Abstract Background There is a great need for improved dietary assessment methods that give valid intake data and are more user friendly than traditional methods. Objectives The aim of this thesis was to develop, implement, and evaluate dietary assessment methods using new approaches and technologies in young populations, and to investigate variables that are important for reporting accuracy. Another aim was to investigate day-of-the-week effects on assessed energy and sugar intakes among children and adolescents. Methods This thesis is based on data collected as part of four different studies on the implementation of the following dietary assessment methods: the short dietary questionnaire (SDQ), a food record (FR) with either a digital camera or smartphone, and a computer-based 24-hour recall. Young pregnant and non-pregnant women with different weight statuses completed the SDQ. Children with overweight and obesity used digital cameras to complete FRs, and adolescents used the smartphone application FR. Parents of 2‒9-year-old European children completed the computer-based 24-hour recall and the results of sugar intake of the children on weekdays and weekends were analysed. The SDQ was evaluated against doubly labelled water (DLW) and a more extensive food frequency questionnaire (FFQ). The two FRs were evaluated against data from a SenseWear Armband (SWA), and the smartphone FR was further compared to a web-based FR. Results The new approaches and technologies used in the dietary assessment methods in this thesis captured between 70% and 79% of the energy intake (EI) of children, adolescents and young women, and the ranking according to EI was generally low with all methods. The negative effect on reporting accuracy with increasing BMI/weight status that has been observed previously was confirmed in our studies. In children and adolescents, a weekend day in the FR emerged as a factor that was positively associated with reporting accuracy. Assessed sugar intake in children and adolescents was high in general and highest on weekends, although EI did not differ between weekdays and weekends. Conclusions FRs using technology should focus on simplifying the recording of consumed foods and amounts to a greater extent, for example, by automatizing these steps as much as possible. The SDQ could be further adapted for testing among other groups than young women, and could be adapted for specific objectives. Factors influencing reporting accuracy need to be taken into consideration and further explored when assessing dietary intake. In order to make it possible to evaluate sugar intake in relation to nutritional recommendations, information about added sugar in foods needs to be incorporated into food composition databases. Further development and research is needed to obtain dietary assessment methods with improved accuracy and user friendliness. / Sammanfattning Bakgrund Traditionella kostundersökningsmetoder är krävande och har flera felkällor, vilket ofta leder till att energiintaget (EI) från insamlade kostdata är lägre än individens uppmätta totala energiförbrukning (TEE). Det finns ett stort behov av kostundersökningsmetoder som ger valida resultat och är användarvänliga. Syfte Syftet med avhandlingen var att vidareutveckla kostundersökningsmetoder och att im plementera och utvärdera dem bland barn, ungdomar och unga kvinnor. Syftet var också att undersöka faktorer med betydelse för en korrekt rapportering av kostintaget. Vidare var syftet att undersöka skillnader i EI och intag av socker under vardagar och helger bland barn och ungdomar. Metod Avhandlingen baseras på data från fyra olika studier där olika nyutvecklade kostundersökningsmetoder användes. I en studie användes en kort kostenkät (SDQ) på unga gravida och icke-gravida kvinnor med olika viktstatus. Rapporterat EI jämförde s med TEE uppmätt med dubbelmärkt vatten-metoden, och rapporterat intag av näringsämnen och livsmedel jämfördes med en mer omfattande kostenkät (FFQ). I en annan studie samlades kostdata in för 2 ‒ 9-åringar från åtta europeiska länder med hjälp av en datoriserad 24-timmars recall som besvarades av föräldrarna. Barnens socker- och energiintag jämfördes mellan måndag ‒ torsdag, fredag och helg. I en tredje studie genomförde 8 ‒ 12-åringar med övervikt eller fetma en kostregistrering med hjälp av digitalkamera vid upprepade tillfällen. I en fjärde studie utvecklades och anvä ndes en smartphoneapplikation för kostregistrering bland 