The higher waist size of Americans posed more risk compared to their English peers across most body mass index categories. For example, among women with normal weight, 41 percent of American women were categorized as having high waist risk compared to 9 percent of English women.

The study concludes that waist circumference explains a substantial proportion of the higher diabetes rate in America for men and virtually all the higher rate seen among women.

Researchers say there may be many reasons why Americans have larger waists than their English peers. It may be caused by different rates of physical activities through exercise or daily activities, diet differences or perhaps other social and environmental factors such as stress that occur in the United States.

Researchers say that future research needs to address the different mechanisms that may be responsible for this association. For example, there is evidence that fat in the midsection has a different metabolism than fat carried elsewhere on the torso.

Researchers say that past evidence has shown that waist circumference is a better marker for visceral fat than other measurements. Previous studies have shown that fat cells located in a person's midsection have specific dysfunction that may be involved in the mechanisms that lead to diabetes.

The research was supported by a grant from the National Institute on Aging and was conducted through the RAND Labor and Population program. The program examines issues involving U.S. labor markets, the demographics of families and children, social welfare policy, the social and economic functioning of the elderly, and economic and social change in developing countries.

Source: RAND Corporation