In 1985, the National Institutes of Health convened a consensus conference on the health implications of excess body weight (obesity).The conference concluded excess weight, defined as 120% of desirable weight,constitutes a significant risk factor for several chronic diseases including coronary heart disease, hypertension, and cancer. These effects increase both morbidity and mortality among overweight individuals.  Twenty-seven percent of U.S. women and 24% of U.S. men are overweight.  Once individuals become overweight remediation is difficult, and efforts to lose weight may be as or more harmful than the condition itself. Prevention, rather than remediation,is the most desirable and, perhaps the only practical, safe way to significantly decrease the number of overweight persons.
While chronic disease outcomes related to obesity usually are not manifest until adulthood, behaviors that predispose individuals to obesity often are established during adolescence. As many as 70% of overweight adolescents become overweight adults.  Researchers estimate 15% to 30% of U.S. adolescents may be overweight.  Gortmaker et al analyzed trends in adolescent obesity from 1963 to 1980 using data from four surveys of the U.S. population. During that period obesity increased 39% for the population; 35% for Whites and 53% for Blacks. Gortmaker et al estimated the prevalence of obesity for 12-17 year olds at 18% for males and 26% for females.
Increases in the prevalence of obesity among adolescents pose negative implications, not only for long-term health risks, but for immediate physiological and psychological well being. Obesity, the leading cause of sustained hypertension in adolescents, has been linked to orthopedic disorders and diabetics. The increase in adolescent obesity occurred despite a cultural standard that encourages thinness. Thus, adolescents, particularly females, often hold a concept of attractiveness that does not conform to reality. In a study on teen-age nutrition and physique, Huenemann et al reported as many as 70% of adolescent girls were dissatisifed with their bodies and wanted to lose weight. Moore found 67% of adolescent girls were dissatisfied with their weight. Of the 63% who believed they were overweight, only 40% actually were overweight. Storz and Green also found a high prevalence of dissatisfaction with body size among adolescent girls; 62% of girls who desired weight loss actuary were within the normal weight range.
When reviewing weight loss methods used by adolescents ages 14-18, Storz and Green found exercise the most popular method, followed by low-energy crash diets. Of adolescents attempting to lose weight, 41% used undesirable methods such as fasting or diet pills. Dieting by young women of normal weight could pose a threat to nutritional status and predispose them to later eating disorders. One study of adolescent girls in grades 9-12 reported vomiting rates of 11.2% and laxative use rates of 4.7%. Bulimics often report their bulimia began in adolescence and was associated with attempts to lose weight
The positive relationship between adolescent and adult obesity, combined with the immediate negative impact of obesity on physical and psychological health status, prompted the U.S. Public Health Service to target adolescent obesity in Healthy Youth 2000: National health promotion and disease prevention Objectives for adolescents specifically the goal seeks to reduce the prevalence of obesity to no more than 15% among individuals ages 12-19. To accomplish this goal the complex etiology of adolescent obesity must be better understood. Genetic factors influence body weight as do organic factors. Black women, for example, are more likely than White women to be overweight. An ethnic differential also exists in mortality rates with overweight Black women recording higher death rates from coronary heart disease, stroke, diabetes, and hypertension than overweight White women. Caloric balance represents a critical factor in weight gain. Obese adolescents consume no more calories than their normal weight counterparts. Obese adolescents are, however, less active and demonstrate lower levels of physical fitness.
Television has been cited as a factor in a sedentary lifestyle - weight gain cycle in adolescents. Dietz and Gortmaker report U.S. children spend as much time watching television each year as they do attending school. The average family watches more than seven hours of television per day. Watching television requires no energy in excess of resting metabolic rates, may decrease time spent in energy-expensive activites, and may increase between-meal snacking. For adolescents ages 12-17, Dietz and Gortmaker found a significant association between time spent watching television and the prevalence of obesity, with the prevalence of obesity increasing two percent for each additional hour of television viewed. Tucker reports adolescents who often watch television expend less energy than do less frequent viewers and they are less physically fit.
This study examined perceptions of relative weight and the relationship of these perceptions to physical activity levels, time spent viewing televsion, and efforts to lose weight among public high school students in North Carolina.
