Typically, health experts consider adults with a BMI of 25-29.9 to be overweight and those with a BMI of 30 or greater to be obese.
The study, published in the January 6, 2011 research journal Obesity and authored by Peter Katzmarzyk and others at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, only examined white and African American women. There was no similar racial difference between black men and white men. Katmzarzyk theorizes that the weight gap between white and black women may have to do with how body fat is distributed differently throughout the body. What many call "belly fat" is largely recognized as being a significantly greater health risk than fat in the hips and thighs.
Katzmarzyk's findings echo a 2009 study by Dr. Samuel Dagogo-Jack of the University of Tennessee Health Science Center in Memphis. Funded by the National Institutes of Health and the American Diabetes Association, Dagogo-Jack's research revealed that whites had more body fat than blacks, which led him to theorize that muscle mass may be higher in African-Americans.
Existing BMI and WC guidelines are derived from studies of predominantly white and European populations and do not take into account physiological differences due to ethnicity and race. Because of this, Dagogo-Jack believes that his findings "argue for a review of the existing cutoffs for healthy BMI and waist circumference among African-Americans."
Kohl, Simi. "Use of BMI and waist circumference as surrogates of body fat differs by ethnicity." Obesity Vol. 15 No. 11 at Academia.edu. November 2007
Norton, Amy. "'Healthy' waist may be a bit bigger for black women." Reuters Health at Reuters.com. 25 January 2011. Richardson, Carolyn and Mary Hartley, RD. "Study Shows Black Women Can Be Healthy At Higher Weights." caloriecount.about.com. 31 March 2011.
Scott, Jennifer R. "Abdominal Obesity." weightloss.about.com. 11 August 2008.
The Endocrine Society. "Widely Used Body Fat Measurements Overestimate Fatness In African-Americans, Study Finds." ScienceDaily.com. 22 June 2009.