Telling a little white lie about your weight isn't so bad, or is it? The results of a new study suggest that if Americans were honest about their self-reported weight, the prevalence of obesity should be on the decline. And if Americans aren't acknowledging their weight problem, what are the chances that they are going to do anything about it?

Researchers from the University of Washington studied data from the 2008 and 2009 Behavioral Risk Factor Surveillance System (BRFSS), an annual phone survey conducted by the Centers for Disease Control. Volunteers were asked about their socioeconomic status, various health behaviors, and they were asked two questions about their weight: "About how much do you weigh without shoes?" and "How much did you weigh a year ago?"

Women seemed to do a better job of tracking their weight than men, as did younger people as compared to older people.

Interestingly, most people said they had lost weight from the previous year, but when the average weight of people surveyed in 2008 was compared to that of people answering the 2009 survey, there was a big difference. The annual prevalence of obesity actually increased from 26 percent in 2008 to 26.5 percent in 2009, or about a pound per American.

In a press release from the Institute for Health Metrics and Evaluation at the University of Washington, Catherine Wetmore, the study's lead author, said, "If people aren’t in touch with their weight and changes in their weight over time, they might not be motivated to lose weight. Misreporting of weight gains and losses also has policy implications. If we had relied on the reported data about weight change between 2008 and 2009, we would have undercounted approximately 4.4 million obese adults in the US.”

The study found that on average people were off by one pound in reporting their weight; people over the age of 50 misreported their weight by more than two pounds, and people with diabetes by four pounds. Women seemed to do a better job of tracking their weight than men, as did younger people as compared to older people.

Not everyone participating in the BRFSS survey reported losing weight. Reports of unintentional weight gain were more common in those who were black, Native American or Hispanic, those who currently or formerly smoked, those who consumed less than five servings of fruits and vegetables a day, those who reported no physical activity, those with chronic diseases, poor mental health, and insufficient sleep, and those who lacked health insurance.

The results of this study suggest that health professionals should use caution when interpreting self-reported weights, particularly when planning, implementing, and assessing programs aimed at weight control. Wetmore's message to doctors is that patients should not be allowed to skip their annual weigh-in.

The study was published in the August 2012 issue of the journal Preventive Medicine.