Instrumentation Data were collected as part of a larger study of health risk behaviors of North Carolina public school students using a modified version of the Youth Risk Survey (YRBS). The instrument was developed by the Division of Adolescent and School Health, Centers for Disease Control to assess important health behaviors among youth which contribute most significantly to adverse health outcomes. Potential risk areas addressed in the original survey included behaviors resulting in intentional and unintentional injuries; drug and alcohol use; tobacco use; sexual behaviors that result in HIV infection, other sexually transmitted diseases, and unintended pregnancies; dietary behaviors; and physical activity. Due to potential difficulty in obtaining local clearance, questions about sexual behavior were deleted from the modified YRBS, resulting in an instrument with 61 questions.
Participants The modified Youth Risk Behavior Survey was administered to students in ninth grade science classes and 12th grade English classes during May 1990. Classes were contained in schools randomly selected from lists of all public schools containing any ninth grade or 12th grade. This procedure resulted in 107 schools being selected for the ninth grade sample and 101 schools for the 12th grade sample. These schools received instructions regarding procedures for random selection of classes within their respective schools. Overall response rates accounting for nonparticipating schools and unusable response forms were 55% for the ninth grade sample and 56% for the 12th grade sample. Results reported here are based on the combined data set (ninth and 12th grade samples) containing responses from 3,437 students. Respondents were 46.9% males (72.2% White, 23.1% Black, 4.7% Other) and 53.1% females (67.4% White, 26.9% Black, and 5.7% Other).
RESULTS When students were asked how they perceived their current weight, 25% (N = 836) reported they were "too fat." The gender difference in weight perceptions was significant [[X.sup.2](1, N = 3,287) = 149.30, p < .001] with females (34.6%) being more likely, than males (15.6%) to report being "too-fat." Whites (27.2%) were more likely than Blacks (20.5%) to perceive themselves as being "too-fat" [[X.sup.2](1, N = 3,287) = 15.44, p < .001]. White females (37%) were more likely to view themselves as being overweight than Black females (27%). Of 836 students who viewed themselves as being "too-fat," 70% (N = 582) were trying to lose weight. Females made up 75% of those reporting they were "too-fat" and trying to lose weight and were more likely to be trying to lose weight than males [[X.sup.2](3, N = 836) = 24.00, p < .001], 7;3.3% vs. 60.4%, respectively. Whites (72.3%) were more likely than Blacks (60.1%) to be trying to lose weight [[X.sup.2](3, N = 836) = 11.73, p < .008]. Figure 1 characterizes the weight management activities of those individuals who perceived themselves as being "too-fat."
Students reported dietary practices in which they had participated during the past seven days to lose weight or to keep from gaining weight. Sixty-three percent who felt they were overweight had skipped at least one meal (Figure 2), 5% had taken at least one diet pill, and 5% had vomited at least once during that period. Whites were more likely to have skipped a meal than Blacks [[X.sup.2](4, N = 580) = 16.83, p < .002], but no significant ethnic differences existed regarding diet pill use or vomiting incidence. Analysis of dietary practices for weight loss/maintenance by gender showed females significantly more likely than males to skip meals [[X.sup.2](4, N = 579) = 21.40, p < .001] and more likely to take diet pills. [[X.sup.2](1, N = 582) = 9.17, p < .010].
Students were asked "During the past seven days, how many times did you exercise to lose weight or to keep from gaining weight?" Whites were more likely to have exercised to lose weight or to maintain their weight. Females were more likely than males to exercise in the light to moderate range; 60% exercised two or fewer times during the past week. Males were more likely to exercise in the moderate to heavy range with 53% exercising more than three times during the previous week (Figure 3).
Adolescents who perceived themselves as "too-fat" reported fewer days of strenuous activity [[X.sup.2](4, N = 3,425) = 46.16, p < .001] and fewer hours of stenuous exercise in physical education classes [[X.sup.2](4, N = 3,364) = 32.35, p < .001] than adolescents who perceived themselves as too thin or about the right weight. Adolescents who did not view themselves as being "too-fat" were more likely to exercise hard when compared to those who perceived themselves as being "too fat." Adolescents who perceived themselves as "too-fat" also spent more hours viewing television on school days [[X.sup.2](5, N = 3,403) = 32.74, p < .001] than others. A greater proportion of those who perceived themselves to be "too fat" viewed television or played video games for four or more hours per day; 27% and 19%, respectively (Figure 4).
