|Year : 2012 | Volume
| Issue : 1 | Page : 4-14
Pediatric obesity: A portent of the diseases to come
Rakesh Kumar Sahay1, V Sri Nagesh1, G Preeti2
1 Department of Endocrinology and Metabolism, Osmania General Hospital and Osmania Medical College, Afzalgunj, Hyderabad, Andhra Pradesh, India
2 Department of Endocrinology and Metabolism, Niloufer Hospital, Institute of Child Health, Lakdi Ka Pul, Hyderabad, Andhra Pradesh, India
|Date of Web Publication||3-Dec-2012|
Rakesh Kumar Sahay
Department of Endocrinology, Osmania General Hospital, Hyderabad, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Pediatric obesity is one of the most important health issues facing the world today. Changing lifestyles, affluence on the rise, introduction to new diets, changing social order and an increasingly sedentary lifestyle of the youth have contributed to the alarming rise of child and adolescent obesity. Recent definitions of obesity by WHO and IOTF have afforded distinct cutoffs to determine prevalence of obesity at the community level in children. Newer insights into leptin and its signaling pathways have helped our understanding of the genesis of obesity, which has been further bolstered by the numerous studies into the genetics of obesity. Endocrine disorders like hypothyroidism, Cushing's syndrome, and syndromic disorders need to be ruled out. In addition to the routine investigations, evaluation of markers of insulin resistance and fat percentage is of great research utility In Indian children, who differ metabolically from children in the west. The cornerstones of treatment are therapeutic lifestyle changes, behavior modification and pharmacological therapy when needed. However, primordial prevention by inculcation of a healthy lifestyle seems to be the best bet in combating pediatric obesity.
Keywords: Lipids, metabolic syndrome, obesity, pediatric
|How to cite this article:|
Sahay RK, Nagesh V S, Preeti G. Pediatric obesity: A portent of the diseases to come. J Acad Med Sci 2012;2:4-14
| Introduction|| |
The new found affluence of India has also brought along with it, obesity and its ancillary problems, namely diabetes, dyslipidemia, cardiovascular problems, and host of other issues. This looming threat, has till date, remained largely unnoticed. Pediatric obesity and its auxiliary health problems are set to become the predominant chronic health problems in Indian children, especially in the more affluent ones who lead a westernized lifestyle. Obese children already constitute 25-30% of all children in the west and prevalence rates in India are probably similar. Over the next 20 years, type 2 diabetes will become a major component of pediatric diabetes unless steps are taken to curb it. Exogenous obesity constitutes a majority of the cases, while identifiable endocrinopathies are believed to comprise only a small minority of children referred for the evaluation of overweight, ranging from 2% to 3%. The increase in obesity prevalence among children is particularly alarming because obesity-related diseases rarely seen in children in the past, including obesity-associated sleep apnea, non-alcoholic fatty liver disease with resultant cirrhosis, and type 2 diabetes, are increasingly diagnosed in pediatric patients. The earlier onset of chronic health conditions such as type 2 diabetes in childhood has been shown to lead to an earlier onset of related medical complications such as end-stage renal disease.
| Prevalence of Childhood Obesity|| |
Among children and adolescents in India, the documented prevalence of overweight and obesity has ranged from 1 to 24%. ,,, There are very few nationally representative studies on the prevalence of and risk factors for overweight and obesity among youth in India. However, several small, non-representative studies (and a few city-representative studies) have recently examined the prevalence of obesity among specific populations of children and adolescents in India [Table 1]. ,,,,,,,,,
| Determinants of Childhood Obesity|| |
Rise in childhood obesity in the country has been associated with multiple factors like socio-economic status, genetic factors and cultural factors peculiar to India. The most significant among these factors are:
- Unhealthy nutrition: Spurred by advertisements, social networks, peer pressures, and availability of low cost calorie dense food, the Indian youth has been steadily gravitating to a diet composed predominantly of foods high in saturated fat and refined carbohydrates and sugar-sweetened beverages. Multiple studies have demonstrated the link between snacking patterns and obesity. A further cause of concern is the easy availability of such foods in the school canteens.
- Physical inactivity: Lack of green spaces, a steady pressure on children to perform in academics, reduced emphasis on physical activity, and lack of playgrounds in schools and gradual erosion of playtime by television and internet have contributed to this problem not just in India, but globally.
- Socioeconomic status (SES): In developed countries, SES is inversely related to childhood obesity, whereas in developing countries, affluent children are obese. Contributing factors include more consumption of junk food, availability of motorized transport for commuting to school and replacement of playtime by screen time.
- Socio-cultural factors: Myths like "a fat child is a healthy child," shortened duration of breastfeeding and early introduction of fatty complementary foods are also common in India.
- Television: Television viewing is perhaps the best established environmental influence on the development of obesity during childhood. There are several proposed mechanisms for this association which include replacement of physical activity, decrease in cues of satiety and promotion of junk food though product placements. Several studies have examined this association and found a significant association between television viewing and childhood obesity.
- Sleep: Association has also been suggested between shortened sleep duration and obesity or insulin resistance. While mechanism has not been elucidated, leptin and ghrelin pathways have been implicated.
