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Growth and Nutrition


An individual’s weight and body composition (proportion of fat and fat distribution) offer information about health status and may provide a clue to the presence of disease when out of balance. Nutrition is considered the science of food as it relates to promoting optimal health and preventing chronic disease. Nutritional intake and status offer insight into an individual’s health status. A nutritional assessment is an analysis of an individual’s approximate nutrient intake and relates it to the history, physical examination findings, body size measurements, and biochemical measures. This chapter focuses on the assessment of an individual’s body size and nutritional status and the examination for growth, gestational age, and pubertal development.

Physical Examination Components

Nutritional Assessment

From the history and physical examination, assess the patient’s nutritional status, including:

  • Recent growth, weight loss, or weight gain

  • Chronic illnesses affecting nutritional status or intake

  • Medication and supplement use

  • Assessment of nutrient intake

Growth Assessment

Obtain the following body size measurements and compare them to standardized tables:

  • Standing height

  • Weight

  • BMI

  • Waist circumference

  • Calculate waist-height ratio

Anatomy and Physiology

In this chapter, the terms “female” and “male” are used in order to differentiate between the body composition, physical and sexual development, and growth measurements in patients assigned as female or male at birth, respectively. This becomes important to the examination and health assessment of patients who are transgender male, transgender female, and non-binary.

Food nourishes the body by supplying necessary nutrients and calories to function in one or all of three ways:

  • To provide energy for necessary activities

  • To build and maintain body tissues

  • To regulate body processes

The nutrients necessary to the body are classified as macronutrients (carbohydrates, protein, and fat), micronutrients (vitamins, minerals, and electrolytes), and water. Energy requirements are based on the balance of energy expenditure associated with body size, composition, and the level of physical activity. An appropriate balance contributes to long-term health and allows for the maintenance of optimal physical activity. Adequate nutrition, from a well-balanced diet, supports growth, the increase in size of an individual, or of a single organ. Growth is also dependent on a sequence of endocrine, genetic, environmental, and nutritional influences.

Many hormones must interact and be in balance for normal growth and development to proceed ( Fig. 8.1 ). Two hypothalamic hormones control growth hormone synthesis and secretion in the anterior pituitary gland. Growth hormone–releasing hormone (GHRH) stimulates the pituitary to release growth hormone. Somatostatin, or growth hormone–inhibiting hormone (GHIBH), inhibits the secretion of both GHRH and thyroid-stimulating hormone (TSH). Growth hormone is secreted in pulses, with 70% of secretion occurring during deep sleep ( Sam and Frohman, 2008 ). Growth hormone promotes growth and increases in organ size, and it regulates carbohydrate, protein, and lipid metabolism.

FIG. 8.1, Growth hormone (GH) directly accelerates the rate of protein synthesis in skeletal muscle and bones.

Thyroid hormone stimulates growth hormone secretion and the production of insulin-like growth factor 1 (IGF-1) and interleukins 6 and 8 (IL-6 and IL-8), which have important roles in bone formation and resorption. The thyroid hormone also affects the growth and maturation of other body tissues.

IGF-1 is a growth hormone produced by the liver and in peripheral tissues, like bone. Through activation of IGF-1 receptors throughout the body, IGF-1 exerts a negative feedback effect on growth hormone secretion and mediates the effect of growth hormone on bone, muscle, nervous system, and immune system cells (Werner et al., 2008). Ghrelin, a peptide, known as the “hunger hor mone,” helps control growth hormone release and influences food intake and obesity development ( Sakata and Sakai, 2010 ).

