LIFESTYLE CHOICES
INFLUENCE OBESITY AND
THE METABOLIC SYNDROME
IN CHILDREN
by L. Jerome Brandon, Ph.D., FACSM and Larry Proctor, Ph.D.
Learning objective
• To gain a better understanding of what constitutes the metabolic
syndrome in children, the interrelationships among the conditions
of the metabolic syndrome, and how the metabolic syndrome can
be effectively managed in children.
Key words:
Balanced Diets, Insulin Resistance Syndrome, Physical Activity,
Sedentary, Health
L
ifestyle choices in the 21st century are
frequently centered on individual and
family activities of expediency, rather
than sound diets and wellness, and have
resulted in an obesogenic (environmental conditions that encourage excess weight gain) and
chronic disease culture that is responsible for
the deteriorating health in today’s children. An
example of a chronic disease observed in today’s
children related to this culture is the metabolic
syndrome. To assess the interactive relationships
for the risk factors of the metabolic syndrome,
we have developed a theoretical model (Figure 1)
of how these factors influence each other and
contribute to cardiovascular disease. The model
indicates that glucose intolerance/insulin resistance and obesity are two risk factors that contribute directly and indirectly, through their
relationship with the other three risk factors,
to cardiovascular disease. The other risk factors
contribute directly to cardiovascular disease. To
better understand these relationships, the focus
of this article will be to define the metabolic
syndrome in children; discuss the impact of and
VOL. 12/ NO. 4
the difficulty assessing childhood obesity; the
relationships among obesity, lipoproteins, and
glucose; the relationships among blood pressure
and other metabolic syndrome risk factors; and
procedures that help in managing the metabolic
syndrome.
DEFINITION OF THE METABOLIC
SYNDROME IN CHILDREN
The metabolic syndrome is the clustering of
metabolic risk factors and has gone by several
different names over the years: syndrome X,
insulin resistance syndrome, prediabetes, metabolic syndrome, dysmetabolic syndrome,
plurimetabolic syndrome, cardiometabolic syndrome, dyslipidemic hypertension, and hypertriglyceridemic waist (1). It was initially called
insulin resistance (type 2 diabetes) syndrome
because it developed from insulin resistance
that resulted in compensatory excess insulin in
the blood that was frequently triggered by
obesity (2). Because type 2 diabetes was once
thought of as adulthood onset of diabetes, the
metabolic syndrome in children has only
recently been identified, and there still is no
universally accepted definition for children (3).
Defining the metabolic syndrome in children
is difficult because of constant body changes
associated with maturation. The definition developed by Sarah de Ferranti, M.D., M.P.H., and
colleagues in the Department of Cardiology at the
Children’s Hospital in Boston, Massachusetts,
will be the reference for pediatric metabolic
syndrome discussions in this article. They define
pediatric metabolic syndrome as the clustering of
three or more of the following conditions in a
child: fasting triglycerides greater than or equal to
100 mg/dL, high-density lipoprotein cholesterol
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Obesity and the Metabolic Syndrome in Children
(HDL-C) less than or equal to 50 mg/dL, fasting glucose greater
than or equal to 110 mg/dL, waist circumference greater than the
75th percentile for age and sex, and systolic blood pressure
greater than the 90th percentile for sex, age, and height. The
definition takes into consideration maturation and was designed
for adolescents, but has use for younger children (4).
IMPACT OF AND DIFFICULTY OF ASSESSING OBESITY
The obesogenic culture that causes obesity not only affects the
physical health of children, it also impacts them socially,
educationally, and financially. Juhee Kim, Sc.D. (5), at the
Harvard University School of Public Health concludes that
independent of baseline socioeconomic status and performance
on aptitude tests, overweight and obese adolescents are less
likely to marry, complete fewer years of school, and are more
likely to be poor as adults. Lifestyle choices that include
chronic patterns of poor diets and physical inactivity will cause
major health problems and may have the greatest overall impact
on the quality of life in the United States during the next three
or four decades (5).
According to data from the National Health and Nutrition
Examination Survey III (6), in the last few decades, childhood
obesity has tripled to a prevalence of greater than 15% (5). Obesity can be viewed as a root disease (one from which a number of
others develop) because health problems presently associated with
obesity were essentially nonexistent 15 to 20 years ago.
Because of poor lifestyle choices such as decreased
physical activity, consuming large quantities of fast foods that
often are fried and lacking in nutritional content, and sedentary
entertainment, such as television viewing and playing video
games, many children today are developing the preculture for
type 2 diabetes as young as 6 or 7 years (7). This trend has a
negative impact on childhood wellness and will grow larger if
not addressed with proactive healthy lifestyle choices.
Overweight and obesity increased 120% in African American
and Hispanic children, and 50% in white children from 1986 to
Figure 1. Theoretical model of relationships among metabolic syndrome risk
factors in children.
