The effects of a variable ratio (VR) schedule of reinforcement on exercising in obese and non-obese children were examined. Eight 11-year-old boys, four obese and four non-obese, participated as subjects. One obese and one non-obese boy served as a control for social attention and maturation effects. Three obese and three non-obese boys were individually tested five times weekly over approximately 12 weeks on a stationary bicycle. A changing-criterion design was used where 3 VR phases of 8 sessions each were followed by a 3 session mini-reversal phase and a 5 session return-to-third VP phase. Each successive criterion was increased over previous performance by approximately 15%. Implementation of the initial VR subphase produced marked increases in the rate of exercising for all children with continued acceleration until the withdrawal of reinforcement phase when rates decreased. Response rates recovered during the final VP phase where the highest rates were achieved for all subjects. Cumulative records demonstrated high stable responding with no discernible pausing for non-obese boys. In contrast, pausing and accelerating which were initially evident in the obese boys' records were eliminated with higher VR schedules. The anthropometric measures taken at the pre-experimental, post-experimental and follow-up time periods revealed that the obese boys who participated in the program gained substantially less weight than children who did not participate. There appeared to be no systematic difference in self-reported food intake between obese and non-obese children. Actometer data, as well as parents' and teachers' written and verbal reports indicated that exercise on a stationary bicycle, intermittently reinforced, as well as training parents to utilize praise and attention for exercise, appeared to increase physical activity in the natural environment. A social validation questionnaire as well as informal observation revealed that participants, parents, and teachers rated the biking program most positively.

Thesis (MNutr)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Introduction: The worldwide increase in the prevalence of childhood overweight and obesity has been identified as a major threat to children’s health and South Africa has not been spared. A child’s food environment is constrained and shaped by their parents/carers who provide food based on own food preferences and food selections, which in turn are determined by the larger cultural, social and economic context. Risk factors for childhood obesity are not well established. Existing prevention strategies, focusing on late childhood and adolescence, are largely unsuccessful. There is however an increasing body of evidence that the early life environment is an important determinant of risk of obesity in later life. Aim: To determine prevalence and socio-demographic risk factors associated with childhood overweight and obesity in the Stellenbosch area, Western Cape Province. Methods: Cross-sectional, comparison study. A representative group of 638 children (aged 6- 13 years) attending three randomly selected Stellenbosch primary schools were weighed and measured to calculate body mass index (BMI) using international obesity task force (IOTF) guidelines in the screening phase of the project to determine the prevalence of overweight and obesity. The comparison study phase identified 84 overweight and obese children and 84 children of normal weight (comparison group) to comprise a sample population of 168 children. Socio-demographic data were determined with a structured questionnaire and compared between the overweight/obese group and comparison group (normal weight) to identify associated risk factors and investigate the Ho. Results: The prevalence of overweight and obesity in the sample of primary school children was 13% (n=84) as determined by BMI, of which 9% (n=57) were classified as overweight and 4% (n=27) as obese. Socio-economic factors including maternal employment hours (p=0.0462), family characteristics e.g. number of children in the household (p=0.0231), eating behaviour like consuming brown rice (p=0.0371), pork (p=0.0143), canola/olive-based margarine (p=0.0398) or poly-unsaturated margarine (p=0.0481), doughnuts (p=0.0280) and time spent doing sport (p=0.0450) were significantly associated