Leptin has a key role in regulating body fat mass, and its concentration is thought to be a trigger for puberty by informing the central nervous system that adequate nutritional status and body fat mass are present to support pubertal changes and growth ( Low, 2011 ). Before puberty, body composition does not differ much between males and females. During puberty, with an increase in leptin, a relative decrease in fat percentage develops in males and an increase occurs in females ( Rogol, 2010 ). During puberty, the gonads begin to secrete testosterone and estrogen. Rising levels of these hormones trigger the release of gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) from the hypothalamus that stimulates the gonads to release more sex hormones. The genitalia begin growing to adult proportions. Testosterone enhances muscular development and sexual maturation and promotes bone maturation and epiphyseal closure. Estrogen stimulates the development of female secondary sexual characteristics, regulating the timing of the growth spurt and the acceleration of skeletal maturation and epiphyseal fusion. Androgens, secreted by the adrenal glands, promote masculinization manifested by secondary sex characteristics and skeletal maturation.

Growth at puberty is dependent on the interaction of growth hormone, IGF-1, leptin, and sex steroids (androgens). The sex steroids stimulate an increased secretion of growth hormone, which in turn mediates the dramatic increase in IGF-1. This leads to the adolescent growth spurt.

Differences in Growth by Organ System

Each organ or organ system has its particular period of rapid growth marked by rapid cell differentiation. Each individual has a unique growth timetable and final growth outcome, but the sequential growth patterns are consistent. An external environmental or abnormal pathophysiologic process may intervene and influence the expected growth pattern ( Fig. 8.2 ).

FIG. 8.2, Growth rates for the body as a whole and three types of tissues.

The growth of the musculoskeletal system and most organs such as the liver and kidneys follows the growth curves described for stature. Skeletal growth is considered complete when the epiphyses of long bones have completely fused during late puberty. More than 90% of the skeletal mass is present by 18 years of age ( Reiter and Rosenfield, 2008 ).

Weight is closely related to growth in stature and organ development. Growth and development are influenced by nutritional adequacy, which contributes to the number and size of adipose cells. The number of adipose cells increases throughout childhood. Gender-related differences in fat deposition appear in infancy and continue through adolescence.

Lymphatic tissues (i.e., lymph nodes, spleen, tonsils, adenoids, and blood lymphocytes) are small in relation to total body size but are well developed at birth. These tissues grow rapidly to reach adult size by 6 years of age. By age 10 to 12 years, the lymphatic tissues are at their peak, about double adult size. During adolescence, they decrease to adult size.

The internal and external reproductive organs grow slowly before puberty. The reproductive organs double in size during adolescence, achieving maturation and function.

The brain, along with the skull, eyes, and ears, completes physical development more quickly than any other body part. The most rapid and critical period of brain growth occurs between conception and 3 years of age. By 34 weeks’ gestation, 65% of the weight of a newborn’s brain is present. Gray matter and myelinated white matter increase dramatically between the 34th and 40th weeks of gestation. At the time of full-term birth, the brain’s structure is complete and an estimated 1 billion neurons are present. Glial cells, dendrites, and myelin continue to develop after birth, and by 3 years of age, most brain growth is completed ( Fiegelman, 2011 ). The head circumference increases in infants and toddlers as brain growth occurs. During adolescence, the size of the head further increases because of the development of air sinuses and the thickening of the scalp and skull.

Infants and Children

As infants and children grow, the change in body proportion is related to the pattern of skeletal growth ( Fig. 8.3 ).

FIG. 8.3, Changes in body proportions from 8 weeks of gestation through adulthood.

Growth of the head predominates during the fetal period. Fetal weight gain follows growth in length, but weight reaches its peak during the third trimester with the increase in organ size. An infant’s birth weight is influenced by genetic predisposition, gestational age, the mother’s prepregnancy weight, weight gain during pregnancy, environmental exposures like secondhand smoke, overall maternal health, and intercurrent disease or complications in pregnancy such as gestational diabetes.

During infancy, the growth of the trunk predominates. Weight gain is initially rapid, but the speed with which weight is gained decreases over the first year of life. The fat content of the body increases slowly during early fetal development and then increases during infancy.

