Chapter 14.doc

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10 Apr 2012
Chapter 14 – Adolescents
Adolescence is defined as the period of life between 11 and 21 yrs
Physical, emotional, and cognitive maturity is accomplished during adolescence
The dramatic physical growth and development experienced by adolescents significantly increases their needs for energy,
protein, vitamins, and minerals
Struggle for independence that characterizes adolescent psychosocial development often leads to the development of health-
compromising eating behaviors such as excessive dieting, meal skipping, use of unconventional nutritional and nonnutritional
supplements, and the adoption of fad diets
Normal Physical Growth and Development
Early adolescence encompasses the occurrence of puberty, the physical transformation of a child into a young adult
Biological changes that occur during puberty include sexual maturation, increases in height and weight, accumulation of skeletal
mass, and changes in body composition
oThe sequence of these events during puberty is consistent among adolescents but the age of onset, duration, and tempo
of these events vary a great deal between individuals
Sexual maturation (or biological age) should be used to assess biological growth and development and the individual nutritional
needs of adolescents rather than chronological age
Sexual Maturation Rating (SMR) *figure 14.1 on pg 358*, a.k.a. “Tanner Stages,” is a scale of secondary sexual characteristics
(physiological changes that signal puberty, including enlargement of the testes, penis, and breasts and the development of pubic
and facial hair) that allows health professionals to assess the degree of pubertal maturation among adolescents, regardless of
chronological age
oSMR is based on breast development and the appearance of pubic hair among females, and on testicular and penile
development and the appearance of pubic hair among males
oSMR stage 1 corresponds with prepubertal growth and development, while stages 2 through 5 denote the occurrence of
oAt SMR stage 5, sexual maturation has concluded
oSexual maturation correlates highly with linear growth, changes in weight and body composition, and hormonal changes
Menses is the process of menstruation
Among females the first signs of puberty are the development of breast buds and sparse, fine pubic hair occurring on average
between 8 to 13 years of age (SMR stage 2)
Menarche (the occurrence of the first menstrual cycle) occurs 2 to 4 years after the initial development of breast buds and pubic
hair, most commonly during SMR stage 4
Average age of menarche is 12.4 years, but menarche can occur as early as 9 or 10 yrs late or as late as 17 yrs old
Menarche may be delayed in highly competitive athletes or in girls who severely restrict their caloric intake to limit body fat
Enlargement of the testes (one of the 2 male reproductive glands located in the scrotum) and change in scrotal coloring are most
often the first signs of puberty among males, occurring between the ages of 10.5 and 14.5 years, with 11.6 yrs being the avg age
Development of pubic hair common during SMR stage 2
males show a great deal of variation in the chronological age at which sexual maturation takes place
On average, peak velocity of linear growth among males occurs during SMR stage 4
The peak velocity of linear growth occurs at 14.4 years of age, on average. At the peak of the growth spurt, adolescent males will
increase their height by 2.8 to 4.8 inches (7-12cm) a year
oLinear growth will continue throughout adolescence at a progressively slower rate, ceasing at about 21 yrs of age
Changes in Weight, Body Composition, and Skeletal Mass
As much as 50% of ideal adult body weight is gained during adolescence
Among females, peak weight gain follows the linear growth spurt by 3 to 6 months
oWeight gain slows around the time of menarche, but will continue into late adolescence
oPeak accumulation of muscle mass occurs around or just after the onset of menses
oBody composition changes dramatically among females during puberty
Among males, peak weight gain coincides with the timing of peak linear growth and peak muscle mass accumulation
oBody fat decreases in males during adolescence
A variety of factors contribute to accretion of bone mass including genetics, hormonal changes, weight-bearing exercise,
cigarette smoking, consumption of alcohol, and dietary intake of calcium, vitamin D, protein, phosphorus, boron, and iron.
