Objective: Some studies have shown that abdominal obesity may be a better predictor than overall obesity for disease risks and all-cause mortality. This study sought to examine the recent trends in waist circumference (WC) among adults in the United States.
Research methods and procedures: Data from the National Health and Nutrition Examination Survey during 1988-1994, 1999-2000, 2001-2002, and 2003-2004 were analyzed to estimate the trends in the mean WC and the prevalence of abdominal obesity. Pooled t tests were used to test the differences in estimates between two time periods.
Results: Between the periods of 1988-1994 and 2003-2004, the age-adjusted mean WC increased from 96.0 cm to 100.4 cm among men (p < 0.001) and from 89.0 cm to 94.0 cm among women (p < 0.001); the age-adjusted prevalence of abdominal obesity increased from 29.5% to 42.4% among men (p < 0.001) and from 47.0% to 61.3% among women (p < 0.001). Between the periods of 1999-2000 and 2003-2004, a significant increase occurred in mean WC only among men (from 99.0 cm to 100.4 cm; p = 0.03) and in the prevalence of abdominal obesity among both men (from 37.0% to 42.2%; p = 0.03) and women (from 55.3% to 61.3%; p = 0.04). People with a BMI of 25 to 29 kg/m2 had a greater relative increase in abdominal obesity.
Discussion: The mean WC and the prevalence of abdominal obesity among U.S. adults have increased continuously during the past 15 years. Over one-half of U.S. adults had abdominal obesity in the period of 2003-2004.