The legs are the fastest-growing body part during childhood, and weight is gained at a steady rate. Fat tissue increases slowly until 7 years of age, at which time a prepubertal fat spurt occurs before the true growth spurt.

The trunk and the legs lengthen during adolescence and lean body mass averages 80% in males and females ( Cromer, 2011 ). During adolescence, about 50% of the individual’s ideal weight is gained, and the skeletal mass and organ systems double in size.

During adolescence, males develop broader shoulders and greater musculature; females develop a wider pelvic outlet. Males have a slight increase in body fat during early adolescence and then have an average gain in lean body mass to 90%. Females accumulate subcutaneous fat and have a slight decrease in lean body mass to an average of 75% ( Cromer, 2011 ).

Pregnant Patients

Progressive weight gain is expected during pregnancy, but the amount varies among patients. The growing fetus accounts for 6 to 8 pounds of the total weight gained. The remainder results from an increase in maternal tissues:

  • Fluid volume—2 to 3 pounds

  • Blood volume—3 to 4 pounds

  • Breast enlargement—1 to 2 pounds

  • Uterine enlargement—2 pounds

  • Amniotic fluid—2 pounds

  • Maternal fat and protein stores—4 to 6 pounds

The rate of desirable weight gain follows a curve through the trimesters of pregnancy, slowly during the first trimester and more rapidly during the second and third trimesters. Maternal tissue growth accounts for most of the weight gained in the first and second trimesters. Fetal growth accounts for most weight gained during the third trimester.

Maternal nutrition before and during pregnancy and during lactation may have subtle effects on the developing brain of the infant and on the outcome of the pregnancy. Patients who have inadequate weight gain are at greater risk for delivering a low-birth-weight infant. Epigenetic research is revealing the potential consequences of inadequate maternal nutrition on the adult health of the fetus ( Box 8.1 ).

BOX 8.1
Epigenetic Research and Nutrition
From Cota and Allen (2010) .

Epigenetic research is revealing an association between an individual’s genome and environmental exposures during fetal life and adult health. Undernutrition during the second and third trimesters of pregnancy is believed to influence the fetus during the critical growth stages. Undernutrition (poor maternal nutrition or poor intrauterine environment) stresses the fetus, leading to adaptive and permanent changes in the infant’s endocrine and metabolic processes. Restricted fetal growth and a low birth weight for gestational age are associated with increased adult cardiovascular risk factors such as hypertension, insulin resistance, and abnormal lipid metabolism. These risk factors are further influenced by nutrition and growth after birth. Increased nutrition can lead to compensatory growth in these higher-risk infants during the first 2 years of life, resulting in a child who has an increased body mass index and body fat by 5 years of age.

Postpartum weight loss often occurs over the first 6 months after birth, with most weight loss occurring by 3 months after delivery. Patients who gained more than the recommended weight during pregnancy are less likely to return to their prepregnancy weight. They may be susceptible to future obesity and its health consequences.

Older Adults

Physical stature declines in older adults beginning at approximately 50 years of age. The intervertebral disks thin and kyphosis develops with the potential of osteoporotic vertebral compression.

Individuals older than 60 years often have a decrease in weight for height and BMI and a loss of 5% body weight over several years. An increase in body fat also occurs as skeletal muscle declines and anabolic steroid secretion is reduced. Older adults also frequently have decreased physical activity, which contributes to skeletal muscle loss with an associated increased risk for poor function and disability (Kalyani et al., 2014). Physical activity recommendations vary by age. See Table 8.1 for guidelines for physical activity by age group from the U.S. Department of Health and Human Services (HHS).

TABLE 8.1
Physical Activity Guidelines for Americans Recommendations
Adapted from U.S. Department of Health and Human Services. Physical activity guidelines for Americans, 2nd edition. Washington, DC: U.S. Department of Health and Human Services; 2018.
Age Recommendations
3–5 years Preschool-aged children should be physically active throughout the day (ideally 3 hours per day of active play and structured activities).
6–17 years Children and adolescents should do 60 minutes or more of physical activity daily.

