Study: U.S. Obesity Underestimated
Statistics Often Use Self-Reported Weight & Height, Which May Be Flawed
WebMD News Archive
May 2, 2006 -- Obesity may be more common
that previously thought in the U.S.
In the Journal of the Royal Society of Medicine, researchers note
that national obesity statistics typically rely on self-reported weight and
height, which are often wrong.
Those inaccuracies often make people sound lighter or taller than they
actually are, write Majid Ezzati, PhD, and colleagues. Ezzati works at the
Harvard School of Public Health.
Self-reported weight and height don't always match reality, so U.S. obesity
statistics are too low, Ezzati's team argues.
The researchers recalculated America's obesity statistics, adjusting for
those errors. The result: The nation's obesity estimates went up.
Corrected Obesity Statistics
Obesity is defined as a body mass index (BMI) over
30, according to the CDC.
In 2002, 28.7% of men and 34.5% of women in the U.S. were obese, Ezzati and
The uncorrected estimate for that year indicated that 16% of men and 21.5%
of women were obese.
Ezzati's team based their corrections on data from two large, national
surveys of U.S. adults:
- Behavioral Risk Factor Surveillance System (BRFSS): Given by telephone
- National Health and Nutrition
Examination Survey (NHANES): given in person, with some participants measured
and weighed afterwards
Ezzati and colleagues compared BRFSS and NHANES data for similar years. They
found that people tended to report their height and weight more accurately in
person than over the phone, but that all self-reports generally missed the