- Genetic factors: They play a permissive role in childhood obesity. Genetic factors may be responsible for 30% to 50% of childhood obesity and adiposity,  but most of the genetic polymorphisms have not yet been isolated. A few syndromes have also been identified, which are mentioned in [Table 2].
- Endocrine disease: Endocrine causes are identified in very few children and adolescents with obesity and include Cushing's disease, both exogenous and endogenous, hypothyroidism, and growth hormone deficiency.
- Nutrition during gestation and early life: Maternal nutrition during gestation is an important determinant of metabolic programming. Individuals born small for gestational age (SGA) or large for gestational age (LGA), a mother's pre-pregnancy weight, gestational diabetes, breastfeeding, and rates of weight gain during infancy or early childhood are some of the factors implicated in determining metabolic programming.
Regulation of Energy Homeostasis
The existence of a tightly regulated feedback system can be demonstrated in long-term clinical studies of weight loss. Weight loss induced by very low calorie diets and/or behavior modification is rarely maintained over time. A similar phenomenon can be demonstrated in individuals that are overfed. These observations imply that most individuals have a genetically determined "weight set point." The weight set point is maintained in most individuals by adjustments to metabolic rate in response to changes in body mass. Obese individuals after weight loss require 10% to 15% fewer calories to maintain weight thus underlining the thrifty gene hypothesis. Further weight loss results in decline in total energy expenditure. A sustained decrease in caloric intake in overweight subjects eventually results in a new steady-state body weight, as the decline in daily energy expenditure achieves parity with the decline in energy consumption. It also causes increased appetite and difficulty in maintaining the lower caloric intake resulting in a return to the previous obese body weight set point.
Neuroendocrinology of Weight Regulation
Leptin is secreted from adipocytes in proportion to the degree of adiposity. It acts at the hypothalamus to inhibit feeding behavior, decrease insulin secretion, and increase metabolic rate. In experimental models, as weight increases, leptin levels rise resulting in decreased appetite and increased metabolic rate. Leptin signaling in the hypothalamus is primarily via receptors located in the arcuate nucleus. Leptin signals centrally by inhibiting neurons that contain neuropeptides (NPY and agouti-related peptide) that stimulate appetite and decrease metabolic rate. It also stimulates neuropeptides like pro-opiomelanocortin that inhibit and appetite that increase metabolic rate. appetite and increase metabolic rate.
Ghrelin, a hormone secreted by the stomach, stimulates NPY/AgRP neurons centrally. Ghrelin levels rise in the fasted state and decrease with feeding. Peptide YY (PYY) is secreted from the intestine. PYY appears to be upregulated with feeding. It inhibits NPY/AgRP neurons while stimulating POMC neurons. Insulin also appears to signal satiety via central nervous system (CNS) mechanisms similar to leptin.
| Hormonal Disorders Causing Obesity|| |
Growth Hormone Deficiency
It is commonly associated with visceral obesity and increases in the ratio of fat to lean body mass. Absence of appropriate height gain in the face of excessive weight gain should trigger an investigation of possible GH pathology.
Striae, easy bruising, and central fat distribution accompany glucocorticoid excess. Moreover, stature is almost always short in Cushings in contradistinction to exogenous obesity, where children are usually taller than their peers.
Increased fatigue, excessively dry skin, constipation, cold intolerance, poor scholastic performance, and short stature are some of the pointers towards hypothyroidism as a cause of obesity.
| Syndromes Associated with Obesity|| |
A few genetic syndromes associated with obesity are mentioned in [Table 2].
Consequences of Obesity
Increased adiposity can lead to both immediate complications in children and adolescents and long-term health consequences as adults. Insulin resistance almost always accompanies obesity and is directly related to the degree of adiposity. Many of the consequences of obesity, including impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM), dyslipidemia, hypertension, polycystic ovarian syndrome (PCOS), and acanthosis nigricans, are related to insulin resistance. In addition, obese children often suffer from psychosocial complications including depression and low self-esteem.
| Growth|| |
Obese children are usually above average height for age. Relatively tall stature is helpful in distinguishing children with simple obesity, since many of the congenital and endocrine conditions in which obesity is a common associated problem, namely hypothyroidism, Cushing's syndrome, growth hormone deficiency, and pseudohypoparathyroidism are associated with short stature. Tall stature is usually accompanied by increased skeletal size and often slightly advanced bone age.
With increasing average body fat, the age of puberty for boys and girls decreases. Obese girls have a lower age at menarche compared with non-obese girls. While bone age is advanced, it is never as advanced as in true precocious puberty and is usually only 1 - 1.5 years more than the chronological age.
| Orthopedic Problems|| |
Blount's disease in younger children and slipped capital femoral epiphysis in early adolescence are particularly associated with obese children.
Blount's disease is characterized by abnormal growth of the medial aspect of the proximal tibial epiphysis, which causes progressive varus angulation of the leg below the knee and is often bilateral. It is not very common. It is usually managed by weight loss and surgery.
| Slipped Capital Femoral Epiphysis|| |
This condition is also associated with hypothyroidism and growth hormone deficiency. The incidence is approximately 3 per 100 000 children. The condition usually develops insidiously with pain in the hip and limping. Children presenting with slipped capital femoral epiphysis (SCFE) before the age of 10 years should have thyroid function checked and be reviewed for other endocrine disorders.
| Gastrointestinal Problems|| |
Elevated concentrations of liver enzymes are another common obesity-related finding in children and adolescents.  Fatty liver is also a common finding in morbidly obese children, indicating increased storage and reduced delivery of triglycerides to the blood stream. All these abnormalities regress on weight reduction. Gallstones are also increased due to more cholesterol being excreted into the bile when compared to the excretion of bile acids and phospholipids. Indeed, when hemolytic disease is excluded, obesity accounts for the majority of gallstones in children and adolescents.
| Respiratory Problems|| |
Overweight has been associated with significantly more severe symptomatology in asthmatic subjects.  Obese asthmatic children have significantly lower peak expiratory flow rates than those with lower body mass indices (BMIs). Pulmonary-function tests show a high incidence of mild obstructive lung disease in obese children. Even in the non-asthmatics, obese children demonstrate more severe bronchial hyper-reactivity after exercise than their lean non-asthmatic peers with greater falls in forced expiratory flow rate in 1 second and lower peak expiratory and mid-expiratory flow rates.
| Sleep Disorders|| |
In most obese children, sleep disorders commonly observed are snoring but episodes and obstructive sleep apnea syndrome (OSAS). Mallory et al.  found that one third of 41 children with severe obesity reported symptoms of OSAS and one-third had some form of sleep disorder. There was evidence of severe OSAS in 5% of the children.
| Pseudotumor Cerebri|| |
Up to 50% of all children with Pseudotumor Cerebri (PTC) are obese. It usually develops before adolescence. Symptoms include pulsatile tinnitus, severe (occipital) headache, vomiting, and diminished vision. Papilloedema, sixth nerve palsy leading to diplopia, and paralytic squint are also observed. Neuroimaging is usually normal. The raised CSF pressure is secondary to raised intra-abdominal pressure leading to raised intrathoracic pressure. , Obesity associated with PTC should be treated promptly and aggressively by very-low-calorie diet (VLCD).
| Impaired Glucose Tolerance and Type 2 Diabetes Mellitus|| |
Previously considered an adult disease, a recent survey conducted in 2001 found that T2DM accounted for approximately 15% of diabetes cases among youths aged 10 to 19 years. The overall prevalence of T2DM in this age group was 0.42 per 1000.  Prediabetes or IGT, defined as a fasting glucose more than 100 mg/dL or a 2-h post-oral glucose load level between 140 and 200 mg/dL, is also becoming increasingly common in children and adolescents. They may report polydipsia, polyuria, nocturia, and nocturnal enuresis as indicators to the development of diabetes mellitus. The importance of severe insulin resistance for the development of T2DM is underlined by several large population studies: in the Bogalusa Heart Study, 2.4% of overweight adolescents, but no lean adolescents, developed T2DM by the age of 30 years.  Another study from Cincinnati  found that one third (19 of 58) of all new cases of diabetes presenting in 1994 aged 10-19 years had T2DM and over 90% of new diabetics had BMI above the 90th centile. The average BMI amongst the new patients with diabetes was 37 kg/m 2 and approximately 40% had BMI above 40 kg/m 2 . The underlying mechanisms for the relationship between obesity and T2DM are probably similar to those observed in adults: basal insulin secretion, stimulated insulin secretion, and insulin resistance relate directly to visceral fat mass and total body fat.
| Hypertension|| |
Primary hypertension in children and adolescents is now keeping pace with secondary hypertension and is also associated with other cardiovascular risk factors.  This can be mostly attributed to obesity, as obese children and adolescents have higher blood pressures and higher prevalence rates for hypertension than leaner children, with around 30% of obese children and 50% of obese adolescents affected. Prevalence doubles between the 75th and 95th BMI percentiles. Hypertension in these children is predominantly systolic. Age-related percentile charts usually have an arbitrary cut-off points of > 90th percentile for high normal blood pressure and > 95th percentile for hypertension. Hence, care should be taken to ensure usage of the correct blood pressure cuff (width and length) for accurate measurement of blood pressure in obese children.
| Hyperlipidemia|| |
The commonly observed abnormalities in the lipid profile of obese children are high total serum cholesterol, LDL-cholesterol, and triglycerides, and low HDL-cholesterol levels. The degree of obesity and abnormal lipid profiles show a more consistent association in males. In the Bogalusa Heart Study,  overweight during adolescence was associated with a 2.4-fold increase in the prevalence of total cholesterol above 240 mg/dl, a 3-fold increase in LDL levels above 160 mg/dl, and an 8-fold increase in HDL levels below 35 mg/dl in young adults (27-31 years). Visceral fat distribution is also associated with an unfavorable lipid profile. However, weight reduction can decrease, or even normalize, risk factor levels. Positive effects of weight reduction are more pronounced in patients with visceral fat distribution.
