Adolescents Background - NCS Dietary Assessment Literature Review

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"Within any 24-hour period in the life of a teenager, eating may be a positive or a negative experience. It may involve a quick snack or a grazing process. Eating for teens may be a group decision, an interaction, or an independent endeavor. The experience can vary greatly from teen to teen and for any one teen. Inter- and intravariability may be great. Conversely, eating may be a consistent, uneventful pattern hour-to-hour or day-to-day." Gail C. Frank, 1997 (219)

For this report, the adolescent age group includes children ages 13 to 18 years, although adolescence is often defined as encompassing from 11 through 21 years (251). During adolescence, children undergo profound biological, emotional, social, and cognitive changes to reach adult maturity. They experience the physical transformation into young adulthood and must psychologically adjust to a new body that has changed in shape, size, and physiological capacity. At the same time, adolescents are striving to attain a unique identity and value system separate from parents and other family members as well as personal independence, while still needing financial and emotional support from family members.

Adolescent needs for energy and all nutrients significantly increase to support the rapid rate of growth and development; as much as 50% of adult ideal body weight is gained in adolescence (251). Although appetite and food intake increase, the struggle for independence that characterizes adolescent psychosocial development often leads to the development of high-risk nutritional behaviors such as excessive dieting, meal skipping, use of unconventional nutritional and non-nutritional supplements, adoption of fad diets, and excessive alcohol consumption. The high prevalence of overweight and obesity, eating disorders, adolescent pregnancy, and the lack of consumption of five fruits and vegetables a day are among the challenging nutritional issues facing adolescents in the United States (219;251).

Exhibit 5.1 (in the School Age Children section) highlights differences in dietary assessment methodological issues between school age children and adolescents. A number of factors contribute to the challenge of collecting valid dietary information from teenagers.

• Rapidly changing eating habits. The eating habits of adolescents are not static; they fluctuate throughout adolescence in relation to psychological and cognitive development and to growth and appetite changes.
• Unstructured eating. Snacking and meal skipping are routine; "Grazing" is commonplace and teens may have "sneals" and not just snacks and meals (219).
• Peer influence exceeds parental influence. Eating away from home becomes prevalent, and fast-food accounts for 31% of food eaten away from home (218); only one-third of middle-class US 14 year olds eat dinner with their family on most days (239).
• Age related compliance. An overall trend toward an increase in energy underreporting with increasing age has been documented with DLW (Doubly Labeled Water) studies in adolescents (161).
• High prevalence of restrained eating. The well documented high prevalence of dissatisfaction of many normal weight adolescents with their weight has implications for bias in dietary surveys; inclusion of measures of dietary restraint and body image is important in this age group (161).
• Overweight and obesity may lead to underreporting of intake. As with obese adults, obese adolescents underreport intake significantly more than their non-obese counterparts; up to 40% of energy intake in obese adolescents may not be reported (195).
• Dietary assessment probing, coding, and reporting formats designed for adults do not adequately reflect the eating patterns of teens. Dietary assessment methods should address the eating environments and patterns of teens as well as capabilities and motivation at different stages of adolescence (161;218;219).
• Research in school settings is difficult. Increasing time pressures on school curriculum limit time for recruitment and adequate explanation of study forms and procedures; alternative approaches and locations that appeal to young people are needed (218;252).

Exhibit 5.1. Respondent-observer issues in the dietary assessment of school age children and adolescents.^a

a. Adapted from Livingston and Robson, 2000 (161).