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1998. Overweight and obesity have continued to increase;
currently, one in seven children and adolescents in the United
States is overweight or obese (8,9). Estimates of overweight and
obesity in children are not based on body fat measurements, but
typically are based on body mass index (BMI), which is the
amount of weight per unit of height. The overweight classification for children is a BMI greater than or equal to the 85th
percentile to less than or equal to 95th percentile for age and sex,
and obesity is a BMI greater than the 95th percentile for age and
sex. Caution should be used when determining the clustering
of overweight and obesity measured by BMI with other metabolic conditions, and this is especially true when children of
different racial backgrounds are evaluated. For example, African
American children have more dense skeletons and may have a
different lean body tissue composition for a given unit of height
than white children matched by age and sex. A BMI at the 85th
percentile for an African American child may provide different
clustering relationships with other metabolic syndrome conditions than for a white child (10,11).
RELATIONSHIPS OF OBESITY WITH
LIPOPROTEINS AND GLUCOSE
When children are evaluated for metabolic syndrome based on
BMI classifications, a higher coronary heart disease risk profile
is observed for total cholesterol (TC), HDL-C, and low-density
lipoprotein cholesterol (LDL-C) in boys with BMI values
greater than the 95th percentile. For the girls, only triglycerides
are higher for those with the higher BMI values. These data
clearly indicate that the relationships of BMI with blood
lipoproteins and lipids for boys are different from girls. Greater
clustering of blood lipoproteins and lipids with BMI seems to
occur in the boys (12).
Dr. Ribeiro and colleagues (12) at the University of Porto,
Portugal, report that most children (62% of boys and girls) at
risk for obesity are more likely to experience other metabolic
syndrome risk factors. Work in other laboratories supports this
finding because overweight and obesity are reported to be
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VOL. 12/ NO. 4
associated with type 2 diabetes, hypertension, lipid abnormalities, and pulmonary obstructive diseases (8).
In a metabolic study, an obese group and a control group of
children aged 6 to 14 years underwent an oral glucose tolerance
test and were measured for plasma glucose, insulin levels,
insulin sensitivity, and insulin resistance as evaluated by mathematical modeling. Obese children were found to have significantly higher blood pressure (systolic and diastolic), triglycerides,
TC, LDL-C, and lower HDL-C (good cholesterol) than normalweight children. Plasma glucose levels during the oral glucose
tolerance test were similar in both obese and control children,
whereas plasma insulin levels were significantly higher in obese
children. Insulin sensitivity and glucose utilization rates were
lower in the obese. In summary, obesity impacts many of the
other metabolic syndrome risk factors in children (12).
RELATIONSHIP BETWEEN BLOOD PRESSURE AND
OTHER METABOLIC SYNDROME CONDITIONS
Metabolic syndrome risk factors all contribute to cardiovascular
disease but seem to make direct and/or indirect contributions
through influence on other risk factors in children. In a study of
497 children between 2 and 18 years, blood lipids, blood pressure, and obesity were assessed. The children were evaluated
for the influence of blood pressure, and obesity on blood lipids
and lipoproteins. When the children were divided into normal
and prehypertensive-hypertensive groups based on sex, more
boys had HDL-C values less than 40 mg/dL, and more girls had
LDL-C values greater than or equal to 130 mg/dL. These results
suggest that lipids and blood pressure make independent contributions to cardiovascular disease risks in children (11).
To assess the impact of elevated blood pressure during
childhood on hypertension and the metabolic syndrome later in
life, 493 children with elevated blood pressure were followed
over several decades. Odds ratios of developing hypertension
and the metabolic syndrome were computed for each individual
at different stages of development during their lives. The results
indicated that boys who were hypertensive at age 5 to 7 years
were more than three times as likely to be hypertensive as
adults. Girls with hypertension at age 8 to 13 years were almost
twice as likely to develop hypertension as nonhypertensive
girls. Younger boys and girls with elevated blood pressures are
more than twice as likely to develop the metabolic syndrome
once they become adults (13).
Results from data on 11-year-old African American boys and
girls in our laboratory were generally consistent with results
published in the literature (10,11). The boys and girls were
measured for body composition, TC, HDL-C, and glucose, and
the variables were evaluated for relationships with each other
(Figure 2). The results indicate that blood lipoproteins and
glucose share low but similar relationships (r e 0.40) with body
composition as measured by both BMI and percent body fat
estimated from skinfolds. However, when BMI increased, there
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Figure 2. Relative relationships of BMI and percent fat with selected metabolic
syndrome and cardiovascular variables in children.
also was a trend for an increase in TC and glucose. The
relationships between blood pressure and body composition
variables are significant and similar for BMI and percent body
fat in the children. Unlike lipoproteins and glucose, which seem
to each make a significant independent contribution to the
development of cardiovascular disease in children, blood
pressure shares a significant relationship with body fat and
BMI. This suggests that the contribution blood pressure makes
to the development of cardiovascular disease is shared with or
influenced by body composition in children.
MANAGING THE METABOLIC SYNDROME IN CHILDREN
Recent data suggest that in children with the metabolic
syndrome, healthy lifestyle modifications should include weight
loss, regular physical activity, and careful monitoring of the
individual metabolic syndrome risk factors. Treatments should
be based on behavior changes designed to optimize lifestyle
modifications. A realistic goal for weight reduction is 7% to
10% of body weight. However, weight loss interventions with
children should be undertaken with care because growth and
development are necessary parts of maturation and may
complicate achieving desirable reduction in weight. Thus, body
composition assessments are helpful tools for managing the
obesity aspect of the metabolic syndrome in children (5,14).
