Aug. 1, 2012 at 12:14 PM ET
When it comes to their waistlines, many Americans -- especially men -- are in optimistic denial, a new study shows.
Researchers from the University of Washington found that people often think they are losing weight when they really aren’t, according to research published in the August issue of the journal Preventive Medicine.
“People’s weights are going up from year to year,” said lead author Catherine Wetmore, who was a researcher with the Institute for Health Metrics and Evaluation at the University of Washington in Seattle when the new study was written.
“But when they’re asked to think back to a year ago, they recall being heavier than they were,” added Wetmore, who’s now a bio-statistician at the Children’s National Medical Center in Washington, D.C.
The new study was based on surveys of Americans in 2008 and 2009 as part of the Behavioral Risk Factor Surveillance System, or BRFSS. It's the Centers for Disease Control and Prevention's yearly survey of adults in the U.S., designed to track health and lifestyle indicators. For 2008, the study included data from 385,416 participants; in 2009, there were 394,700 volunteers.
For the surveys, volunteers were questioned about their socio-economic status and various health behaviors, including lifetime smoking status, daily fruit and vegetable consumption, and weekly physical activity.
They were also asked about their current weight and the prior year's weight:
“About how much do you weigh without shoes?”
“How much did you weigh a year ago?”
The intriguing part of the new study was the reality check of comparing people’s beliefs about their weight loss to what actually happened in the country as a whole from 2008 to 2009.
As it turns out, many people thought they had slimmed down because they reported their weight as being lower now than it was a year ago.
But when researchers compared the average weight of people in the 2008 survey to the average weight of people answering in the 2009 survey, there was a big disconnect: Over that year, the prevalence of obesity actually increased by half a percentage point. The fact is, on average, Americans had gained a pound.
For that to have happened, people couldn’t have been losing weight from one year to the next, Wetmore concludes.
The people’s recollection of their weights in 2008 sounds fishy.
“They do a lot of rounding up, something we call ‘heaping,’” Wetmore said. “So they report their weight change in increments of 5, 10, 15, or 20 pounds. If they say they’re now 163 pounds and they’re remembering being heavier in the past, they might add 10 to that and say they were 173 pounds a year ago.”
Men appear to be twice as likely as women to inflate the previous year’s weight. Wetmore isn’t sure why that would happen.
“There could be a lot of reasons driving it,” she said. “I know it’s a stereotype, but I think women are more attuned to their appearance. And maybe it’s society’s pressure for women to be thin. Whatever the reason, you do see women doing a better job of keeping track of changes in their weight over time.”
If the weights reported had been true, the prevalence of obesity in the U.S. would have declined from 2008 to 2009. But the scary finding in the study is that the obesity rate among the Americans studied actually jumped half a percentage point, climbing from 26 percent to 26.5 percent.
If researchers had relied on the reports of the volunteers in this study, they would have undercounted approximately 4.4 million obese adults in the U.S., Wetmore noted.
Breaking through America’s weight denial is not an easy task, but it’s a necessary one. What's scary, Wetmore said, is that many people believe they're losing weight when the nation as a whole is getting fatter -- rapidly.
“The message we’re trying to drive home is that if Americans don’t accept the reality of their weight changes over time, they’re not going to be motivated to lose weight,” Wetmore said. “It’s important to be attuned to even small changes in body weight because over time they can really add up.”
Her message to doctors: Don’t let your patients skip the annual weigh-in.
Do you weigh more or less than a year ago? Tell us about it on Facebook.
Related stories on Vitals: