genetic/endogenous and environmental/exogenous factors contribute to the
development of a high degree of body fatness early in life (table 1). Twin studies
suggest that at least 50% of the tendency toward obesity is inherited [1–5].
There is also increasing body of evidence that responsiveness to dietary intervention
is genetically determined [9–12].
Several monogenic causes of obesity have been identified. Genetic alterations
of the ob gene (leptin) [13–17], the leptin receptor [18] as well as the
melanocortin-4 receptor (MC4-R) [19–21] have been shown to be associated
with severe obesity.
However, in most patients, a multifactorial etiopathogenesis contributes to
the development of obesity. Exogenous factors such as overconsumption of fat-rich
diets, the excessive use of modern media and in particular television viewing
[22–24] and lack of physical activity (sedentary life style) [25] are the most
important risk factors for the development of obesity in childhood and adolescence.
Nutrition and diet early in infancy is thought to influence growth rate and
body fatness beyond infancy. Taken the available data together, many authors support
a model in which susceptibility to obesity is determined largely by genetic
factors, but the environment determines individual phenotypic expression [1–5].
A BMI greater than 28 kg/m2 is associated with an increased risk of morbidity
such as stroke, ischemic heart disease, sleep apnea syndrome, orthopedic
diseases or type II diabetes mellitus in adulthood. Even more concerning are
data indicating that adolescents whose BMI had been greater than the 75th percentile
are prone to an increased risk of death from cardiovascular disease as
adults [1–5, 26].
The most common sequelae of primary childhood obesity are, among others,
hypertension, dyslipidemia and psychosocial problems (table 2), predisposing
for yet again additional comorbidity such as cardiovascular disease in early
adulthood. Approximately 60–85% of obese preschoolers will stay obese in
adulthood. Thus, the comorbidity represents a major health burden in industrialized
societies. In addition, childhood obesity seems to increase the risk of
subsequent morbidity whether or not obesity persists in adulthood [2, 3, 5, 26].
Recent studies indicate that impaired glucose tolerance is present in up to
25% of obese children, and type 2 diabetes can be identified in up to 4% of
obese adolescents [27].
Therapeutic Approaches
Multidisciplinary Treatment Options
Because obesity is a risk factor for numerous medical disorders, psychosocial
problems and excess mortality, it is indeed imperative that effective treatment
be developed and be widely available and instigated. Therapeutic
strategies should be multidisciplinary and should include psychological and
family therapy interventions [28], lifestyle/behavior modification [29], exercise
programs [25] and nutrition education [30] (fig. 1). In this context, the role of
regular exercise has to be emphasized [25, 31–35]. Intermittent exercise (high
intensity followed by low intensity sports) results in greater reduction in weight
and fat. Such approaches also increase compliance/adherence rates of the
youths. Optimal results are being achieved by combining programs to reduce
sedentary behaviors based on specialized, structured exercise prescriptions [33,
35–37].
Multidisciplinary outpatient treatments are considered to be the most
effective [33, 35]. Thus, networking of primary care physicians, public health/
school medicine institutions, specialists of pediatric and adolescent medicine,
social workers, child psychologists and dietitions as well as sport educators
should be achieved (fig. 1). Such networking concepts should be strongly supported
by health insurance providers and politicians. Using such approaches,
some groups have reported high success rates and sufficient long-term weight
reduction in small groups of children studied [33–37].
Lifestyle and Behavioral Modification
During the last years and even decades, physically inactive behaviors have
been increasingly promoted. Children walk less in order to get to school or to
play with friends. The home environment frequently does not allow our youngsters
to play in the streets or to do outdoor activities as safely as in the past.
Favorite leisure-time activities now include video and computer games as well
as television programs rather than physical exercise [38].