with overweight or obesity. Ho were thus rejected. Conclusion: The results suggest that maternal working hours, the number of children in the household, poor eating habits and time spent doing sport are important predictor variables for childhood overweight and obesity. Socio-economic status, infant feeding practices and family characteristics like marital circumstances, household number, and mother’s age did not appear to play a role in the development of childhood overweight and obesity in this population. In light of this evidence, preventative initiatives should pro-actively promote healthy eating behaviour and physical activity to children at an early age, in particular girls. Involving families and schools in these initiatives is recommended as well as a national childhood obesity monitoring system to identify children at risk and tracking trends of childhood obesity in guiding evidence-based interventions to tackle this major health problem. / AFRIKAANSE OPSOMMING: Inleiding: Die wêreldwye toename in die prevalensie van kinder-oorgewig en vetsugtigheid is geïdentifiseer as 'n groot bedreiging vir kinders se gesondheid en Suid-Afrika word nie gespaar nie. 'n Kind se voedingsomgewing is beperk en word gevorm deur ouers of versorgers wat voedsel voorsien gebaseer op hul eie kos voorkeure en voedsel keuses, wat op sy beurt deur die groter kulturele, sosiale en ekonomiese konteks bepaal word. Risiko faktore vir kinder-vetsugtigheid is nie goed gevestig nie. Bestaande voorkoming strategieë, wat fokus op die laat kinderjare en vroeë adolessensie, is grootliks onsuksesvol. Daar is egter voortdurende toename in bewyse dat die vroeë lewensomgewing ‘n belangrike bepalende risiko faktor is vir vetsugtigheid in latere lewe. Doelstellings: Bepaling van prevalensie en sosio-demografiese risiko faktore wat geassosieer word met kinder-oorgewig en vetsugtigheid in die Stellenbosch area, Wes-Kaap Provinsie. Metodes: Deursnit, vergelykende studie. ‘n Verteenwoordigende groep van 638 kinders (ouderdom 6-13 jaar) skoolgaande by drie ewekansig geselekteerde Stellenbosch primêre skole was geweeg en gemeet om Liggaamsmassa Indeks (LMI), volgens die internasionale obesiteit werkgroep (IOTF) riglyne te bereken in die siftingsfase van die projek ter bepaling van prevalensie van oorgewig en vetsugtigheid. Die vergelykende fase het 84 oorgewig en vetsugtige kinders geidentifiseer en 84 kinders met normale gewig (vergelykende groep) ter samestelling van ‘n steekproef populasie van 168 kinders. Sosio-demografiese data was verkry deur ‘n gestruktureerde vraelys en vergelykings was getref tussen oorgewig/vetsugtige groep en vergelykende groep (normale gewig) ter identifisering van geassosieerde risiko faktore en ondersoek van die Ho. Resultate: Prevalensie van oorgewig en vetsugtigheid in die steekproef van primêre skool kinders was 13%(n=84) waarvan 9%(n=57) geklassifiseer was as oorgewig en 4%(n=27) as vetsugtig. Sosio-ekonomiese faktore soos moeders se werksure (p=0.0462), familie kenmerke soos aantal kinders in ‘n huishouding (p=0.0231), eetgedrag nl. bruin rys (p=0.0371), varkvleis (p=0.0143), canola/olyf-gebaseerde margarien (p=0.0398) of polionversadigde margarien (p=0.0481), oliebolle (p=0.0280) en tyd gespandeer aan sport (p=0.0450) was beduidend geassosieer met oorgewig en obesiteit. Ho was dus verwerp. Gevolgtrekking: Die resultate dui daarop dat moeders se werksure, aantal kinders in ‘n huishouding, swak eetgewoontes en tyd gespandeer aan sport, belangrike voorspellers vir kinder-oorgewig en vetsugtigheid is. Sosio-ekonomiese status, baba-voedingspraktyke en familie kenmerke soos huwelikstatus, huishoudelike getal en moeders se ouderdom blyk nie ‘n rol te speel in die ontwikkeling van kinder-oorgewig en obesiteit in hierdie populasie nie. Na aanleiding van hierdie bevindinge moet voorkoming inisiatiewe pro-aktief gesonde eetgewoontes en fisiese aktiwiteit in kinders aanmoedig reeds op 'n vroeë ouderdom, veral in meisies. Die betrekking van gesinne en skole in hierdie inisiatiewe word aanbeveel asook 'n nasionale kinder vetsugtigheids-moniteringstelsel om risiko kinders te identifiseer en die tendense van kinder-vetsugtigheid te volg in die begeleiding van navorsings-gebaseerde intervensies om hierdie belangrike gesondheidsprobleem aan te spreek.

No description available.

