The global epidemic of obesity, now identified as a public health crisis, is barely a few decades old. Chronic food
shortage and malnutrition has been the scourge of mankind from the pre historic period, during which the major
diseases were pestilence and famine. Natural selection rewarded the "thrifty" genotypes of those who could store
the greatest amount of fat from a meagre amount of available food and release it abstemiously over the long run.
The capability to store surplus fat from the minimal amount of food consumed may have made the difference
between life and death for an entire species.
Thus, individual who could accumulate fat easily had an advantage
during evolutionary process. Increase in food supply became gradually possible only after the technological
advancements of the eighteenth century. Initially, the availability of food improved public health. But, the early and
favorable outcomes of technological advances did not withstand for too long. Eventually it turned detrimental, post
the second world war, due to excess of easily available and affordable food, coupled with reduced physical activity.
This provided the roots for obesity and accounts for its increased prevalence that is seen today.
Obesity: No more a sign of the healthy
World health organization (WHO) has defined obesity as an abnormal or excessive fat accumulation that may impair
health. This is a condition seen amongst all age groups in countries across the world. Obesity occurs as a result of
complex interaction between genetic, environmental and lifestyle factors. It has been declared as one of the most
neglected diseases of significant public importance by WHO.
Based on the distribution of body fat obesity can be of two types, android (masculine) and gynecoid (feminine).
The former shows predominant deposition of adipose tissue in the visceral and upper thoracic areas of body,
whereas the latter display fat accumulation in the lower part of the body.
Childhood obesity: Children too are not spared
Childhood obesity is commonly defined as weight being over 120% of the required weight as per height. The
prevalence of obesity among school children in India has been reported between 5.74% and 8.82% and it is
estimated that 200 million school children in India are either overweight or obese. Globally, the number of
overweight children under the age of five, is estimated to be over 41 million. Obese children are at increased
risk for a myriad of preventable acute and chronic medical problems, many of which are associated with increased
morbidity and mortality.
Causes
Obesity in children is attributable to various factors. The significant one being diet, genetics and inactive behaviour.
Intake of excess calories, regular consumption of fast food and sugary beverages along with larger portion size of
meal has been shown to contribute towards weight gain and obesity in children. Genetic factors including family
history of obesity and also certain behavioral factors like sedentary lifestyle and lack of physical activity can
aggravate the chances of obesity in children.
Consequences and comorbidities
Consequences of childhood obesity can be of 2 types: medical and psychosocial consequence.
Medical consequences.
They can be further classified into metabolic and mechanical complications. .
Mechanical complications
Obstructive sleep apnea and orthopediac problems are the two important mechanical complication associated
with childhood obesity.
Obstructive sleep apnea (OSA)
Deposition of fat results in anatomical distortion and narrowing of upper airway, thus making the obese individuals
more prone to obstruction during sleep when pharyngeal muscles relax in Rapid eye movement (REM) sleep. OSA is
associated with daytime somnolence and neurocognitive defects such as inability to concentrate memory lapse and
decline in learning ability, resulting from poor quality sleep.
Orthopedic disorders
Overweight and obese children are comparatively at greater risk of orthopedic complications. Obesity can predispose
to various orthopedic complications, including slipped capital femoral epiphysis (SCFE) and Blount disease. Blount
disease occurs due to overgrowth of the medial aspect of the proximal tibia and causes the lower leg to angle inward.
SCFE results due to increased force of the capital femoral growth plate causing a cartilage crack or slip that leads to
hip and knee pain. Overweight children are prone to fractures and display musculoskeletal discomfort, impaired mobility
and lower extremity malalignment. Obesity that continues into adulthood can lead to osteoarthritis and articular
cartilage breakdown.
Metabolic complications
It includes a range of disease or disorder occurring as a result of alteration of metabolism.
- Metabolic syndrome
It refers to a cluster of metabolic disorders comprising of hyperglycaemia, Hypertension, dyslipidaemia and visceral
obesity. The visceral fat enters the portal system and the free fatty acids induce significant insulin resistance at the
liver and muscles, and also leads to abnormal insulin secretion by the islet cells. Increased abdominal fat leads to
rapid, shallow breathing with subsequent increase in dead space ventilation and carbon dioxide accumulation.
The exact factor that trigger metabolic syndrome in obesity is not clearly identified.
- Gallstones
In obese children, the biliary excretion of cholesterol is increased relative to bile acid and phospholipid secretion,
thus increasing the likelihood of gallstone formation. Though, gall stone in children is most often associated with
an underlying condition such as haemolytic disease, obesity accounts for the majority of cases without underlying
conditions.
- Nonalcoholic fatty liver disease (NAFLD)
It is a spectrum of condition ranging from simple steatosis to steatohepatitis to frank cirrhosis. The disease
characterised by increased levels of hepatic enzymes and hyperechoic liver on imaging. Histological examination
of the liver shall reveal variable degrees of microvesicular and macrovesicular steatosis, and even periportal fibrosis
in severe cases. The underlying mechanism for NAFLD in obese children includes a combination of insulin resistance,
hyperlipidemia and increased oxidative stress. Insulin resistance results in elevated levels of insulin, further stimulating
the fatty acid synthesis in hepatocytes and also increased lipolysis leading to hypertriglyceridemia followed by increased
fatty acid uptake by liver cells.