  • Aerobic (e.g., running, swimming, dancing, bicycling): Most of the 60 or more minutes a day should be either moderate- a or vigorous-intensity b aerobic physical activity and should include vigorous-intensity physical activity at least 3 days a week.

  • Muscle strengthening: c As part of their 60 or more minutes of daily physical activity, children and adolescents should include muscle-strengthening physical activity on at least 3 days of the week.

  • Bone strengthening: d As part of their 60 or more minutes of daily physical activity, children and adolescents should include bone-strengthening physical activity on at least 3 days of the week.

  • It is important to encourage young people to participate in physical activities that are appropriate for their age, are enjoyable, and offer variety.

18–64 years

  • All adults should move more and sit less throughout the day. Some physical activity is better than none, and adults who participate in any amount of physical activity gain some health benefits.

  • For substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) a week of moderate-intensity or 75 minutes (1 hour and 15 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Aerobic activity should be performed in episodes of at least 10 minutes, preferably spread throughout the week.

  • For additional and more extensive health benefits, adults should increase their aerobic physical activity to 300 minutes (5 hours) a week of moderate-intensity activity.

  • Adults should also include muscle-strengthening activities that involve all major muscle groups on 2 or more days a week.

65 years and older

  • Older adults should follow the adult guidelines. When older adults cannot meet the adult guidelines, they should be as physically active as their abilities and conditions will allow.

  • Older adults should do exercises that maintain or improve balance as well as aerobic and muscle-strengthening activities.

  • Older adults should determine their level of effort for physical activity relative to their level of fitness.

  • Older adults with chronic conditions should understand whether and how their conditions affect their ability to do regular physical activity safely.

a Moderate-intensity physical activity: Aerobic activity that increases a person’s heart rate and breathing to some extent. On a scale relative to a person’s capacity, moderate-intensity activity is usually a 5 or 6 on a 0 to 10 scale. Brisk walking, dancing, swimming, or bicycling on a level terrain are examples.

b Vigorous-intensity physical activity: Aerobic activity that greatly increases a person’s heart rate and breathing. On a scale relative to a person’s capacity, vigorous-intensity activity is usually a 7 or 8 on a 0 to 10 scale. Jogging, singles tennis, swimming continuous laps, or bicycling uphill are examples.

c Muscle-strengthening activity: Physical activity, including exercise that increases skeletal muscle strength, power, endurance, and mass. It includes strength training, resistance training, and muscular strength and endurance exercises.

d Bone-strengthening activity: Physical activity that produces an impact or tension force on bones, which promotes bone growth and strength. Running, jumping rope, and lifting weights are examples.

Along with a decline in physical activity, an increase in overweight and obese older adults has been documented over the past 15 to 20 years. An age-associated reduction in size and weight of various organs has been identified, especially of the liver, lungs, and kidneys (McCance et al., 2015).

Review of Related History

For each of the symptoms or conditions discussed in this section, topics to include in the history of the present illness are listed. Responses to questions about these topics provide clues for focusing the physical examination and developing an appropriate diagnostic evaluation. Questions regarding medication use (prescription and over-the-counter preparations) as well as complementary and alternative therapies are relevant for each area.

History of Present Illness

Weight Loss

  • Compared with usual weight; time period (sudden, gradual); intentional or unintentional

  • Desired weight loss: eating pattern, diet plan used, food preparation, food group avoidance, average daily calorie intake, appetite, exercise pattern, support group participation, weight goal

  • Undesired weight loss: anorexia; vomiting or diarrhea, difficulty swallowing, other illness symptoms, time period; frequent urination, excessive thirst; change in lifestyle, activity, mood, and stress level

  • Preoccupation with body weight or body shape: never feeling thin enough, fasting, unusually strict caloric intake; unusual food restrictions or cravings; laxative abuse, induced vomiting; amenorrhea; excessive exercise; mood, stress level; alcohol intake