Objectives: This study examined the relation of multiple aspects of the home food environment to dietary intake and body weight among overweight and obese children in southern Appalachia. Methods: The study used baseline data from a cluster-randomized controlled trial, Parent-Led Activity and Nutrition for Healthy Living, evaluating a parent-mediated approach to treating child overweight and obesity in the primary care setting in southern Appalachia. Sixty-seven children ages 5 to 11 years were recruited from four primary care clinics. Multiple linear regression was used to estimate the relation between multiple aspects of the home food environment to dietary intake (fruit and vegetable intake, fat and sweets intake), and standardized body mass index (zBMI), adjusted for baseline family characteristics (education, smoking status during the past month, BMI) and child characteristics (sex, age, Medicaid/TennCare). Results: Findings showed greater parental restriction and pressure in feeding were associated with greater fruit and vegetable intake in children (β = 0.33, β = 0.30, respectively; both P < 0.05). The availability of chips and sweets in a child’s home and parental inappropriate modeling of eating were associated with an increased risk for consumption of fats and sweets by children (β = 0.47, β = 0.54, respectively; both P < 0.01). Parental monitoring of the child’s eating was associated with a reduced risk for fat and sweets intake (β = −0.24; P < 0.01). Finally, parental responsibility for feeding the child was associated with lower zBMI (β = −0.20; P < 0.05). Conclusions: The home food environment, including food availability and parenting behaviors, was associated with overweight and obese children’s dietary intake and weight. This study adds to evidence suggesting that programs aimed at improving overweight and obese children’s eating patterns may target both aspects of the physical home environment and parental behaviors surrounding eating.

The prevalence of insulin resistance and type 2 diabetes mellitus (T2DM) in obese children and adolescents is growing at an alarming rate, especially in ethnic minorities. It is not clear whether young people of different ethnic backgrounds vary in their metabolic response to excessive adiposity. Differences in lipid partitioning in the abdominal fat compartments have been observed among different ethnic groups. The aim of this study was to evaluate whether there are ethnic differences in intramyocellular lipid (IMCL) levels that are related to differences in insulin sensitivity. Eighty-two obese children and adolescents underwent 1) 1H nuclear magnetic resonance (NMR) spectroscopy to non-invasively quantify IMCL levels in their soleus muscle, 2) an oral glucose tolerance test and (in a subset of subjects) a euglycemic-hyperinsulinemic clamp to assess insulin sensitivity, 3) a dual-energy X-ray absorptiometry (DEXA) scan to measure total percent body fat, and 4) magnetic resonance imaging to measure abdominal fat distribution. IMCL levels in Hispanic children and adolescents (1.50 ± 0.64%) were significantly greater than in their Caucasian (1.19 ± 0.40%) and African-American (1.09 ± 0.49%) peers. Visceral fat was significantly lower in African Americans (42.7 ± 18.8cm2) and were similar in Caucasians (70.9 ± 27.5cm2) and Hispanics (77.3 ± 41.9cm2). The three groups were not different with respect to insulin sensitivity. For the entire cohort, IMCL levels were inversely related to insulin sensitivity. There was a significant correlation between visceral fat and insulin resistance in Hispanics and Caucasians but not in African Americans. In conclusion, these data suggest that there are significant ethnic differences in lipid partitioning in both the muscle and abdominal compartment. These findings may explain ethnic differences in insulin sensitivity and further the understanding of the pathogenesis of insulin resistance and T2DM.