| Polycystic Ovary Syndrome|| |
Adolescent females with obesity often present with signs and symptoms consistent with hyperandrogenism and ovarian dysfunction, including amenorrhea or oligomenorrhea, acne, and hirsutism. Hyperandrogenism appears to primarily result from hyperinsulinemia. Low birth weight, above average birth weight, premature adrenarche, childhood obesity, and the metabolic syndrome are all independent childhood risk factors for the development of PCOS. Hyperinsulinemia-induced ovarian thecal androgen production and elevation of free testosterone are proposed mechanisms for PCOS. Insulin resistance is seen in at least 50% of adolescents with PCOS  and with greater prevalence in obese adolescents with PCOS. PCOS in young adolescents and young adults is associated with infertility and with longer term health risks including the metabolic syndrome, T2DM, and early coronary atherosclerosis. 
| Early Atherosclerosis|| |
Fatty streaks are present in the aorta by age 10 years and in the coronary arteries by age 20 years. Risk factors for atherosclerosis include high blood lipids, height, weight, tobacco smoke exposure, diabetes mellitus, and renal artery thickness as a measure of hypertension. The non-high-density lipoprotein (HDL) cholesterol concentration has a positive association with more extensive fatty streaks and raised lesions, and every 30-mg/dL increase in non-HDL cholesterol concentration is associated with increased atherosclerosis. HDL cholesterol is associated negatively with these lesions. Smoking, obesity, hyperglycemia, and hypertension also are associated positively with the presence of lesions even when lipid profiles are normal. Passive in utero exposure to a hyperlipidemic environment may program individuals for accelerated atherosclerosis.
Clinical characteristics of children requiring lipid screening: (i) BMI > 85% of age-/gender-specific value; (ii) a parent with a total cholesterol level > 240 mg/dL; (iii) a parent, grandparent, or sibling of a parent with cardiovascular disease (CVD) < age 55 years (including those undergoing coronary angiography with evidence of atherosclerosis, stent placement, balloon angioplasty, and/or coronary by-pass); (iv) hypertension; (v) Cigarette smoking; (vi) unknown family history. 
| Psychosocial Problems|| |
Psychological problems are common in obese children and include low self-esteem and difficulties in peer-group relationships. Obese adolescents also demonstrate high levels of anxiety, and disturbed body image which is far in far in excess of the general population.
| Adult Obesity|| |
A major consequence of childhood and adolescent obesity is adult obesity. Recent studies show that over 75% of obese children remain obese as adults, and that they are more obese than adults with adult onset obesity.  The later that overweight persists in adolescence and the greater the degree of overweight, the more likely it is that an individual will be an obese adult.
| History and Physical Examination|| |
History should include a review of previous growth records. A history of poor growth velocity despite increased weight gain is more consistent with hormonal disorders and genetic syndromes, while normal or increased growth velocity suggests familial obesity or exogenous obesity. Significant findings in the prenatal history include decreased fetal movement consistent with Prader-Willi syndrome (PWS). Birth history may reveal trauma possibly associated with an early CNS insult. Neonatal history of hypoglycemia and micropenis and/ or cryptorchidism may be associated with growth hormone (GH) deficiency. Failure to thrive in infancy and early childhood is associated with PWS. Delayed achievement of milestones, learning disabilities, and mental retardation may be associated with genetic syndromes of obesity.
Visual changes, severe headaches, and recurrent vomiting suggest a CNS lesion. Signs and symptoms of hypothyroidism, diabetes mellitus, and obstructive sleep apnea should also be checked. Menstrual history should be reviewed in adolescent girls.
Assessment of caloric intake, nutrient composition, feeding behaviors energy expenditure, maladaptive behaviors, food-seeking behaviors, appetite, eating habits, exercise, television watching, and exercise facilities are important in identifying areas for behavioral intervention.
The physical examination of the overweight child or adolescent should include blood pressure measurement at every visit, using an appropriately sized cuff. General body habitus should be noted, including a description of body fat distribution (apple versus pear body shape), as well as the presence of moon facies, buffalo hump, or any dysmorphic features. Tanner staging should be performed with attention to evidence of either precocious or delayed puberty. While precocious pubertal development might suggest the presence of a CNS lesion, delayed puberty is often seen in obese adolescent boys. Skin examination should include a search for acanthosis nigricans and skin tags seen primarily on the nape of the neck and in the axillae, reflecting insulin resistance), as well as documentation of striae or excessively dry skin. A neurological examination, including assessment of visual fields by confrontation, is necessary if a CNS lesion is suspected.
| Anthropometry|| |
Since the 19 th century, various indices have been proposed as measures of relative weight. These are as follows.
1. Body Mass Index: The weight-for-height index that is currently most used is the BMI, which is calculated as weight in kilograms divided by squared height in meters, or weight in pounds divided by squared height in inches multiplied by 703. Rohrer's Index (weight/height 3 ) has been proposed as a better weight-for-height index for adolescents during puberty, for consistency with adult definitions, and because BMI is more strongly correlated with adiposity in adolescence than is Rohrer's Index, BMI is used for assessment of obesity in children and adolescents, as well as adults. BMI also correlates well with measures of adiposity. However, the relationship between adiposity and BMI is nonlinear, and BMI is more highly correlated with body fat at greater levels of adiposity. 