  • Medications: chemotherapy, diuretics, insulin, fluoxetine, prescription and nonprescription appetite suppressants, laxatives, oral hypoglycemics, steroids, herbal supplements

Weight Gain

  • Total weight gained: time period, sudden or gradual, desired or undesired, possibility of pregnancy

  • Change in lifestyle: change in social aspects of eating; more meals eaten out of the home; meals eaten quickly and “on the go”; change in meal preparation patterns; change in exercise patterns, mood, stress level, or alcohol intake

  • Medications: steroids, oral contraceptives, antidepressants, insulin

Changes in Body Proportions

  • Coarsening of facial features, enlargement of hands and feet, moon facies

  • Change in fat distribution: trunk versus generalized

Increased Metabolic Requirements

  • Infancy, prematurity, congenital heart disease

  • Fever, infection, burns, trauma, pregnancy, hyperthyroidism, cancer, athlete

  • External losses (e.g., fistulas, wounds, abscesses, chronic blood loss, chronic dialysis)

Past Medical History

  • Chronic illness: liver disease, celiac disease, inflammatory bowel disease, surgical resection of the gastrointestinal tract, diabetes, congestive heart failure, hypothyroidism, hyperthyroidism, pancreatic insufficiency, chronic infection (e.g., human immunodeficiency virus [HIV] and tuberculosis), or allergies

  • Previous weight loss or gain efforts: maximum body weight, minimum weight as an adult

  • Previously diagnosed eating disorder, hypoglycemia

Family History

  • Obesity, dyslipidemia ( Box 8.2 )

    BOX 8.2
    Statistics on Obesity and Diet-Related Chronic Diseases in the United States
    From the Centers for Disease Control and Prevention ( www.cdc.gov/obesity/index.html ) and the 2015-2020 Dietary guidelines for Americans.

    In the United States just over one-third of adults older than 20 years are obese and an additional one-third are overweight. Poor diet and physical inactivity (regardless of weight status) are associated with serious chronic diseases including type 2 diabetes, hypertension, cardiovascular disease, osteoporosis, and some types of cancer.

    • About half of American adults (117 million individuals) have one or more preventable chronic diseases related to poor diet and physical inactivity.

    • More than 29 million U.S. adults (9.3% of the U.S. population) have diabetes. Over 90% of these individuals have type 2 diabetes. An additional 86 million adults have prediabetes.

    • Cardiovascular disease (coronary heart disease, stroke, hypertension, and high total blood cholesterol) affected 35% of the U.S. population in 2010. About 610,000 Americans die from heart disease each year; 73.5 million adults have high low-density lipoprotein (LDL). About 75 million adults have hypertension and an additional third have prehypertension.

    • Cancers linked to poor diet include breast (postmenopausal), endometrial, colon, kidney, gallbladder, and liver.

    • The Division of Nutrition, Physical Activity, and Obesity at the Centers for Disease Control and Prevention has a wealth of information and useful resources for patients and healthcare professionals ( www.cdc.gov/nccdphp/dnpao/index.html ).

  • Constitutionally short or tall stature, precocious or delayed puberty

  • Genetic or metabolic disorder: diabetes (see list of chronic illnesses under Past Medical History)

  • Eating disorder: anorexia, bulimia

  • Alcohol use disorder

Personal and Social History

  • Nutrition: appetite; usual calorie intake; vegetarianism; medical nutrition therapy guidelines followed; religious/cultural food practices; proportion of fat, protein, carbohydrate in the diet; intake of major vitamins and minerals (e.g., vitamins A, C, and D; iron; calcium; folate)

  • Use of vitamin, mineral, and herbal supplements

  • Usual weight and height; current weight and height; ability to maintain weight, goal weight

