GALVESTON, November 17, 2010 - A startling number of overweight and normal weight women of reproductive age inaccurately perceive their body weight, affecting their weight-related behaviors and making many vulnerable to cardiovascular and other obesity-related diseases, according to new research from the University of Texas Medical Branch (UTMB) at Galveston.
In the December issue of Obstetrics and Gynecology, the researchers report that nearly 25 percent of overweight and 16 percent of normal weight reproductive-age women misperceive their body weight. This is the first study to examine reproductive-age women's weight-related behaviors associated with self-perception of weight.
Overweight and obese Hispanic and African American women are significantly more likely than white women to misjudge their weight, categorizing themselves as normal. The researchers also found that overweight women who perceive themselves as normal weight were significantly less likely to report weight-related behaviors, such as dieting.
"What we found reflects the 'fattening' of America," says corresponding author Dr. Mahbubur Rahman, assistant professor Department of Obstetrics and Gynecology and Center for Interdisciplinary Research in Women's Health. "As obesity numbers climb, many women identify overweight as normal, not based on the scale but on how they view themselves."
Self-perception of body weight is the degree of concordance between perceived and measured weight. The National Institutes of Health defines overweight as having a body mass index (BMI) of greater than 25 kg/m2 - a measurement calculated by dividing an individual's body weight by the square of his or her height (kg/m2). Normal weight is defined as having a BMI of 18.5.9 kg/m2.
More than half of reproductive-aged women in the U.S. are considered overweight or obese by BMI standards, with minority women at greater risk. Currently, 82 percent of African American women and 75 percent of Mexican-American women meet the criteria for being overweight or obese.
Self-perception of Weight and Related Behaviors
The study analyzed more than 2,200 women 18-25 years old based on survey questions pertaining to sociodemographic variables, height, weight, weight perceptions and weight-related behaviors. Women with BMIs below 25 were considered normal weight and those with BMIs of 25 or more were considered overweight. Overall, 52 percent of the study participants were considered overweight or obese.
Using calculated BMI and participants' responses to self-perception questions of weight, the researchers divided the women into four categories: "overweight misperceivers," overweight women who describe themselves as under- or normal weight; "overweight accurate perceivers," overweight women who described themselves as overweight; "normal weight misperceivers," normal weight women who described themselves as overweight; and "normal weight accurate perceivers," normal weight women who described themselves as normal- or under-weight.
Weight-related behaviors assessed included using diet pills, powder or liquids, laxatives or diuretics; induced vomiting; skipping meals; dieting/eating less or differently; smoking more cigarettes; and not eating carbohydrates. Respondents were also asked about the number of days over the last week that they exercised for at least 30 minutes continuously.
Significantly more Hispanic and African Americans - nearly 25 and 30 percent, respectively - were overweight misperceivers compared with white women, 15 percent of whom were included in this category. However, significantly more white and Hispanic women were normal weight misperceivers - approximately 16 and 20 percent, respectively.
Overweight misperceivers had significantly lower odds of participating in healthy or unhealthy weight-related behaviors. Normal weight misperceivers were more than twice as likely to diet, skip meals and smoke more cigarettes; the respective odds were nearly four and five times higher with regard to using diet pills, powder, liquids and diuretics.
These findings were especially concerning, as the lower likelihood of overweight misperceivers to practice healthy weight loss behaviors has a negative impact on obesity prevention, and the higher likelihood of normal weight misperceivers to practice unhealthy weight loss behaviors can lead to harmful medical and psychological consequences.
Self-perception of Weight: The First Step for the Obesity Prevention Ladder
"Weight misperception is a threat to the success of obesity prevention programs," says lead author Dr. Abbey Berenson, professor, Department of Obstetrics and Gynecology and director of the Center for Interdisciplinary Research in Women's Health. "Overweight individuals who do not recognize that they are overweight are far less likely to eat healthfully and exercise. These patients are at risk for cardiovascular disease, type 2 diabetes and other serious problems."
The researchers recommend that clinicians calculate patients' BMI at each visit as part of their vital signs, routinely screen for misperceptions of body weight and inquire about unhealthy weight-related behaviors so that they can counsel patients appropriately.
"This is especially important for reproductive-age women because they are more likely to be obese than similarly aged men, often because they've had at least one child and have not lost pregnancy weight and find that their schedules make it difficult to exercise and eat healthfully," adds Berenson.
Established in 1891, Texas' first academic health center comprises four health sciences schools, three institutes for advanced study, a research enterprise that includes one of only two national laboratories dedicated to the safe study of infectious threats to human health, and a health system offering a full range of primary and specialized medical services throughout Galveston County and the Texas Gulf Coast region. UTMB is a component of the University of Texas System.