Am I fat? Many of today's adolescents don't think so

"Adolescents with accurate self-perceptions of their body weight have greater readiness to make weight-related behavioral changes and are more effective in making the changes," explained lead investigator Jian Zhang, MD, DrPH, from the Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro GA. "By contrast, overweight adolescents who do not perceive their weight status properly are less likely to desire weight loss, and are more likely to have a poor diet."

When dealing with self-perception, many factors may come into play. For example, as obesity prevalence has more than doubled in adolescents during the past 20 years, socially accepted normal weight may also be shifting accordingly. "In the wake of the obesity pandemic, the media, weight loss industries, and medical communities have encouraged adolescents to maintain slender frames. Facing harsher messages, more and more overweight and obese adolescents may be increasingly reluctant to admit that they are overweight," noted Dr. Zhang.

Researchers used data from adolescents aged 12-16 years who participated in the National Health and Nutrition Examination Survey (NHANES) in 1988-1994 ("early," n=1,720) or 2007-2012 ("recent," n=2,518). The self-perception of the participant's weight was obtained from the Youth Questionnaires in the early survey and the Weight History Module in the recent survey. In both surveys, the respondents were asked: Do you consider yourself to be overweight, underweight, or just about the right weight? Participants were categorized as obese, overweight, or normal weight using body mass index (BMI) scores.

The study determined that after adjusting for age, race/ethnicity, sex, and family income, the probability of self-perceiving as "overweight" declined by 29% for overweight/obese adolescents interviewed during 2007-2012 compared with adolescents interviewed in 1988-1994. This misperception was most pronounced among whites and least among blacks.

The researchers also suggest that the Social Comparison Theory may provide an additional explanation. According to this theory, individuals compare themselves to others, rather than to some absolute scale. With more overweight friends, adolescents may have a more positive image of their own weight.

Further contributing factors are that adolescents in general experience significant changes in body appearance as they progress through puberty and the definitions of overweight and obese have changed over time.

Nevertheless, Dr. Zhang and co-investigators caution that, "Becoming conscious of one's excess weight is the precursor to adopting behavioral changes necessary for appropriate weight control. The declining tendency of correctly perceiving overweight status presents a vast challenge to obesity prevention among adolescents, making the overweight and obese adolescents less motivated to actively engage in effective weight loss behaviors." On the other hand, the increasing proportion of overweight adolescents self-perceiving their body weight as the right weight may suggest a reduction in social pressure on adolescents and less psychological distress among adolescents to maintain lower weights. The researchers call for novel strategies to delicately protect adolescents' attitude towards body image while correcting the body misperception to motivate adolescents.