A single BMI cut-off to define obesity in children and adolescents cannot be identified, because BMI changes as a child matures. Instead, growth charts based on population specific reference data are constructed and centile cut-points are chosen as indicative of overweight or obesity.
BMI reference curves for children and adolescents are available for an increasing number of countries, including, but not limited to, the USA, France, Japan, Italy, India, The Netherlands, and the UK. Although all these reference curves are of similar shape, the location of a particular centile will correspond to different BMI values. In order to facilitate global comparisons of trends in childhood and adolescent obesity rates, the International Obesity Task Force (IOTF) developed BMI centile curves based on pooled data for children and adolescents aged 2-18 years from nationally representative surveys conducted in Brazil, Great Britain, Hong Kong, The Netherlands, Singapore, and the United States. Centiles corresponding to a BMI of 25 and a BMI of 30 at age 18 were fit to the data. Unlike other pediatric BMI references, the IOTF curves have continuity from childhood into adulthood.
2. Identifying the appropriate chart: Between 1997 and 2003, the Multicenter Growth Reference Study was conducted by the World Health Organization (WHO) to develop standards against which to assess child growth. A large sample of healthy children who were breast fed, of high socio - economic status, and had mothers who did not smoke were studied in six countries. Based on these data, the WHO Child Growth Standards were developed to describe optimal growth in infancy and early childhood, which included BMI-for-age growth charts.
Since, well-nourished Indian children over the past two decades have been showing an increasing trend in somatic/physical growth as established by anthropometric measurements, a need for developing separate charts for Indian children was also felt and hence standards were developed in 2001 by Agarwal et al., which are now the reference standards most commonly used in India.
A recent study by Stigler et al.  compared (a) Agarwal's growth reference specific to India; (b) an international reference recommended by the International Obesity Task Force (IOTF); and (c) a new international reference recommended by the World Health Organization (WHO). In the study, the IOTF reference consistently classified participants in a lower weight status group, across all categories, compared to the new WHO references and Indian references and thereby underestimated obesity. Moreover, IOTF indices did not include Indian data. While the WHO reference includes Indian data and did perform better than the IOTF reference, it still underestimated the true extent of obesity in school going youth in India. The Indian reference standard performed best across all ages, as a BMI reference standard. It also used the 85 th and 95 th centiles to define overweight and obesity, respectively.
Having a BMI above the 95 th percentile of the growth reference increases the risk of obesity persistence into adulthood and is linked with elevated cardiovascular risk factor levels, such as blood pressure, cholesterol, and blood glucose. Recent evidence has linked the 85 th percentile BMI-for-age to obesity persistence throughout childhood, elevated levels of cardiovascular risk factors in childhood and adolescence, and risk for heart disease in adulthood.  Hence, a BMI cut-off > 85 th centile has been used to define overweight and 5th centile to define obesity.
3. Waist Circumference: Waist circumference (WC) is simple and effective way of measuring abdominal obesity in adults and children, without resorting to expensive techniques like CT and MRI and may be a better predictor of CVD risk than BMI in adults and children. In particular, WC is a better indicator of visceral fat than BMI in children. WC in conjunction with BMI is a better predictor of metabolic risk than either measure alone. Despite the strong association between BMI and total fat, the use of BMI as an indicator of adiposity in youths is tempered by the child's variation in growth rates and puberty. Studies , have also demonstrated that WC is associated with fasting insulin, blood pressure, and insulin resistance index in obese girls. Waist circumference during the past 10 to 20 years in youths has increased much faster than BMI over the same time period, thus proving to be a better predictor of rapidly changing obesity trends. In prepubertal children systolic and diastolic blood pressure, as well as apoA1: apoB, total cholesterol, and HDL-cholesterol have been shown to be significantly associated with WC, independently of age, gender, and BMI. Thus, a broad range of evidence in children of all ages suggests that WC is strongly associated with obesity-related morbidity and is a useful measurement to identify children at risk, and one which is easily reproducible.
4. Waist Height Ratio: There is a strong positive correlation between height and WC throughout growth, throughout childhood and into adulthood although the precise influence of height on WC remains quantitatively unclear. Hence, the waist height ratio (WHtR) has been proposed as a simple indicator of excess abdominal fat accumulation, with a cut-off or boundary value of WHtR ≥ 0.50 defining those with excess abdominal fatness. This measure has been proposed to be equally appropriate for use in adults and children, in both boys and girls and at all ages >5 years. A few studies have demonstrated the WHtR to be superior in its ability to predict CVD risk factors compared with BMI or percentage body fat. , A recent examination of WHtR in British children has shown that the percentage of children with a WHtR above the boundary value of 0. 50 has increased in recent years,  similar to the changes shown by WC.
5. Waist Hip Ratio: Men with a WHR of 1 or more and women with a WHR of 0.9 or more are considered to be at increased cardiovascular risk. Similar definitions have not been developed for children although they, too, are at increased risk of CVD if they have abdominal adiposity. Very few studies have been done regarding W/H ratio in children. The results have also not been uniform. One study of 127 children and adolescents aged 9 to 17 years, found correlations between abdominal fat distribution and triglycerides, HDL cholesterol, systolic blood pressure, and left ventricular mass.  However, other studies have found waist circumference and WHtR better indicators of central adiposity and cardiovascular risk than WHR.
