Adolescents

Contents

Nutritional Requirements Nutritional Problems

Nutritional Requirements

CHS Ruxton, Nutrition Communications, Cupar, UK J Fiore, University of Westminster, London, UK

© 2005 Elsevier Ltd. All rights reserved.

Introduction

Adolescence is the period of transition between childhood and adulthood. This reflects not only the physical and emotional changes experienced by the adolescent, but the development of dietary behaviors. Whereas younger children are characterized by their resistance to new experiences, the adolescent may use food to assert their independence, not always in a beneficial way. This section will cover development in adolescence and highlight nutrients that are important during this time. Information on adolescent energy and nutrient intakes from a broad range of countries will be presented. The findings will be put in context with dietary recommendations.

Physical Changes During Adolescence

Adolescence is generally assumed to be the period of human development from 10 to 18 years of age, a time during which rapid growth and physical maturity take place.

Growth

During prepubescent childhood, the growth of boys and girls follows a similar trajectory, although boys may be slightly taller and heavier than girls. Around the 9th year, the pubertal growth spurt, which can last up to 3.5 years, will occur in girls with boys beginning 2 years later. Girls reach their full height approximately 2 years before boys and are, therefore, the taller of the two sexes for a period of time. Current UK standards for height and weight during adolescence are presented in Table 1.

Maximum height velocity is generally seen in the year preceding menarche for girls and at around 14 years for boys. On average, weight velocity peaks at 12.9 years for girls and 14.3 years for boys. Annual growth rates during adolescence can be as much as 9 cm/8.8 kg in girls and 10.3 cm/9.8 kg in boys. Energy and protein intakes per kilogram body weight have been observed to peak during maximal growth, suggesting increased requirements during adolescence. Undernutrition in this crucial window of development can result in a slow height increment, lower peak bone mass, and delayed puberty. On the other hand, overnutrition is not without its risks. It is believed that obesity in young girls can bring about an early menarche, which then increases the risk of breast cancer in later adulthood. Menarche is deemed precocious if it occurs before the age of eight. Rising childhood obesity levels in Western countries have resulted in a rise in the proportion of girls displaying precocious menarche.

Table 1 Percentiles for height, weight, and body mass index

Age (years) Height (cm) Weight (kg) Body mass index

Table 1 Percentiles for height, weight, and body mass index

Age (years) Height (cm) Weight (kg) Body mass index

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