234
U N I T 2
Integrative Body Functions
Undernutrition and Eating
Disorders
Undernutrition continues to be a major health problem
throughout the world.
40
Protein-energy malnutrition
is most obvious in developing countries of the world,
where it is indirectly responsible for half of all deaths of
young children.
41
Even in developed nations, malnutri-
tion remains a problem.
Malnutrition and Starvation
Malnutrition and starvation are conditions in which a
person does not receive or is unable to use an adequate
amount of nutrients for body function. An adequate diet
should provide sufficient energy in the form of carbo-
hydrates, fats, and proteins; essential amino acids and
fatty acids for use as building blocks for synthesis of
structural and functional proteins and lipids; and the
necessary vitamins and minerals to function as coen-
zymes or hormones in vital metabolic processes or, as in
the case of calcium and phosphate, as important struc-
tural components of bone.
42
Among the many causes of malnutrition are poverty
and lack of knowledge about nutritional needs, acute
and chronic illness, and self-imposed dietary restric-
tions. Homeless people, the elderly, and the children
of the poor often demonstrate the effects of protein
and energy malnutrition, as well as vitamin and min-
eral deficiencies. Even the affluent may fail to recognize
that infants, adolescents, and pregnant women have
increased nutritional needs. Some types of malnutri-
tion are caused by acute and chronic illnesses, such as
malabsorption disorders. In contrast, clinical eating
disorders are caused by psychiatric illness.
Protein-Energy Malnutrition
Protein-energy malnutrition represents a depletion of
the body’s lean tissues caused by starvation or a com-
bination of starvation and catabolic stress. The lean tis-
sues are the fat-free, metabolically active tissues of the
body, namely the skeletal muscles, viscera, and cells of
the blood and immune system. Because lean tissues are
the largest body compartment, their rate of loss is the
main determinant of total body weight in most cases of
protein energy malnutrion.
Much of the literature on malnutrition and starva-
tion has dealt with infants and children in underdevel-
oped countries in which food deprivation results in an
inadequate intake of protein and calories to meet the
body’s energy needs. Protein-energy malnutrition in
this population commonly is divided into two distinct
conditions: marasmus (protein and calorie deficiency)
and kwashiorkor (protein deficiency). The pathologic
changes for both types of malnutrition include humoral
and cellular immunodeficiencies resulting from pro-
tein deficiency and lack of immune mediators. There
is impaired synthesis of pigments of the hair and skin
(e.g., hair color may change and the skin may become
hyperpigmented) due to a lack of substrate (tyrosine)
and coenzymes.
There are two functional compartments involved in
the distribution of proteins within the body: the
somatic
compartment
, represented by the skeletal muscles, and
the
visceral compartment
, represented by protein stores
in body organs, principally the liver.
42
These two com-
partments are regulated differently, with the somatic
compartment being affected more severely in marasmus
and the visceral compartment affected more severely in
kwashiorkor.
Marasmus
represents a progressive loss of muscle
mass and fat stores due to inadequate food intake
that is equally deficient in calories and protein.
42,43
It results in a reduction in body weight adjusted for
age and size. The child with marasmus has a wasted
appearance, with loss of muscle mass, stunted growth,
and loss of subcutaneous fat; a protuberant abdomen
(from muscular hypotonia); wrinkled skin; sparse,
dry, and dull hair; and depressed heart rate, blood
pressure, and body temperature. Diarrhea is common.
Since immune function is impaired, concurrent infec-
tions occur and place additional stress on an already
weakened body. An important characteristic of maras-
mus is growth failure; if sufficient food is not pro-
vided, these children will not reach their full potential
stature.
43
Kwashiorkor
results from a deficiency in protein in
diets that are relatively high in carbohydrates.
42,43
The
term
kwashiorkor
comes from an African word meaning
“the disease suffered by the displaced child,” because the
condition develops soon after a child is displaced from
the breast after the arrival of a new infant and placed on
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The risks associated with obesity include
hyperlipidemia, insulin resistance, and
hypertension, which together predispose to the
development of type 2 diabetes mellitus and
atherosclerotic cardiovascular disease (e.g.,
coronary artery disease, stroke). Obesity is also
associated with gallbladder disease, infertility,
osteoarthritis, sleep apnea, complications of
pregnancy, menstrual irregularities, nonalcoholic
fatty liver disease, thromboembolic disorders,
and poor wound healing.
■■
Childhood obesity is becoming an increasingly
prevalent nutritional disorder that predisposes
children and adolescents to hypertension,
dyslipidemia, type 2 diabetes mellitus, and
psychosocial stigma.
SUMMARY CONCEPTS
(continued)