Children who are sedentary should begin with low-intensity
exercise for relatively short periods and gradually increase the
length of participation during each session. For example, a child
could begin with a comfortable 10-minute walk and increase the
time over a 2- or 3-week period. Children should be encouraged
to reduce time spent participating in sedentary activities and to
develop more physically active lives by walking up stairs,
walking to events, and participating in lifetime physical
activities such as those listed in the Table. Physical activity is
not only associated with successful weight reduction, but also
can help reduce the progression to diabetes in children with the
metabolic syndrome.
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Obesity and the Metabolic Syndrome in Children
TABLE: Lifetime Physical Activities That
Promote Health and Wellness in Children
Activities With
Continuous
Movements
Activities With
Intermittent
Movements
Resistive
Activities
walking
dance dance revolution
calisthenics
jumping rope
dance
regular and
modified
push-ups
skating
camping
sit-ups/crunches
swimming
tennis
resistive training
with machines
cycling
canoeing
hiking
circuit games
soccer
aerobics and aerobic
dance
skipping
tag
Children and adolescents in the lowest quartile for physical
activity have more metabolic syndrome risks, such as insulin
resistance and low HDL-C, than children in the highest quartile
(5). Children should be encouraged to participate in a variety of
Photo by Jennifer Searcy courtesy of Franklin College.
physical activities, thus creating a more conducive environment
for regular participation.
Endurance, resistance, and lifetime physical activities such
as those listed in the Table should be part of the menu. Physical
activity recommendations should include practical, regular, and
moderate regimens of exercise, with a daily minimum participation time of 30 to 60 minutes. There seems to be a doseresponse between physical activity participation and the
metabolic syndrome. Children who exercise at heart rates of
about 150 BPM (roughly 6 METS) have reduced metabolic
syndrome risk factors. Therefore, health and fitness professionals
who find creative ways of encouraging children to participate in
physical activity at the recommended duration and intensity will
contribute greatly to metabolic syndrome management (15).
Healthy diets for children with family histories or who are at
risk for the metabolic syndrome also are effective interventions
(5). Recommended dietary intake for these children include at
least five fruits and vegetables a day; increased consumption of
whole grains; avoidance of sweets, sodas, and other emptycalorie foods; and a dietary fat content of no more than 30% of
total calories per day. These guidelines can be found online at
www.health.gov/dietaryguidelines/dga2000/document/frontcover.htm.
It is important when dealing with children to determine if
there is an underlying condition causing high blood pressure
and design a treatment of that condition. Obesity and overweight are risk factors that contribute to a rise in blood pressure
across all age groups. This is especially dangerous for children
because studies show that overweight children with high blood
pressure are much more likely to become adult heart disease
patients. Other conditions that may contribute to high blood
pressure include kidney disease and endocrine disorders (11,13).
SUMMARY AND CONCLUSIONS
Health and fitness professionals are knowledgeable of physical
activity participation and weight loss regimens, and can play an
important role in managing the metabolic syndrome in children.
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VOL. 12/ NO. 4
Similar to adults, this article indicates that obesity and insulin
resistance are the backbone of the metabolic syndrome in
children because both influence cardiovascular disease directly
and indirectly through other risk factors. In recent years, the
obesogenic culture experienced by many children has become a
major contributor to the metabolic syndrome. Elevated childhood blood pressure has been shown to be an effective predictor
of the metabolic syndrome later in life because it is associated
with abnormal blood lipids and lipoproteins.
Recognizing the relationships among the risks factors and
devoting efforts to control each risk factor is an important step in
reducing the prevalence of the metabolic syndrome in children.
In addition to the above interventions, changing behaviors so that
children participate more frequently in lifetime physical activities
and consume healthier diets will alter the obesogenic culture and
help minimize or eliminate the growth of this disease in children.
L. Jerome Brandon, Ph.D., FACSM, is a
professor and director of doctoral programs
in the Department of Kinesiology and Health
at Georgia State University in Atlanta, GA.
His research interests are obesity, the metabolic syndrome, and physical activity, especially with African Americans. He also has a
research interest that focuses on physical
function and aging.
Larry Proctor, Ph.D., is a member of ACSM
and an assistant professor in the department
of Health & Exercise Science at Louisiana
Technical University in Ruston, LA. His
research focus is community health and
fitness in African Americans as related to
wellness and obesity.
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rate of overweight among children aged 5 to 13 years in a district-wide
school surveillance system. American Journal of Public Health
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among US children, adolescents, and adults, 1999Y2002. JAMA
291:2847Y2850, 2004.
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2006.
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to improvement in BMI in children and adolescents. Obesity Research
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9. Swallen, K.C., E.N. Reither, S.A. Has, et al. Overweight, obesity,
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CONDENSED VERSION AND BOTTOM LINE
The metabolic syndrome is a fairly new health issue for
children that can be effectively managed with healthy
lifestyle choices such as physical activity, balanced diets,
and frequent checkups.
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