.S. adults, or 26.7 percent, being obese, with a body mass index or BMI, of 30 or more.

Several studies have linked obesity with both income and education.

The NCHS researchers used data from a national study of 5,000 people that is done every year.

Of the obese adults, 41 percent live in prosperous homes, bringing in at least $77,000 a year for a family of four, or 350 percent of poverty-level income.

They found 39 percent live in homes making between 130 percent and 350 percent of the poverty level, and 20 percent lived in poorer homes with incomes below 130 percent of the poverty level or $29,000 for a family of four.

They found that 33 percent of men living in well-to-do households with income at 350 percent of the poverty level were obese, compared to 29 percent of men who lived below 130 percent of the poverty level.

But income seems to affect a woman’s weight. The researchers found 29 percent of women in well-to-do homes were obese, but 42 percent of women living below poverty level were.

Education plays an important role. Just over 27 percent of men with a college degree were obese compared with 32 percent of those with less than a high school education, while 23 percent of women with a college degree were obese, compared to 42 percent of women with less than a high school education.

A second study found children and teens living in homes with college-educated adults were less likely to be obese, and found stronger associations between obesity and income.

Just under 12 percent of boys and girls living in prosperous homes were obese, compared to 21 percent of boys and 19 percent of girls in the poorest homes.

Body-mass index is the weight in kilograms divided by the square of the height in meters. A BMI of between 25 and 30 is overweight and a BMI of 30 or over is obese.

A person 5 feet 5 inches tall is classified as overweight at 150 pounds (68 kg) and obese at 180 pounds (82 kg). A 5-foot-10 inch (1.8 meter) tall person who weighs 209 pounds (95 kg) has a BMI of 30 and is obese.

Being overweight or obese raises the risk of heart disease, diabetes, some cancers and arthritis and a study published this month in the New England Journal of Medicine confirmed that adults with a BMI of 25 or more are likely to die than someone the same age who is slimmer.