However, the significant increase of obesity in not only a result of changes
of individual lifestyle and habits, but also of general features in the industrialized
countries. Unfortunately, costs and availability of healthy foods vary around
countries and according to the time of year. Thus, ‘junk food’ is more easily
available and affordable to a growing number of individuals. It is essential that
local and national governments, schools, and supermarkets make healthy diets
and active lifestyles accessible and affordable for families all over the country.
Healthy living as well as individual health and nutrition education has to be
promoted by the government in order to stop the current epidemic of obesity in
the Western World [38, 39].
The fact that changes to a healthy lifestyle, including appropriate eating
patterns and exercise, is more easily incorporated into adulthood if learned
early in life strongly suggests that treatment of obesity as well as cognitive
awareness for a healthy lifestyle should start in childhood [40].
Psychological, Group and Family Therapy Interventions
For the treatment of childhood obesity, different strategies of psychotherapy
have been used, the most important of which are family or cognitive behavioral
therapy. The main goal of all psychotherapies is to create an awareness for
lifestyle changes.
The several types of psychotherapy should be chosen according to the age
of the obese individuals. As pre-schoolers normally accept groups formed from
outside, group teaching is a promising approach. In contrast, older children
prefer to create their own groups; therefore, individual treatment might be
preferable. As the family of origin is very important not only in early childhood
but also with teenagers and adults, family therapy can be helpful with all ages
of obese individuals [40].
As family members are normally closest to obese children and adolescents,
their emotional and psychological support is crucial for successful and lasting
changes of lifestyle in the context of obesity therapy. Thus, it is advisable that
treatment regimes should be adhered to by as many members of the family as
possible. Family arrangements to meet the obese child’s diet and exercise programs
should be accompanied by encouragement, sensitive support and appreciation
by family members. The positive effects of even slight weight loss can
encourage further pursuit of restrictive diets and further weight loss.
Exercise and Physical Activity
The enzymatic activity shows a characteristic profile in lean and obese
subjects. Obesity-prone subjects have decreased activity of fat-oxidizing enzymes
in skeletal muscles. Moreover, smaller areas of type 1 and type 2B muscle
fibers could be found in post-obese vs. non-obese individuals [41]. The hydroxyacyl
coenzyme A activity, a key enzyme in b-oxidation of fatty acids, is significantly
negative when correlated to relative adiposity [42]. These results
suggest lower fatty acid oxidation rates in obese individuals and might explain
the increased fat deposition in these subjects.
It is well established that an individual adapted to a higher level of dynamic,
aerobic motor activity during growth may develop greater activity in specific
enzymes which metabolize and utilize fatty acids. In addition, aerobic exercise
increases cardiorespiratory capacity. The utilization of fat metabolites during
muscle work is facilitated by the increased enzymatic activity of the skeletal
muscle. Thus, aerobic exercise is the most suitable form for obese children and
adolescents [42].
At the beginning of exercise programs, the interest of the obese child
should be focused on increased exercise and physical activity. The reduction of
body fat is best achieved by dynamic, aerobic exercise. Thus, it can be ideal to
start exercise programs with swimming, since these can help make movements
easier for those who are extremely obese. Later in the therapy program, after
some weight reduction and adaptation to increased physical activity, it might be
easier for the kids to exercise from lying down or sitting positions or to use
cycle ergometers [43].
Finally, exercise in the concept of obesity therapy not only aims to reduce
body weight but also to correct posture and to reduce comorbidity. As the need
of obese individuals as well as the degree of obesity and the social background
show a significant variability, it is essential to individualize and adapt each
exercise program according to the special features of the particular child.
Nutritional Education
As obesity is a multifactorial disease, diet is only one of several treatment
approaches. Dietary intervention should be related to the child’s age, the severity
of obesity and the presence of comorbidities. Evaluating the child’s nutritional
status is essential prior to prescribing any diet [44].
Children and adolescents with moderate obesity and no comorbidities can be
treated with a balanced low-caloric diet (BLCD). In a BLCD, the energy intake is
reduced by about 30%, balanced with 20% energy derived from protein, 30–35%
from fat and 45–50% derived from carbohydrates, respectively [44].
