The Use Of Children Overweight Screening Criteria, The Appetite Regulation Of Overweight Children

There has been a significant increase in both the prevalence andseverity of obesity in Chinese population during the last two decades,and especially in children. The prevalence of child obesity, screened byweight-for-height criterion, is about 10%, North high, South low, but allpresent the upward trend.Multiple studies have shown that adiposity in childhood is correlatedwith the rising incidence of the classic cardiovascular risk factors,such as hypertension, hyperlipidaemia, hyperinsulinaemia, and earlyatheroesclerosis, as well as other health conditions including type 2diabetes, menstrual abnormalities, sleep-disordered breathing, andpsychosocial effects. These risk factors may operate through theassociation between child and adult obesities, and they may also actindependently. Because of their importance, the trends in child obesityshould be closely monitored. Trends are, however, difficult to bequantified or to be compared internationally, as a wide variety ofdefinitions of child obesity are in use, and yet, no commonly acceptedstandard has emerged.In 2003 the Group of China Obesity Task Force has recommended the useof the Body Mass Index Reference Norm for Screening Overweight and Obesityin Chinese Children and Adolescents to classify overweight and obesechildren. Depending on the use of new criteria, the obesity prevalencealteration and the practical problems that may arise should be comparedand analyzed.As the overweight and obesity have become the major public healthissues, there has been a remarkable progress in understanding themolecular mechanisms of food intake and energy homeostasis. This is duein large part to the increased research activity towards combating therising incidences of obesity. As a result, it had been well established that the central nervous system play an important role in controlling theenergy balance. Some studies have suggested, in central energy balanceregulatingcircuits, upstreamelements including the hormones leptin andinsulin are hormones, mainly secreted from adipose tissue and thecells of the pancreatic islets. Based on the observations on rodents,leptin and insulin have the similar central catabolic effects on energyhomeostasis, in which leptin and insulin crosses the blood-brain barrier,interacting with specific receptors in the arcuate nucleus of thehypothalamus, reducing food intake, stimulating thermo genesis andinduces weight loss. So far, it has not yet been shown in obesechildren,how leptin, insulin and appetite interrelate to each other.Adiponectin is a protein, secreted from adipose tissue. Studiesshowed that plasma adiponectin levels correlated negatively with theinsulin resistance, and the treatment with adiponectin can lower thecirculating glucose levels without stimulating insulin secretion,reducing body-weight gain, increasing insulin sensitivity and decreasinglipid levels in rodents. Thus adiponectin may also provide protectionagainst insulin resistance. This has importance for reducing insulinresistance in humans. At this time, a more complete understanding of thebiology, actions, and regulations of the adiponectin in human body (normaland obese) is needed.This is a descriptive population-based study; the site is inZhang-jia-gang city, Jiangsu province. The purposes of this study are tocompare the prevalence differences of overweight and obesity among schoolchildren, which determined by two different criteria: theweight-for-height criterion and the new body mass index criterion. Toassess the liver functions and the plasma lipids of obese childrenscreened by two criteria; to evaluate the two criteria and to summarizethe practical issues that should be informed during the use. This studyis also designed to investigate the appetite, plasma leptin, insulin andadiponectin in obese children. The purposes are to study the correlativitybetween appetite and the peripheral energy signals (leptin, insulin); toanalyze the relationship between serumlevelsof leptin, insulin and bodyheight, weight of obese children; to research the affects of adiponectin on liver functions and other parameters in obese subjects. The majormethods and results are as follows:1. The cross-sectional study examined 5,312 students from four gradesin three primary schools to two grades in two high schools inZhang-jia-gang city, Jiangsu province. During the annually students'physical examination, obese children and adolescents are screened by theweight-for-height criterion andthe new body mass index criterionaccording to their weight and