Journal of Medicine Vol 2 - Amrita Institute of Medical Sciences and ...

Amrita Journal of Medicine
Obesity in Children and Adolescents
obesity in adulthood, but if both parents are obese, the
odds ratio increases to more than 10. Before 3 years of
age, parental obesity is a stronger predictor of obesity in
adulthood than the child’s weight status 13 .
NEUROENDOCRINOLOGY OF
ENERGY METABOLISM
Food intake and energy expenditure is controlled by
complex neuroendocrine interactions. The hormone leptin
is an important component of this complex system. Leptin
is made almost exclusively in adipose tissue and acts
centrally in the hypothalamus. Low plasma concentrations
of leptin and insulin (e.g., during fasting and weight
loss) increase food intake and decrease energy expenditure
by stimulating neuropeptide Y (NPY) synthesis, and
perhaps by inhibiting sympathetic activity and other catabolic
pathways 3 . High leptin and insulin concentrations
(e.g., during feeding and weight gain) decrease food intake
and increase energy expenditure through release of
melanocortin and corticotropin-releasing hormone (CRH),
among others. The major peptides that stimulate feeding
are orexins A and B, which are secreted by the hypothalamus,
and ghrelin, which is secreted by the stomach 3 .
VITAL PERIODS IN
DEVELOPMENT OF OBESITY
There are vital periods of development for excessive
weight gain. Intrauterine influences play a major role in
the genesis of obesity by influencing proportions of fat
and lean body mass, central nervous system appetite control,
and pancreatic structure and function.
Epidemiological studies have demonstrated a direct affirmative
relationship between birth weight and BMI
attained in later life 14 . In addition, lower birth weight for
gestational age has been associated with later risk for
more central deposition of fat, which also confers increased
cardiovascular risk. Rapid weight gain during
infancy is also associated with obesity later in childhood 15 .
The combination of lower birth weight and higher attained
BMI is most robustly associated with later CVD
risk 16 .
Extent and period of breastfeeding have been found to
be inversely associated with risk of obesity in later childhood
17-20 . The normal tendency during early puberty for
insulin resistance may be a natural cofactor for unwarranted
weight gain as well as various comorbidities of
obesity 21 . Early menarche is clearly associated with extent
of obesity, with a twofold increase in rate of early
menarche associated with BMI greater than the 85 th percentile
22 . The risk of obesity persisting into adulthood is
higher among obese adolescents than among younger children
13 . Observations suggest that up to 80% of overweight
adolescents will become obese adults 23 .
ENVIRONMENTAL RISK
FACTORS FOR OBESITY
Environmental risk factors for overweight and obesity,
including family and parental issues, are numerous and
complicated. Poor cognitive stimulation in the home and
low socioeconomic status predicts development of obesity
24 . Parental food choices influence child food
preferences 25 , and degree of parental adiposity is a marker
for children’s fat preferences 26 . Children and adolescents
of lower socioeconomic status have been reported to be
less likely to eat fruits and vegetables and to have a higher
intake of total and saturated fat 27-29 . Early rebound of the
BMI is associated with an augmented risk of higher BMI
in adulthood. A recent study links early rebound of BMI
to glucose intolerance and diabetes in adults 30 .
SOCIETAL CHANGES AND OBESITY
Widespread and intense societal changes during the
last several decades have contributed to childhood obesity.
Leisure activity is ever more sedentary and there has
Table 1: Adverse Outcomes in Childhood Obesity
Metabolic
Cardiovascular
Psychological
Orthopedic
Neurological
Hepatic
Pulmonary
Renal
Malignancy
Type 2 diabetes mellitus, impaired glucose tolerance
Metabolic syndrome, hyper insulinism
Dyslipidemia, atherosclerosis
Hypertension, left ventricular hypertrophy
Depression, poor quality of life
Slipped capital femoral epiphysis
Blount’s disease, osteoarthritis
Pseudotumor cerebri
Nonalcoholic steatohepatitis, gall bladder disease
Obstructive sleep apnea, asthma (exacerbation)
Proteinuria, FSGS
Of ovary, breast, colon
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