6. Wrist Circumference: A manual measure of wrist circumference was more closely linked to insulin parameters than BMI in a cohort of overweight or obese children and adolescents, according to new study.  The study also evaluated standard deviation score BMI, fasting biochemical parameters, and homeostasis model assessment of insulin resistance in the study population. Wrist circumference was significantly linked with the parameters of insulin levels (β = 0.34) and homeostasis model assessment of insulin resistance (β = 0.35).They concluded that their findings suggested a close relationship among wrist circumference, its bone component, and insulin resistance in overweight/obese children and adolescents, opening new perspectives in the prediction of CVD. While further studies are needed, this parameter might serve as an easily measurable predictor of CVD in the future.
| Measures of Body Composition|| |
Measurement of body composition, particularly body fat, assumes importance because fat is the major source of stored energy in the body and a good indicator of nutritional state. The methods used to measure body composition differ in their accessibility, accuracy, cost and use of radiation, and are as follows.
1. Skinfold thickness: Measurements of multiple skinfold thickness are used widely because the technique is noninvasive, inexpensive, and easy to perform. However, measurements of skinfold thickness often are less accurate than are measurements of height or weight, particularly in obese subjects.  One study compared the agreement between eight widely used skinfold thickness equations and the value obtained on the basis of measurements of body density, body water, and bone mineral content. The use of skinfold measurement calculations over- or underestimated individual fat mass by approximately 10%.  The most commonly used skinfold measurement is that of the triceps.
The mid-arm muscle circumference (MAMC) can be calculated from the triceps skinfold (TSF) and the midarm circumference as follows:
MAMC = MAC - (3.1416 × TSF) 
The measured values for TSF and MAC and the calculated MAMC are compared with reference values. Values greater than the 90 th percentile for age are consistent with obesity.
2. Bioelectrical Impedance Analysis: Bioelectrical impedance analysis (BIA) involves measuring the fat and fat-free matter of the body by using a weak electrical current. The lean tissues of the body, because of their dissolved electrolytes, are the major conductors of electrical current, whereas body fat and bone are relatively poor conductors. Thus, BIA primarily measures total body water from which an estimate of FFM is obtained. BIA frequently is used because it is noninvasive, portable, and inexpensive. However, placement of the electrodes must be accurate. In addition, BIA is influenced by sex, age, disease state, and level of fatness.
3. Dual-energy X-ray Absorptiometry: Dual-energy x-ray absorptiometry (DXA) estimates FFM, body fat, and bone mineral density by using the differential absorption of x-ray or photon beams of two levels of intensity. In children, the scan takes approximately 10 mins. The average radiation dose is less than the average exposure of a chest radiograph. DXA is still not readily available in the clinical setting and the technique is limited because estimates of fat mass become less accurate as the individual's trunk thickness increases.
Other methods to measure body fat percentage include hydrodensitometry, air-displacement plethysmography, isotope dilution, neutron activation analysis, and total body potassium, but are usually applied only in research settings.
| Diagnosis|| |
Investigations in evaluation of obesity in children are mainly directed at diagnosing endocrine disorders and syndromic causes of obesity and evaluating the complication status of obesity. The basic evaluation of all overweight children and adolescents should include routine evaluation for renal and hepatic status, hemogram, blood sugars, fasting lipid profile, and wrist X-ray for bone age. T4 and TSH should be checked to rule out hypothyroidism. While hypothyroidism alone generally leads to only modest weight gain and does not result in severe obesity, subclinical hypothyroidism will compromise efforts at weight loss.
Other investigations include a fasting insulin level and free testosterone level when polycystic ovary syndrome is suspected, gonadotropins in the case of precocious or delayed puberty, tests of cortisol secretion to rule out Cushing's syndrome and a karyotype, and other genetic screening if a syndrome is suspected. If the history is suggestive of sleep apnea, polysomnography is advisable. Other studies such as videotaping and nocturnal pulse oximetry are of variable utility. If sleep apnea is present, an ECG and 2D Echo for right ventricular hypertrophy may be indicated.
Insulin resistance in children can also be detected biochemically by elevation of fasting insulin, retinol-binding protein, HOMA-IR, and a fall in adiponectin and IGF-1 levels. hs-CRP is also a sensitive marker of vascular inflammation.
Treatment of overweight and obesity in children remains challenging, especially when obesity is inherited and children are resistant to lifestyle changes. Options for obesity include diet, exercise, weight loss medications rarely, behavior modification, drug therapy when indicated for dyslipidemia and very occasionally, bariatric surgery. The main emphasis is on caloric restriction, exercise, and behavior modification. However, caloric restriction should not be so severe as to restrict growth.
The debate of low fat versus low carbohydrate diets continues. The low-fat diets result in less favorable lipid profiles. There may also be a shift to smaller more atherogenic LDL particles with low-fat diets. Diets high in carbohydrate and low in fat result in increased hepatic lipogenesis and increased triglycerides.