In patients with severe obesity (BMI far above the 97th percentile) and
who are already affected by secondary complications of overweight and obesity,
however, a very-low-calorie diet (VLCD) should be considered rather
than BLCD. In VLCD 800 kcal/day or fewer are provided [45]. The calories
can be either partially balanced (protein 25%, fat 30%, carbohydrates 45%) or
unbalanced (protein 66%, fat 24%, carbohydrates 10%). The latter is also
referred to as protein-sparing modified fast (PSMF), as it is supposed to spare
lean body mass while producing rapid weight loss. Severe obesity in childhood
and adolescence is most widely treated with PSMF [44]. However, since
VLCDs and PSMFs can produce rapid and remarkable weight loss, one has to
take into consideration that this can later lead to a ‘yo-yo’ syndrome of loss
and regain of body weight. Thus, these groups of diets should be used very
carefully in this age group of obese patients and only under strict medical
supervision.
In general, a nutrition plan has to be developed and discussed in accordance
with the obese individual’s specific needs and the child’s social background.
Pharmacotherapy and Available Compounds
Since the efficacy and success rates of the available treatment strategies for
obesity are very limited, long-term treatment including extended pharmacotherapy
may be necessary for some very obese adolescents [46–52].
However, anti-obesity drugs, i.e. appetite suppressants and thermogenic
drugs, have not been approved for use in children. Some centrally acting
noradrenergic agents and serotoninergic agents are being used to treat obesity
in adults. Thermogenic drugs are either epinephrine or caffeine or alternatively
atypical beta-adrenergic agonists. Digestive inhibitors such as lipase inhibitors
and fat substitutes have been used in children and adolescents in off-label use
and in only a few clinical studies.
Taken together, three main modes of action of anti-obesity drugs can be
distinguished: substances that act upon: (1) energy intake; (2) energy storage,
or (3) energy output. Agents which influence energy intake either act through
the brain by modifying eating behavior as well as suppressing appetite or exert
their actions by altering gastric emptying, causing malabsorption or relay satiety
back to the brain. Drugs that modify energy storage either decrease lipid
storage or increase lipid oxidation in the fat tissue. Lastly, energy output can be
regulated either in the brain or in skeletal muscle and brown adipose tissues
[47–49].
At present, two of the anti-obesity medications, orlistat and sibutramine,
are increasingly being used in adults. Orlistat binds to gastrointestinal lipases
and causes a partial inhibition of fat resorption from the gut. In contrast, sibutramine
causes a centrally mediated increase in satiety and energy expenditure.
When combined with a hypocaloric diet, both drugs lead to a moderate
additional weight loss of some kilograms within 6 months [47, 49].
Metformin is at present being studied as therapy for both type 2 diabetes
and obesity in children and adolescents. However, great care should be exerted
when anti-obesity medication is to be prescribed to adolescents or children
[3, 47]. Several previously widely used medications have recently been withdrawn
from the market because of concerns about side effects in adults. Most
if not all of these drugs have not yet been studied in respect to efficacy, safety
and long-term effects in children and adolescents [2, 3, 35, 46–52].
If one is to summarize all available data from clinical studies of anti-obesity
pharmacotherapy in childhood and adolescence it is clear that all therapies must
be considered within the framework of a multidisciplinary approach with the
support of an interdisciplinary team, including primary care physicians, public
health/school medicine institutions, specialists of pediatric and adolescent
medicine, social workers, child psychologists and dietitions as well as sport
educators [1–3].