- Polycystic ovary syndrome (PCOS)
Pediatric obesity and associated insulin resistance leads to increased susceptibility for PCOS. The prevalence of PCOS
in children increases in direct proportion with obesity. Sex hormoneproducing enzymes are expressed in adipose tissue,
excess central adiposity can thus lead to high androgen activity or hyperandrogenemia. This along with abdominal
obesity can lead to hyperinsulinemia and insulin resistance, in turn stimulating androgen and estrogen production by
the adrenal glands and the ovaries. In addition, lower levels of sex hormone-binding globulin (SHBG) in obese child
leads to further increase in the levels of free testosterone. This can further result in menstrual abnormalities such as
amenorrhea, metrorrhagia and polycystic ovary syndrome in obese girls.
- Type 2 Diabetes mellitus
Studies have proved that obesity driven type 2 diabetes might become the most common form of diabetes in adolescent
youth within 10 years. Though, type 2 diabetes mellitus had been considered as a disease of adults, the same now occurs
in increased numbers among obese adolescents. Both the conditions are associated with insulin resistance. The cornerstone
factor affecting insulin insensitivity is the release of nonesterified fatty acids (NEFAs) from the adipose tissue of obese
individuals. Increased release of NEFAs is observed in both type 2 Diabetes and in obesity, which in turn is associated with
corresponding condition of insulin resistance diplayed by them. It has been observed that shortly after an acute increase
of plasma NEFA levels, insulin resistance starts to develop.
- Cardiovascular disorders
Obesity predisposes an individual to variations in cardiac structure and hemodynamics. Obesity in combination with
excess adiposity can result in increased blood volume and cardiac output, thus causing cardiomyopathy. Two of the
most common cardiac comorbidity are dyslipidaemia and hypertension.
- Dyslipidaemia
In obese children, there is an elevation of serum low-density lipoprotein cholesterol (LDL-C) and triglycerides,
whereas, the levels of high-density lipoprotein cholesterol (HDL-C) declines considerably. In obese condition, an
increased synthesis of fatty acids by visceral adipocytes and hyperinsulinemia promotes LDL-C and triglyceride
synthesis by the liver, thus leading to dyslipidaemia.
- Hypertension
A combination of factors including insulin resistance, overactivity of the sympathetic nervous system, abnormalities in
vascular structure and function, activation of the renin-angiotensin mechanism leading to increased renal sodium
reabsorption and reduced natriuresis, may contribute to obesity-related hypertension in children. Obese children have
a 3-fold higher risk for hypertension, whereas overweight children (BMI > 75" percentile) have more than 8-fold risk of
developing hypertension.
Psychosocial consequences
These consequences are more prevalent than medical complications. Childhood obesity impacts the psychological
development of the child; discrimination and stigmatisation is often associated with negative characteristics. It has
been found to negatively affect academics and such children are more prone to being bullied. Individuals having a
history of obese childhood are more likely to have poor body image, low self-esteem and confidence. Mid-childhood
is the crucial period for development of body image and self esteem, thus an obese child may have fewer opportunities
in school, and smaller social circle. Increased psychiatric burden and poor psychological health make obese children
prone to thoughts and attempts of harming themselves.
Prevention
Prevention of childhood obesity is done at three levels, Primary, Primordial and Secondary respectively. The aim of
primordial prevention is to maintain a healthy weight and normal BMI throughout the childhood and into the teens.
Primary prevention intends to restrict the overweight child from becoming obese whereas Secondary prevention is
directed towards reversal of obesity and control of associated comorbidities. These can be put into practice sequentially
from perinatal period to adolescence.
Diagnosis
Even though vast spectrum of methods can help diagnose obesity, BMI is the simplest one. It is the height of an
individual correlated to the amount of body fat. As per the WHO classification, individuals with a BMI of 30 kg/m
or greater are obese. Other methods for diagnosis are
Skinfold thickness
It is a simple technique used by pediatricians to analyze fat distribution in the body. Although a trained person
is required to standardize the measurements, it is not mandatory for the person to have high degree of technical
skill. Usually, triceps skinfold which has a correlation with fat mass is measured and this along with BMI, provide
greater sensitivity in detection.
Bioelectric impedance assay (BIA)
BIA is a non invasive method of body composition assessment. The test involves the placement of two electrodes
and passage of low imperceptible electrical current through the body, which gives an estimate of body water. The
value obtained is further used in calculating the body fat.
Anthropometrics
Waist circumference or waist to hip ratios are robust indirect markers of intra-abdominal adipose tissue. Circumference
above 95 cm indicate elevated mortality and is also a predictor of cardiovascular and metabolic risk factors in obese
children Visceral or intra-abdominal adiposity is also associated with the metabolic syndrome in adults and children.
Anthropometric method becomes a significant tool in diagnosing childhood obesity as other techniques like skin fold
do not assess visceral fat.
Scarcity of food in the historical period had led to the connotations that being fat is a blessing and hence, plumpness
was considered as Bioelectric impedance desirable. Reflection of this was seen in the arts, literature, and medical
assay opinion of those times. However, by the end of 19 century, fat began to be stigmatized for aesthetic reasons
and by the 20" century, its link with increased mortality was identified. Today, obesity has become the bait to bring in
hundreds of maladies and it has not spared the younger generations too. Tackling childhood Obesity is the need of the
hour; it can be achieved through education, promotion of physical activity and healthy nutritional practices.