On the contrary, high fat diets cause less satiety than high-carbohydrate diets and such diets may promote over eating, resulting in a positive energy balance. High fat diets are also more energy dense and have less fecal energy loss.
Hence, it is difficult to recommend any one particular diet as each type of diet has its advantages and demerits. The main emphasis should be on a diet which provides sufficient dietary caloric restriction while providing adequate protein to ensure ideal growth. Due consideration should also be given to the lipid profiles and other co-morbid conditions while planning a diet. Refined sugars and fructose rich foods should be avoided.
Diets in isolation are relatively ineffective in severe obesity. Very low energy diets with a restricted energy intake of 600 to 800 kcal per day with 1.5 to 2.5 g of high-quality protein per kilogram of ideal body weight, multivitamin supplementation and carbohydrates 20 to 40 g per day may be useful. A minimum for 1500 ml of free water is also essential to avoid dehydration. These diets should be continued for a maximum of 12 weeks and are prescribed only in the severely obese children, especially when rapid weight loss is needed. Problems associated with the rapid weight loss include hyperuricemia, cholelithiasis, decreased serum proteins, orthostatic hypotension, diarrhea, and halitosis. The long-term efficacy of such diets is contentious.
Reducing consumption of sugared beverages (e.g. soda, juices and fruit drinks, and sports drinks) may be an effective way to reduce ingested calories. Decreasing calorie intake by consuming more fruits and vegetables instead of dietary fat can decrease the risk of developing obesity and T2DM. Plant-based dietary patterns should be encouraged for optimal health and environmental benefits.
Children and adolescents should be encouraged to participate in at least 45-60 min of moderate intensity physical activity (either sports or bicycling) most days of the week, preferably daily. This has been emphasized in a recent consensus statement on physical activity for Asian Indians.  Physical activity may be introduced into the children's daily schedule in various forms like: (1) School-based physical education: This aspect has consistently been neglected in India. Physical education helps not only in reducing obesity, but also in enhancing self esteem and academic performance. Activities should be individualized to suit cultural mores and local practices. (2) Community involvement: Community involvement by provision of parks and summer camps should be encouraged at the local government level. (3) Parental involvement: Parental involvement is necessary to ensure continuing physical activity in children. Parents should be encouraged to set an example for children, by exercising regularly and to ensure that children receive adequate time off from academic activities. (4) Safe routes to school for walking/bicycling: Creation of safe pedestrian pathways and enhancing neighborhood safety are long-term goals in this respect.
This includes reducing television and other screen time and increasing physical activity, training to motivate a change in eating behaviors or exercise, family counseling to support weight loss goals, and school-based changes to promote healthy eating and physical education. These can also include group sessions and also one on one counseling. Parent-focused behavioral interventions seem to be more effective. Maintenance of weight loss is sustained by continued behavioral management strategies as opposed to short term strategies. Government support is also necessary for providing civic amenities like playgrounds for promoting exercise. Incentives to schools which promote all round development, especially in the physical sector should be encouraged by the government.
Unfortunately, the long-term success of lifestyle intervention alone has been disappointing. This may reflect the resistance of energy dense feeding and exercise behaviors to change as well as the power of social and economic forces that shape lifestyles [Table 3].
Most drugs are unsuitable in children. Orlistat (approved for treatment of obese children over the age of 12 years) inhibits pancreatic lipase and thereby increases fecal losses of TG. The drug reduces body weight and total and LDL cholesterol concentrations. Side effects are minimal as long as subjects reduce fat intake but vitamin A, D, and E concentrations may decline and multivitamin, Calcium and Vitamin D supplementation may help to prevent osteopenia.
Metformin acts by reducing fasting or post-prandial insulin concentrations. Its major site of action is the liver. Through activation of AMP protein kinase, the drug increases hepatic glucose uptake and fatty acid oxidation, decreases gluconeogenesis and reduces hepatic glucose production. A few studies in adolescents have shown that metformin caused small but significant reductions in BMI (0.9-1.26 kg/m 2 ) and fasting insulin concentrations and increased insulin sensitivity.  Stores of deep abdominal subcutaneous fat, which may function metabolically like visceral fat, were selectively reduced. It also reduces central obesity, free testosterone concentrations, and hirsutism scores and increases ovulation rates in adolescents and adults with PCOS, most of whom are overweight or obese. It may also reduce the serum concentrations of ALT, a marker of hepatic dysfunction, in obese insulin-resistant adolescents.
Octreotide binds to the somatostatin-5 receptor and thereby impairs closure of the b-cell calcium channel, reducing glucose-dependent insulin secretion. However, need for parenteral administration, cost of the medication, and the drug's side effects preclude use of the drug.
It is an anticonvulsant that blocks voltage-dependent sodium channels, enhances the activity of the GABA receptor, and antagonizes a glutamate receptor other than the N-methyl-d-aspartate receptor. Topiramate may induce insulin sensitivity in the muscle, liver and in adipocytes Anorexia and weight loss occur early in 10% to 40% of children treated with topiramate for seizures. There are no studies of topiramate in childhood obesity. Its use as an anti-obesity agent is limited because of drowsiness and interference with cognition.