height respectively. Screened by theweight-for-height criterion, the overweight rate and the obesity rate are15.47%and 7.59% in total, 21.07% and 10.70% inmale, 10.14% and 4.63%in female. And screened by the new body mass index criterion, theoverweight rate and the obesity rate are 9.89% and 3.41% in total, 14.04% and 4.66% in male, 5.94% and 2.22% in female. These results imply theprevalence of child obesity, screened by new BMI criterion, will lower1/2.2. The 14 items of liver functions and plasma lipids are measured.280 obese children are screened by the weight-for-height criterion (boys186, girls 94) and 125 obese children are screened by thebody mass indexcriterion (boys 85, girls 40). All of the later is included in the former.In the abnormal items, 7 items in 125 obese children who screened by newBMI criterion and 5 items in 155 "obese children" who excluded by BMIcriterion are significantly higher than the control children. Theabnormal rates are 10.4%～26% in the former and 3.2%～15.6% in the later.These results mean that the new BMI criterion is more stringent than theweight-for-height. Less than a half of obese children who screened byweight-for-height are taken for obese children by new BMI criterion, theoverweighed children who screened by BMI criterion also have abnormalliver functions and plasma lipids.3. A paired design study is carried out on the obese children. Bodyheight, weight, serum leptin and insulin are all measured. The serumleptin (Wilcoxon rank-sum test Z=7.542ng/ml, P=0.0000)and fastinginsulin(Z=5.414μIU/ml, P=0.0000) are higher and insulin action index(IAI=1/(FPG×FIns))(Z=5.487, P=0.0000) is lower in the obese childrenthan the control children. In boys, leptin shows a Spearman positive correlation with insulin (r_obese=0.42, P=0.0006; r_normal=0.45, P=0.0002),and correlates negatively with age (r_obese=-0.26, P=0.0334; r_normal=-0.32,P=0.0087) and insulin action index (IAI) (r_obese=-0.32, P=0.0084; r_normal=-043, P=0.0004) in both obese and normal children. In the boys withnormal body weight, the serum leptin and insulin are negative correlatedwith body height (r_lep.+H=-0.27, P=0.0304; r_lep.+W=-0.27, P=0.0300)and weight (r_ins+H=-0.26, P=0.0399; r_ins.+W=-0.28, P=0.0299). Thesenegative correlates do not show in obese children. This may be the causeof the differences of development between the obese and the normal-weightchildren.4. A paired design study is carried out on obese children. Appetite(bad=1, general=2, good=3, best=4), meal size (g./day) and eatingstyle (slow=1, middling=2, fast=3) are obtained by a questionnaire.No significant correlation existed between the meal size and serum leptin,and fasting insulin. These results indicate that leptin may selectivelyaffects the mechanisms controlling meal size in children. Subdividedaccording to appetite and eating style, serum leptin and fasting insulinvalues are up with the increase of appetite (with leptin r=0.26, P=0.0098; with insulin r=0.33, P=0.0013) and eating style (with leptinr=0.21, P=0.0423; with insulin r=0.29, P=0.0056) in obese children.The meal size is increased with the appetite class (r=0.25, P=0.017)in obese children, but not in control children. These evidences show thatbig meal size, good appetite and fast eating style may not appear at sametime in children. The appetite of human is influenced by social livingenvironment and is not merely driven by physio-instinct, This could beone of reasons that the effects of leptin on appetite in obese human areother than the results that came from animals' studies.5. A paired design study is carried out on obese children. The serumlevels of adiponectin are significantly lower in obese children than incontrol children (7.60vs. 10.68μg/ml; P=0.0004). Father analysisreveals that the difference of adiponectin levels between obese and normalchildren are more greatly in girls (6.87 vs. 11.62μg/ml; P=0.0002) thanthat of in boys (8.01 vs. 9.23μg/ml; P=0.2414).The sex difference of adiponectin levels do not found in both obese and nonobese children, but the positive correlation between serum levelsof adiponectin and age is found in both obese and nonobese children inthe study. The results also show that plasma adiponectin levels arenegatively correlated with Ggt (r=-0.25, P=0.0494) and fasting seruminsulin (r=-0.31, P=0.0056); as well as apositively correlated withGlu (r=0.23, P=0.0412) and IAI (r=0.25, P=0.0259) in obese children.And more, plasma adiponectin levels are negatively correlated with Glu(r=-0.33, P=0.0036) and positively correlated with Apoal(r=0.32, P=0.0119) and IAI (r=0.22, P=0.0490) in nonobese children.