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Trends in Teen Nutrition
Reprinted from Food Insight
January/February 1993
Brandy is worried about going to college next year."I know I'm going to gain weight, says the 17-year old high school cheerleader. "College is a very social time in your life, and eating is a social thing. I just know I'm going to come home gaining that 'freshman 10.'"
Heather, 17, disagrees. "I think I'll lose weight because I'll be able to monitor what I eat for breakfast, lunch and dinner. Not my mom." Katie, also 17, says she'll lose weight too. "I'll be too homesick in college to eat."
Brandy, Heather and Katie may not agree on how their diets will change when they move away from home next year, but there's no doubt they will be affected. Yet the three high-school seniors from Columbia, Md., admit their eating habits already have changed significantly during their teenage years. More responsibilities, like part-time jobs, and new freedoms, like dating and getting a driver's license, have affected personal decisions about when, where and what they eat.
"Adolescents have more autonomy than they ever had as children," said Jo Ann Hattner, RD, MPH, a clinical dietitian at Packard Children's Hospital at Stanford University. "Jobs and other after school activities often run into the dinner hours, so teenagers become more responsible for their daily good intake." In addition to extracurricular interests, changes in the traditional family also have affected teen nutrition. According to a study published in the May/June 1988 issue of the Journal of Nutrition Education, 73 percent of teenagers reported grocery shopping for their families; 83 percent said they shopped for food for themselves.
Single parent households or households where both parents work can result in absences of one or both parents during dinner. Thus food preparation is often left to teens and is largely determined by their own cooking savvy. But even if a balanced meal is served, parents know all too well there's no guarantee it will be eaten. Adolescents' food choices are often influenced by social pressures to achieve cultural ideals of thinness, demonstrate athletic prowess, gain peer acceptance, or assert independence from parental authority.
Hattner believes today's young adults are more interested in health and nutrition than ever before. But unlike their parents, teens seldom seek dietary advice to avoid illness. "Many teens are more concerned about body image and physical performance in sports rather than disease prevention," Hattner said. "They want to know, 'What can I do to build muscles?' or 'How can I lose weight?' Regardless of their motivation, the challenge is to teach them to apply sound, nutrition principles so they can safely reach their goal," she said.
Nutrient Needs
Teenagers need extra nutrients to support the adolescent growth spurt, which begins in girls at ages 10 or 11, reaches its peak at age 12 and is completed at about 15. In boys, it begins at 12 or 13 years of age, peaks at 14 and ends at about 19.This intensive growth period brings dramatic increases in height as well as hormonal changes affecting every body organ, including the brain. Iron is especially important with the onset of menstruation in girls and the increase in lean body mass in boys. The recommended daily allowance for iron is 12 to 15 milligrams (mg) a day.
The increase in skeletal mass also boosts teens' requirements for calcium to about 1,200 mg a day. Approximately half of adult bone structure is deposited during adolescence. Calcium is important even for young adults who have complete their linear growth spurt, since the mineral continues to be deposited in their bones for another decade.
Teens' caloric needs vary depending on their growth rate, degree of physical maturation or body composition, and activity level. Males generally have higher energy requirements than females due to their larger proportion of lean body mass to adipose tissue. But individual growth spurts also must be considered. For example, a rapidly-growing athletic 15-year old boy may need 4,000 calories a day just to maintain his weight. However, an inactive girl the same age, whose growth is nearly completed, may need fewer than 2,000 calories to avoid weight gain.
What Teens Eat
How do the diets of today's teens measure up in terms of health recommendations?Various studies have been conducted to determine how well adolescents comply with the U.S. Dietary Guidelines. Describing patterns of food intake are important, since it is the total diet, not single foods, that determine the nutritional quality of intake. Patricia West, M.S., and Evelyn Farrior, Ph.D., R.D., surveyed 521 North Carolina males and females, 15 to 16 years old, on the number of servings consumed form 35 different food categories within the previous 24 hours. The results, published in the Spring 1991 issue of the School Food Service Research Review, showed the teens consumed too few servings of food groups supplying iron, calcium, vitamin A and beta-carotene to ensure adequate intake of these nutrients. Many students did not eat fruits and vegetables.