Ciliary Neurotrophic Factor
Ciliary neurotrophic factor (CNTF) is a neuroprotective polypeptide hormone with actions limited mostly to the CNS, where it acts by stimulating neurotransmitter production. Its weight loss action was first studied in patients with amyotrophic lateral sclerosis. It mimics the actions of leptin while overcoming resistance to it, and it has several other inflammation-related effects that may play a major role in obesity management.
In addition to these, leptin, ghrelin, PYY, amylin, GLP-1 agonists, DPP-IV inhibitors, lorcaserin and obestatin are also being studied. A panel of expert advisers to the Food and Drug Administration (FDA) recently voted to recommend approval of Lorcaserin, with certain restrictions and patient monitoring. The restrictions include patients with a BMI of over 30, or with a BMI over 27 and a comorbidity like high blood pressure or type 2 diabetes. However, final FDA approval is still pending.
Pharmacotherapy should be reserved for obese, rather than overweight, children. Pharmacologic agents may be considered only when obesity and comorbidities persist despite formal counseling and effort at diet and exercise.
| Treatment of Dyslipidemia|| |
Therapeutic Lifestyle Recommendations
Diet is the initial management for all children and adolescents who have dyslipidemia, including all those who have LDL cholesterol levels of 100 mg/dL or higher. If there is little improvement in elevated LDL cholesterol after using the general population diet for 3 months, a more aggressive dietary approach is necessary. In these children, the saturated fat should be limited to less than 7% of the total daily calories, and the dietary cholesterol intake should be less than 200 mg/d. The American Heart Association recommends an adequate trial of diet for at least 6 to 12 months along with lifestyle changes.  These guidelines should be followed by the entire family.
| Treatment Caveats|| |
Children aged 7 years or more with a BMI greater than the 95 th percentile for age should be considered for interventions. However, the terms overweight and obese should preferably be avoided in children as they are pejorative. The American Academy of Pediatrics expert panel has recommended assessing risk factors for these patients, including family history, trends in the patient's weight gain, their fitness level, and the distribution of adipose tissue versus lean mass to determine the need for intervention.  Additionally, the American Academy of Pediatrics expert panel, noting that younger patients have the benefit of significant future vertical growth, has suggested such growth can compensate for weight already gained; therefore, the goal for young patients (particularly those aged less than 5 years) is weight maintenance to allow the height to attain the same percentile as the weight.
Drug treatment is reserved for those at highest risk, namely children at least 10 years of age who have LDL levels of 190 mg/dL or higher or of 160 mg/dL or higher and other risk factors such as diabetes mellitus, end-stage renal disease, or multiple other major risk factors such as tobacco use, hypertension, or severe obesity after a trial of TLC [Table 4]. Statins are the only medications which have substantial data. In girls, the medications preferably should be started after menses, and a Tanner stage of II or higher is preferred. Treatment at younger ages is considered for homozygosity for LDL receptor deficiency. However, there are no clear guidelines for the appropriate age to start medications and each case should be considered individually. A recent American Academy of Pediatrics statement, however, has suggested that statins can be started at 8 years of age.  The statins approved for adolescents by the FDA as a result of studies showing up to 2-year efficacy and safety include lovastatin, simvastatin, pravastatin, and atorvastatin. Statins are contraindicated in pregnancy, and adolescent females need to be counseled about pregnancy prevention while taking the medication, although the evidence for significant teratogenic effects is limited. CNS and limb defects have been reported in newborns exposed to statins in utero.
Elevated triglyceride levels should be considered for therapy in children at risk for pancreatitis, such as homozygotes for lipoprotein lipase deficiency, or for children who have multiple cardiovascular risk factors. Bile acid-binding resins are the treatment of choice. Niacin is used rarely in pediatric patients. The same is true of fibrates. There have been a couple of studies with ezetimibe, but it is rarely used except in patients intolerant of statins. Omega-3 fatty acid supplements may be useful as primary agents in the treatment of elevated triglyceride levels, but no clinical trial data in children is available.
Prevention of Obesity
Prevention of obesity is centered on inculcation of good dietary habits, physical activity, appropriate behavioral training, and maintenance of these habits. A low-fat, low-cholesterol diet rich in fruit, vegetables, whole grains, and lean protein is recommended for all children over the age of 2 years. The diet should be low in saturated fat (<10%) and cholesterol (<300 mg/d). Trans-fats or partially hydrogenated oils ideally should be eliminated from the diet or should comprise less than 1% of total calories. Children over the age of 2 years should be encouraged to consume low-fat (1%) or nonfat milk and low-fat dairy products. Dietary fat should not be restricted in children younger than 2 years. Breastfeeding is recommended for infants.
Physical activity in youth should include at least 60 min of moderate to strenuous activity daily. Screen time, including television, video games, and hand-held games, should be restricted to 2 h or less a day. Provision of playgrounds and facilities for good physical education should be encouraged at the school and college level.
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[Table 1], [Table 2], [Table 3], [Table 4]