  • Use of alcohol

  • Use of illicit drugs

  • Food insecurity (i.e., limited or uncertain availability of nutritionally adequate and safe foods); limited/fixed income; eligibility for the Supplemental Nutrition Assistance Program (SNAP; formerly the Food Stamp Program); financial and psychosocial stressors

  • Functional assessment (i.e., ability to shop and prepare foods); access to healthy foods in their neighborhood; access to food storage/preparation equipment (refrigerator, stove, oven)

  • Typical mealtime situations, companions, living environment

  • Use of oral supplements, tube feedings, parenteral nutrition

  • Dentition: dentures, missing teeth, gum disease

Infants

  • Estimated gestational age, birth weight, length, head circumference

  • Following an established percentile growth curve

  • Unexplained changes in length, weight, or head circumference

  • Poor growth/failure to thrive: falling one or more standard deviations off growth curve pattern; below the fifth percentile for weight and height; infant small for gestational age; quality of parent-infant bond and interaction; psychosocial stressors and food insecurity

  • Rapid weight gain: overfeeding

  • Nutrition: breastfeeding frequency and duration; type and amount of infant formula; method of formula preparation; time it takes to drink one feeding; intake of protein, calories, vitamins, and minerals adequate for growth; vegetarianism; cow’s milk protein and other food allergies; vitamin and mineral supplements; number of fast food meals eaten per week; eligibility for Women, Infants, and Children (WIC) program or school breakfast and lunch programs

  • Hours of screen time per day (i.e., television, computer use, video and electronic games); access to safe areas for physical activity

  • Chronic illness: cystic fibrosis, phenylketonuria (PKU), celiac disease, inborn errors of carbohydrate metabolism, amino acid and fatty acid oxidation disorders, tyrosinemia, homocystinuria, Prader-Willi syndrome

  • Development: achieving milestones at appropriate ages

  • Congenital anomalies, prematurity, prolonged neonatal hospitalization, cleft palate, malformed palate, tongue thrust, feeding and swallowing disorders, prolonged enteral tube feeding (gastrostomy and gastrojejunostomy), gastroesophageal reflux, malabsorption syndrome or chronic diarrhea, formula intolerance, neurologic disorders, congenital heart disease, others

Adolescents

  • Initiation of sexual maturation of females: early (before 7 years) or delayed (beyond 13 years); signs of breast development and pubic hair, age at menarche

  • Initiation of sexual maturation of males: early (before 9 years) or delayed (beyond 14 years); signs of genital development and pubic hair

  • Short stature: not growing as fast as peers, change in shoe and clothing size in the past year, extremities short or long for the size of the trunk, height of parents, size of head disproportionate to the body

  • Tall stature: height of parents, growing faster than peers, signs of early sexual maturation

  • Nutrition: intake of protein, calories, vitamins, and minerals adequate for growth; vegetarianism; number of fast food meals eaten per week; food allergies; vitamin and mineral supplements; herbal supplements; appetite suppressants; laxative use; alcohol use

  • Preoccupation with weight; overly concerned with developing muscle mass, losing body fat; excessive exercise; weighs self daily, boasts about weight loss, weight goals; omits perceived fattening foods and food groups from the diet

  • Risk factors for eating disorders

    • Weight preoccupation

    • Poor self-esteem, perfectionist personality

    • Self-image perceptual disturbances

    • Chronic medical illness (insulin-dependent diabetes)

    • Family history of eating disorders, obesity, alcohol use disorder, or affective disorders

    • Cultural pressure for thinness or outstanding performance

    • Athlete driven to excel (e.g., gymnasts, ice-skaters, dancers, boxers, and wrestlers)

    • Food cravings, restrictions

    • Compulsive/binge eating

    • Difficulties with communication and conflict resolution; separation from family

    • Use of appetite suppressants and/or laxatives

  • Chronic disease, such as inflammatory bowel disease, cystic fibrosis, malignancy

  • Medications: steroids, growth hormones, anabolic steroids

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