A obesidade, ou o corpo obeso, é uma condição que vem atingindo a adultos e a crianças, análises sobre esta realidade merecem ser investigadas na perspectiva das emoções. Sabe-se que a alimentação é um fenômeno complexo, possuindo múltiplos determinantes. Com relação ao fator psicológico, sabe-se que suas bases estão relacionadas à figura materna e que alterações no desenvolvimento da criança relacionadas a esta são um dos fatores etiológicos de problemas alimentares, como o da obesidade. Este estudo teve como objetivo compreender as vivências relacionadas à alimentação de mães de filhos obesos com as suas próprias mães e a forma como esta relação pode influenciar no cuidado com a alimentação de seus filhos. A abordagem é qualitativa, utilizando a entrevista compreensiva como abordagem empírica. Foram entrevistadas doze mães, com filhos crianças ou adolescentes que tiverem o diagnóstico de obesidade. Observou-se que a alimentação, dentro do contexto de vida contemporâneo, traz o paradoxo do excesso de objetos disponíveis ao consumo, de novos produtos a todo tempo no mercado, acompanhado de relações vazias e da falta de laços. A obesidade traz a questão do vazio e do alimento como um objeto preenchedor do mesmo. A pesquisa em questão apontou para a existência de processos identitários entre mães e filhos, havendo questões mal resolvidas das mães projetadas em suas relações com seus filhos com obesidade, mediadas pelo ato de alimentar. Outros fatores como crenças sócio- culturais e relacionadas ao gênero também estariam exercendo influência sobre os comportamentos maternos frente a alimentação de seus filhos. / The obesity, or the obese body, is a condition that is affecting adults and children, analysis of this reality deserve to be investigated from the emotions perspective. Its known that feeding is a complex phenomenon, with multiple determinants. About the psychological factors, its known that theyre linked to the maternal figure and changes in the children development related to this are one of the etiological factors of eating problems such as obesity. This study aimed to understand the mothers of obese children feeding experiences, with their own mothers, and how this relationship can influence the feeding care with their children. The research is qualitative, using the comprehensive interview as empirical approach. Twelve mothers of children or teenagers, diagnosed with obesity, were interviewed. It was observed that food, at the context of contemporary life, brings the paradox of the excess objects available for consumption, new products all the time on the market, accompanied by shallow relationships and lack of ties. Obesity raises the question of emptiness and food as a filler object. This research pointed to the existence of identity processes between mothers and obese children, involving unresolved mothers issues projected in their relationships with their children, mediated by the feeding practice. Other factors such as socio-cultural and gender beliefs were also influencing maternal feeding behaviors with their children.

A obesidade, ou o corpo obeso, é uma condição que vem atingindo a adultos e a crianças, análises sobre esta realidade merecem ser investigadas na perspectiva das emoções. Sabe-se que a alimentação é um fenômeno complexo, possuindo múltiplos determinantes. Com relação ao fator psicológico, sabe-se que suas bases estão relacionadas à figura materna e que alterações no desenvolvimento da criança relacionadas a esta são um dos fatores etiológicos de problemas alimentares, como o da obesidade. Este estudo teve como objetivo compreender as vivências relacionadas à alimentação de mães de filhos obesos com as suas próprias mães e a forma como esta relação pode influenciar no cuidado com a alimentação de seus filhos. A abordagem é qualitativa, utilizando a entrevista compreensiva como abordagem empírica. Foram entrevistadas doze mães, com filhos crianças ou adolescentes que tiverem o diagnóstico de obesidade. Observou-se que a alimentação, dentro do contexto de vida contemporâneo, traz o paradoxo do excesso de objetos disponíveis ao consumo, de novos produtos a todo tempo no mercado, acompanhado de relações vazias e da falta de laços. A obesidade traz a questão do vazio e do alimento como um objeto preenchedor do mesmo. A pesquisa em questão apontou para a existência de processos identitários entre mães e filhos, havendo questões mal resolvidas das mães projetadas em suas relações com seus filhos com obesidade, mediadas pelo ato de alimentar. Outros fatores como crenças sócio- culturais e relacionadas ao gênero também estariam exercendo influência sobre os comportamentos maternos frente a alimentação de seus filhos. / The obesity, or the obese body, is a condition that is affecting adults and children, analysis of this reality deserve to be investigated from the emotions perspective. Its known that feeding is a complex phenomenon, with multiple determinants. About the psychological factors, its known that theyre linked to the maternal figure and changes in the children development related to this are one of the etiological factors of eating problems such as obesity. This study aimed to understand the mothers of obese children feeding experiences, with their own mothers, and how this relationship can influence the feeding care with their children. The research is qualitative, using the comprehensive interview as empirical approach. Twelve mothers of children or teenagers, diagnosed with obesity, were interviewed. It was observed that food, at the context of contemporary life, brings the paradox of the excess objects available for consumption, new products all the time on the market, accompanied by shallow relationships and lack of ties. Obesity raises the question of emptiness and food as a filler object. This research pointed to the existence of identity processes between mothers and obese children, involving unresolved mothers issues projected in their relationships with their children, mediated by the feeding practice. Other factors such as socio-cultural and gender beliefs were also influencing maternal feeding behaviors with their children.