Adequate intake of calcium, phosphorus, and protein is critical to support bone growth since bone is comprised largely of these
Early adolescence (11-14 yrs)
Begin to experience dramatic biological changes related to puberty
Development of body image and increased awareness of sexuality, peer influence is strong
Study found that situational factors such as where they ate and who they ate with were important factors in the food choices
female adolescents made
Females who mature early have been found to have more eating problems and poorer body image than their later-developing
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peers, they are also more likely to initiate “grown up” behaviors such as smoking, drinking alcohol, and engaging in sexual
activities at an earlier age
Cognitively, early adolescence is characterized by concrete thinking, egocentrism, and impulsive behavior, lack ability to see
how current behavior affects future health status
Middle Adolescence (15-17 yrs)
Marks development of emotional and social independence from family, especially parents
Conflicts over personal issues, including eating and physical activity behaviors, are heightened
Peer groups become more influential and their influence on food choices peaks
Physical growth and development are mostly completed during this stage
Initiation of and participation in health-compromising behaviors occurs
May believe they are invincible during this stage
Emergence of abstract reasoning skills occurs rapidly during mid ad. however these skills may not be applied to all areas of life,
adolescents will revert to concrete thinking skills if they feel overwhelmed or experience psychosocial stress
Begin to understand relationship between current health-related behaviors and future health even though their need to fit in may
supplant this understanding
Late adolescence (18-21 yrs)
Characterized by development of a personal identity and individual moral beliefs
Physical growth and development is largely concluded and body image issues less prevalent
Reduction in impulsive behaviors and peer pressure
Less economically and emotionally dependent on parents
Personal choice emerges
Future goals and interests, abstract thinking capabilities
Health and Eating-Related Behaviors during Adolescence
Conceptual model on pg 362 illustrates the many factors that influence eating behaviors of adolescents
Personal factors that influence eating behavior includes attitudes, beliefs, food preferences, self-efficacy (the ability to make
effective decisions and to take responsible action based on one’s own needs and desires), and biological changes
Environmental factors include the immediate social environment such as family, friends, and peer networks, and other factors
such as school, fast-food outlets, and social and cultural norms
Macrosystem factors, which include availability, food production and distribution systems, and mass media and advertising, play
a more distal and indirect role in determining food patterns, yet can exert a powerful influence on specific food choices
Adolescents of a lower socioeconomic status and from minority backgrounds have been found to be more likely to engage in less
healthy eating behaviors, and this often leads to higher prevalence of overweight
Eating habits of adolescents are not static; they fluctuate throughout adolescence in relation to psychosocial and cognitive
Data of adolescent females suggest that even though body-weight percentiles track throughout adolescence, little consistency
guides the intake of energy, nutrients, vitamins, and minerals from early to late adolescence
The average size of snacks adolescents consume has remained approximately the same, but the number of snacks consumed has
increased, accounting for the increased caloric intake
Adolescents are consuming a larger proportion of calories from snacking away from home, often at fast food restaurants
Soft drinks are the most commonly chosen snacks for females, and these account for about 6% of total caloric intake
Health practitioners working with adolescents need to understand that snacking is commonplace behavior among adolescents and
should work with them to improve food choices rather than discouraging snacking
Occurrence of meal skipping increases as adolescents mature
Breakfast is the most commonly skipped meal, as few as 21% of adolescents have been found to consume breakfast daily
oSkipping breakfast can dramatically decrease intakes of energy, protein, fiber, calcium and folate
Lunch is skipped by almost 25% and dinner is skipped by up to 8% of teens
Adolescents who skip meals should be counseled on convenient, portable, and healthy food choices that can be taken with them
and eaten as meals or snacks
Female adolescents eat almost 1/3 of their meals away from home, and the avg teen eats at a fast food restaurant twice a week
Vitamins and mineral intakes, including calcium, folate, fiber, iron, & vitamins A, C, E, B6 & B12, are higher among adolescents
who frequently consume family meals
oSimilar improvements in dietary intake are found among older adolescents living away from their parents who eat meals
with others compared to those who eat alone
A greater number of families that are eating together do so in front of the TV
Vegetarian Diets
Term vegetarian is used quite broadly and can consist of many different eating patterns
Semi- or partial-vegetarian: exclude red meat
Lacto-ovo-vegetarian: exclude meat, poultry, fish, seafood
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