Surgical Intervention
Laparoscopic adjustable gastric banding is being increasingly considered
as the treatment of choice in very obese adults [53, 54]. Early complications of
such interventions and significant late complications such as pouch dilatation
and stomach slippage have been rare [53]. However, in one series in 7.5% of
146 cases operated on reoperations were necessary [55]. Recommendations of
an international workshop on gastric banding for adult obesity are summarized
in the following: (1) good patient selection has to be made; (2) standard surgical
practice has to be adhered to, and (3), last but not least, no surgery must be
performed without the support of an interdisciplinary team which has to include
internists, psychologists and dietitians [53]. Whether or not such invasive treatment
options will ultimately be considered in adolescents is still open to debate.
Perspectives
Childhood Obesity as a Major Burden for the Economy
Obesity in childhood and adolescence has already become a major factor
in health care planning systems and within the health care industry. The financial
burden of childhood obesity for industrialized societies can only be estimated.
Approximately 70 billion dollars is the annual economic cost due to medical
expenses and lost income as a result of complications of adult obesity in the
USA. At least another 30 billion dollars is thought to be spent on diet foods,
products and programs to lose weight [56–59]. According to a recent report
by Fontaine et al. [56], the BMI associated with the greatest longevity is
23–25 kg/m2 for white and 23–30kg/m 2 for black adults. For any given degree
of overweight, younger people generally had a greater degree of years of life
lost than had older subjects. Since obesity apparently shortens life expectancy
markedly, especially among young adults, the economic loss for the society
already has become enormous.
The fact that obesity is associated with a significant increase in morbidity
and mortality and that obese people are often stigmatized both socially and in
the workplace contributes to the economic cost of obesity albeit in an unknown
and almost incalculable way [36, 59].
Prevention and Costs of Prevention
Prevention of obesity has to start very early in life, perhaps even before
extrauterine life [60]. A population and community approach for prevention
seems to be the most promising and reasonable. However, primary prevention
has been proven to be difficult or impossible in most societies at this point of
time [2, 3, 61]. Again, a multidisciplinary team approach is crucial to develop
and secure preventive strategies. Good nutrition and modest exercise for pregnant
women as well as monitoring of intrauterine growth of the child are mandatory.
After birth, rapid weight gain should be avoided and principles of good
nutrition and physical activities should be taught at all ages. Breast-feeding
should strongly be recommended [60]. Children’s food choice can be influenced
by early intervention and guidance. Parents should be encouraged to make healthy
foods easily available to the child and serve these foods in positive mealtime
situations in order to help their child to develop healthy food habits [61]. As for
treatment strategies, multidisciplinary teams should be formed. Such teams
should always include a physician, a nutrition specialist and a psychologist but
mainly consist of school nurses, teachers and kindergarten teachers. Joint actions
by physicians, health authorities and politicians both in the community and also
using modern media and mass media are being asked for to implement nationwide
prevention programs. Such programs have to take into account cultural and
racial preferences and attitudes in respect to food preparation and eating habits.
Taxes on fast foods and soft drinks should be considered, while nutritious foods
such as fruits and vegetables could be subsidized for the poorer income classes.
Nutrition labels should be required on fast-food packaging. Last but not least,
food advertisement and marketing directed at children should be banned while
funding for public-health campaigns for obesity prevention should be increased
[2, 3, 5]. Recent changes in federal tax laws in the United States may influence
the roles of health plans in promoting physical activity and thus may assist treatment
and prevention of obesity [57].
Conclusions
Obesity is the most common chronic disorder in industrialized societies
[9]. In some countries, the prevalence of juvenile obesity already exceeds that
of allergic disorders including both asthma and eczema. Its impact on individual
lives and on health economics has to be recognized by physicians and the
public alike.
Childhood obesity is associated with substantial comorbidity and late
sequelae. While diagnostic strategies are clear and straightforward, treatment
remains difficult and frustrating for the patient, family and the multidisciplinary
team caring for children and adolescents with obesity. In our opinion, much
more attention should be given to prevention and the development of preventive
strategies at all ages. Prevention should in any case start very early in life. Finally,
public awareness of the ever increasing health burden and economic dimension
of the childhood obesity epidemic has to be considered by the public and by
politicians.
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