Other studies measuring quantitative food intake, including the 1977-78 National Health and Nutrition Examination Survey II, estimate adolescents consume about 38 percent of their total calories from fat, 15 percent of their calories from saturated fat and over 300 mg of cholesterol per day. I contrast, most U.S. health authorities recommend anyone over the age of two consume 30 percent of calories from fat, 10 percent of calories from saturated fat and up to 300 mg of cholesterol each day.
According to the National Research Council, major sources of fat in the American diet are from meat and dairy products. Thus achieving such goals for fat and cholesterol, while maintaining adequate intakes of iron and calcium, can seem challenging. But drastic dietary changes may not be needed, says Robyn Flipse, R.D., a consulting dietitian in New Jersey. Rather than eliminating dairy products or red meat and other iron-rich animal foods, Flipse recommends eating smaller servings and low-fat or leaner versions of such foods.
Flipse and other nutritionists also are reporting an increase in the number of teens they counsel who have become vegetarians. In addition to iron and calcium, such diets are at risk of being deficient in protein, calcium and zinc. Thus, it's important that both vegetarian teens and their parents seek dietary advice from a registered dietitian.
Weight Management
Overweight is one of the most serious nutrition problems of adolescents, particularly among Native Americans, Hispanics and low-income African Americans.Although the health risks have been well documented in adults, there has been no clear evidence overweight in youth is detrimental later in life. But a study released last fall by Aviva Must, Ph.D., of the U.S. Department of Agriculture's Human Nutrition Research Center in Boston, shows being overweight as a teenager is associated with serious health problems later in life, regardless of whether the teen becomes overweight as an adult. The study, reported in the New England Journal of Medicine, was based on 508 adults who participated in the Harvard Growth Study some 55 years ago.
Overweight teenage boys were twice as likely as thin adolescents to die by age 70, primarily from heart disease. They also were about five times more likely to develop colon cancer and twice as likely to develop gout than their lean counterparts. Overweight girls were 60 percent more likely to have arthritis and twice as likely to suffer heart disease in their 70s than girls who were not overweight.
Must said the findings underscore the importance of preventing overweight in youth by monitoring diet as well as exercise.
Eating Disorders
At the other end of the spectrum are teens who are undernourished due to eating disorders. Although their current weight is normal, many adolescents feel pressured to be "ideally" thin like models in movies or magazines. Some girls embark on their first diet before even leaving elementary school.According to the National Center for Health Statistics (NCHS), one in 100 females between the ages of 12 and 18 has anorexia nervosa, an eating disorder that causes people to severely limit their food intake. Those with bulimia indulge in bingeing and purging by vomiting or using laxatives. Although more common in females, about 5 to 10 percent of all eating disorders occur in males.
Anorexia and bulimia can have serious consequences such as convulsions, renal failure, irregular heartbeats and dental erosion. In adolescent girls, anorexia can delay the onset of menstruation, permanently minimize stature and result in osteoporosis.
New guidelines for adolescent preventive services issued by the American Medical Association in December 1992, recommend all adolescents receive annual health guidance on ways to achieve a healthy diet and safe weight management, as well as the benefits of regular exercise.
The guidelines also recommend screening for selected adolescents to determine their risk of developing hyperlipidemia and coronary heart disease.
In sum, physical, social and emotional changes experienced during adolescence can profoundly impact teens' nutritional status and eating patterns. Although such young adults are rarely motivated to learn about nutrition for longevity sake, teaching them how to apply sound dietary principles to reach their goals can help build the foundation to a healthier life.
Tips for Teens
Snacking is a well-established eating pattern among adolescents.Although snacks can be a source of needed nutrients and calories, it's important that they don't become a substitute for regular meals. Selections should be balanced with other food choices over the entire day. If snacking leads to unwanted pounds, these simple weight management tips can guide the way to Change:
- Count out crash diets or quick weight-loss schemes.
- Have patience in losing a half pound to a pound per week.
- Always drink plenty of water or other fluids.
- Never skip meals in efforts to lose weight.
- Get up and go, increase your physical activity.
- Eat a variety of foods.
Reprinted from the International Food Information Council Foundation, 1993
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