Introdução: A obesidade é uma doença crônica que aumenta sua prevalência progressivamente no mundo todo. Uma das suas principais complicações é a doença hepática gordurosa não alcoólica (DHGNA), que pode apresentar-se de forma assintomática, com esteatose hepática, esteato-hepatite, cirrose e hepatocarcinoma. Está associada à dislipidemia, hipertensão, diabetes, síndrome metabólica e resistência insulínica. O padrão ouro para seu diagnóstico é a biopsia hepática, considerado método invasivo. Medidas indiretas são usadas para auxiliar na sua detecção, como dados do exame físico, exames de bioquímica e de imagem. Objetivo: Diagnosticar DHGNA usando a ressonância nuclear magnética (RNM) como método não invasivo, correlacionando-a com achados clínicos e laboratoriais. Metodologia: Estudo transversal de 50 crianças e adolescentes seguidas no Ambulatório de Obesidade do Hospital das Clínicas da FMRP-USP. Foram submetidas à questionário sobre histórico pessoal e familiar, à exame físico, exames laboratoriais (lipidograma, transaminases, glicemia e insulina basal) e RNM de abdome para cálculo da de gordura hepática, visceral e subcutânea. Resultados: Diagnosticado esteatose hepática em 14 (28%) dos participantes, sendo 8 com esteatose grave (porcentagem de gordura >18%) e 4 não grave (porcentagem gordura hepática entre 9 e 18%). Houve diferença estatisticamente significante entre a gordura hepática detectada pela RNM e o gênero masculino, triglicérides, TGO, TGP, relação TGO/TGP e acantose nigricans. O cálculo do Homeostasis Model Assessment Insulin Resistance (HOMA-IR) e da síndrome metabólica não apresentaram relação positiva com a porcentagem de gordura hepática. Conclusão: A frequência de esteatose hepática, utilizando a RNM como ferramenta diagnóstica, foi inferior à encontrada na literatura. Dos parâmetros estudados, os melhores preditores de esteatose hepática foram triglicérides, TGO, TGP, relação TGO/TGP, gênero masculino, acantose nigricans e Z escore para IMC elevado / Introduction: Obesity is a chronic disease whose prevalence progressively increasing worldwide. One of its main complications is non-alcoholic fatty liver disease (NAFLD), which may occur in an asymptomatic form, as simple fatty liver, steatohepatites (NASH), cirrhosis and hepatocellular carcinoma. This disease is associated with dyslipidemia, hypertension, diabetes, metabolic syndrome and insulin resistance. The gold standard for diagnosis is a liver biopsy, considered to be an invasive method. Indirect measures are used to aid its diagnosis, such as physical, biochemical and imaging tests. Objective: Diagnosing NAFLD using MRI as non-invasive method and correlating it with clinical and laboratory findings. Methodology: A cross-sectional study of 50 children and adolescents followed at the Obesity clinic of the University Hospital, FMRP-USP. A questionnaire about personal and family history was aplplied and each subject was submitted to physical examination, laboratory tests (lipip profile, transaminases, glycemia and basal insulin) and magnetic resonance imaging (MRI) of the abdomen for calculation of hepatic, visceral and subcutaneous fat. Results: Fatty liver disease was diagnosed in 14 (28%) of the participants, 8 of them with severe steatosis (fat percentage > 18%) and 4 with milder steatosis (fat percentage between 9 and 18%). There was a statistically significant difference between the hepatic fat detected by MRI and male gender, triglycerides, AST, ALT, AST/ALT ratio and acanthosis nigricans. The calculation of the Homeostasis Model Assessment Insulin Resistance (HOMA-IR) and of the metabolic syndrome did not show a positive relationship with the percentage of hepatic fat. Conclusion: The frequency of hepatic steatosis using MRI as a diagnostic tool, was lower than the values reported in the literature. Among the parameters studied, the best predictors of liver steatosis were triglycerides, AST, ALT, AST/ALT ratio, male gender, acanthosis nigricans and Z score for high body mass index