DISCUSSION The major limitation in interpreting results from this study involves the fact that actual body weight and/or body composition were not determined for subjects. Previous research indicated differential accuracy of perceived weight as a function of both gender and ethnicity.[11,14] The percentage of adolescents who perceive themselves as overweight (25%) is consistent with national estimates for the adolescent population. Also consistent with previous research is the greater percentage of females, particularly White females, who perceive themselves as overweight. Many variables influence how adolescents perceive themselves and whether or not they are satisfied with that perception. In addressing adolescents, health educators should consider these factors and try to help them distinguish between healthy weight standards and the unrealistic standards often held by this age group. Billions of dollars are spent annually on cosmetics, physical fitness, and weight reduction advertising with messages encouraging thinness. Adolescents are more strongly influenced by their weight relative to their peers than to an arbitrary, health-based standard. Potentially, adolescents with distorted perceptions of weight may set unrealistic goals and adopt unhealthy behaviors to regulate their weight. Adolescents need assistance in determining their appropriate and healthy weight.
Research indicates Black adult women are more likely to be overweight than White women or men of either ethnic group. They are, however, less likely to view themselves as being overweight because it is culturlly acceptable. Similar patterns emerged in the adolescent sample. Black females were less likely than Whites to perceive themselves as overweight. Among females who perceived themselves as overweight, Blacks were less likely to be trying to alter their weight. This finding is of particular concern given the elevated levels of obesity-related disorders including hypertension in this population. While genetic differences probably play some role in the development of obesity, sociocultural and economic factors are likely as important in its development. Sociocultural influences are central to the disparate perceptions of appropriate weight between Whites and Blacks. To successfully encourage behaviors that prevent development of obesity, health educators should identify specific factors influencing normative weight perception and develop programs to target them.
Haywood indicated "adolescence is the time students begin to have more control over how they spend their time." Whether or not they choose to spend their time actively engaged in physical activity may prove a critical factor in becoming overweight and eventually obese. These findings lend support to this premise. Adolescents who perceived themselves as too fat were less likely to report participating in physical activity either in or out of school. These results also support previous researchers who concluded a positive correlation existed between time spent watching television and prevalence of obesity in adolescents. Those who spend many hours watching television each day expend less energy than do occasional viewers and tend to be less physically fit. Insufficient physical activity has been cited as a contributor to heart disease. With the growth in popularity of cable TV, video games, and home-video recording, television viewing likely will continue to increase. Tucker and Bagwell reported adult females who watched three to four hours of television per day were twice as likely to be obese than those who watched one hour or less. The correlational nature of this study does not allow for causative conclusions regarding the relationship between perceived fatness and sedentary lifestyle. These data coupled with those linking television viewing to greater consumption of so-called "snack foods" do lend credence, however, to the importance of lifestyle factors as contributors to adolescent obesity.
If school-based programs are to assist reducing adolescent obesity, traditional barriers between health education and physical education as well as barriers existing between school and community must be removed, particularly in an environment where prescribed physical activity for adolescents through required physical education is becoming less common. Educators must use an integrated, public health approach that encourages adolescents to adopt active lifestyles. This approach requires development of skills in activities that require relatively high levels of caloric expenditure and creation of an environment that encourages participation in such activities. Creation of an environment supportive of and conducive to physical activity presents significant challenges in the face of cultural norms that encourage sedentary behaviors. This problem is compounded by the time constraints on current school-based programs. The challenge will be met only when schools, parents, and communities work collaboratively to provide opportunities and incentives for all adolescents to engage in both school-based and extracurricular physical activity.
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Michael Felts, PhD, Associate Professor, Health Education; Debra Tavasso, BS, Graduate Assistant, Health Education; Thomas Chenier, PhD, Associate Professor, Biostatistics; and Patricia Dunn, PhD, Professor, Health Education, East Carolina University, Greenville, NC 27858. This project was supported by cooperative agreement # U63/CCU403072-02 with the Division of Adolescent and School Health, Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control, Atlanta, GA. This article was submitted December 9, 1991, and accepted for publication March 16, 1992.…