Introdução: A obesidade é uma doença crônica que aumenta sua prevalência progressivamente no mundo todo. Uma das suas principais complicações é a doença hepática gordurosa não alcoólica (DHGNA), que pode apresentar-se de forma assintomática, com esteatose hepática, esteato-hepatite, cirrose e hepatocarcinoma. Está associada à dislipidemia, hipertensão, diabetes, síndrome metabólica e resistência insulínica. O padrão ouro para seu diagnóstico é a biopsia hepática, considerado método invasivo. Medidas indiretas são usadas para auxiliar na sua detecção, como dados do exame físico, exames de bioquímica e de imagem. Objetivo: Diagnosticar DHGNA usando a ressonância nuclear magnética (RNM) como método não invasivo, correlacionando-a com achados clínicos e laboratoriais. Metodologia: Estudo transversal de 50 crianças e adolescentes seguidas no Ambulatório de Obesidade do Hospital das Clínicas da FMRP-USP. Foram submetidas à questionário sobre histórico pessoal e familiar, à exame físico, exames laboratoriais (lipidograma, transaminases, glicemia e insulina basal) e RNM de abdome para cálculo da de gordura hepática, visceral e subcutânea. Resultados: Diagnosticado esteatose hepática em 14 (28%) dos participantes, sendo 8 com esteatose grave (porcentagem de gordura >18%) e 4 não grave (porcentagem gordura hepática entre 9 e 18%). Houve diferença estatisticamente significante entre a gordura hepática detectada pela RNM e o gênero masculino, triglicérides, TGO, TGP, relação TGO/TGP e acantose nigricans. O cálculo do Homeostasis Model Assessment Insulin Resistance (HOMA-IR) e da síndrome metabólica não apresentaram relação positiva com a porcentagem de gordura hepática. Conclusão: A frequência de esteatose hepática, utilizando a RNM como ferramenta diagnóstica, foi inferior à encontrada na literatura. Dos parâmetros estudados, os melhores preditores de esteatose hepática foram triglicérides, TGO, TGP, relação TGO/TGP, gênero masculino, acantose nigricans e Z escore para IMC elevado / Introduction: Obesity is a chronic disease whose prevalence progressively increasing worldwide. One of its main complications is non-alcoholic fatty liver disease (NAFLD), which may occur in an asymptomatic form, as simple fatty liver, steatohepatites (NASH), cirrhosis and hepatocellular carcinoma. This disease is associated with dyslipidemia, hypertension, diabetes, metabolic syndrome and insulin resistance. The gold standard for diagnosis is a liver biopsy, considered to be an invasive method. Indirect measures are used to aid its diagnosis, such as physical, biochemical and imaging tests. Objective: Diagnosing NAFLD using MRI as non-invasive method and correlating it with clinical and laboratory findings. Methodology: A cross-sectional study of 50 children and adolescents followed at the Obesity clinic of the University Hospital, FMRP-USP. A questionnaire about personal and family history was aplplied and each subject was submitted to physical examination, laboratory tests (lipip profile, transaminases, glycemia and basal insulin) and magnetic resonance imaging (MRI) of the abdomen for calculation of hepatic, visceral and subcutaneous fat. Results: Fatty liver disease was diagnosed in 14 (28%) of the participants, 8 of them with severe steatosis (fat percentage > 18%) and 4 with milder steatosis (fat percentage between 9 and 18%). There was a statistically significant difference between the hepatic fat detected by MRI and male gender, triglycerides, AST, ALT, AST/ALT ratio and acanthosis nigricans. The calculation of the Homeostasis Model Assessment Insulin Resistance (HOMA-IR) and of the metabolic syndrome did not show a positive relationship with the percentage of hepatic fat. Conclusion: The frequency of hepatic steatosis using MRI as a diagnostic tool, was lower than the values reported in the literature. Among the parameters studied, the best predictors of liver steatosis were triglycerides, AST, ALT, AST/ALT ratio, male gender, acanthosis nigricans and Z score for high body mass index