15-åringar, som också använde en webb-baserad kostregistrering. Rapporterat EI med kostregistreringarna utvärderades i jämförelse med TEE mätt med SenseWear Armband, och EI och sockerintag under vardagar och helger undersöktes. Resultat SDQ underskattade EI med 30 % bland de icke-gravida kvinnorna och en signifikant högre underskattning skedde bland kvinnorna med övervikt eller fetma. SDQ underskattade EI med 21 % bland de gravida kvinnorna. SDQ kunde dock rangordna EI bland kvinnorna med övervikt eller fetma och gav ett högre estimerat intag av flera näringsämnen och de flesta livsmedel jämfört med FFQ bland de icke-gravida kvinnorna. De nyutvecklade kostregistreringsmetoderna underskattade EI bland barn med 24 % och bland ungdomar med 29 %. Digitalkamerametoden visade god reproducerbarhet för de olika mättillfällena bland barn. Smartphoneapplikationen kunde uppskatta ungdomars TEE och pojkars fysiska aktivitetsnivå med en fråga om den dagliga fysiska aktiviteten. Underskattning av EI ökade med BMI och var lägre när en helgdag fanns med i kostregistreringen för både barn och ungdomar. Bland barnen iv underskattades EI mer bland flickor än pojkar och underskattningen ökade med åldern. Det fanns ingen signifikant skillnad i intagsmängd av näringsämnen och livsmedel när de mättes med smartphoneapplikationen jämfört med den webb-baserade kostregistreringen, och flera näringsämnen och livsmedel var signifikant korrelerade mellan de båda metoderna. EI hos barn i Europa skilde sig inte åt mellan vardagar och helger, men det totala intaget av mono- och disackarider och/eller livsmedel med hög andel tillsatt socker eller sackaros var generellt högre på helgerna. Sockerintaget på fredagar var ett mellanting mellan intaget under vardagar och helger hos de europeiska barnen. Konklusion De nyutvecklade kostundersökningsmetoderna fångade i genomsnitt mellan 70 % och 79 % av EI bland barn, ungdomar och unga kvinnor, och förmågan att rangordna EI var generellt låg med metoderna. Liksom i tidigare studier underskattades EI i högre grad hos de med övervikt/fetma eller högre BMI i alla grupperna, och bland barn och ungdomar framkom att validiteten ökade med en helgdag i kostregistreringen som en ny påverkande faktor. Barns och ungdomars sockerintag var generellt högt och som högst under helgen. Det finns ett stort behov av fortsatt forskning för att förbättra kostundersökningsmetoders validitet och användarvänlighet. För kostregistreringsmetoder som använder sig av teknik bör fokus i vidareutvecklingen vara på att göra det enklare för användaren att registrera konsumerade livsmedel och portionsstorlekar, till exempel genom att automatisera dessa steg i så hög grad som möjligt. SDQ kan anpassas och utvärderas även i andra grupper och för olika syften. Faktorer med betydelse för en korrekt rapportering av kost intaget bör tas i beaktande även fortsättningsvis samt undersökas vidare. För att göra det möjligt att utvärdera intaget av socker i jämförelse med näringsrekommendationer bör information om mängden tillsatt socker i livsmedel inkluderas i livsmedelsdatabaser.

Abstract The aim of the study was to describe how school nurses experience the work with overweightchildren and youths from the compulsory school to upper secondary school and what kind ofnursing interventions they perform. The study had a descriptive design and ten school nursesfrom a municipality in the middle of Sweden participated. Data were collected by semistructured interviews and analyzed using qualitative content analysis. The result is presentedin six categories and one theme. The category to identify and investigate describes how theschool nurses, based on the result from the health interviewing, identified and investigated theoverweight children. To offer and follow up describes how the school nurses experienced theextensive program. To motivate describes the school nurses difficulties in motivating, theirexperiences of benefits when using the method “motivational interviewing”, their thoughtsabout choosing the right words and the importance in involving the parents. To experiencegood results describes what the school nurses considered important by the childrenthemselves to do, in order to achieve a good result. To experience difficulties describes whichdifficulties the school nurses feel they face in the work with overweight children. Wanting tochange describes which changes the school nurses wanted to have regarding the care ofoverweight children. The theme “a bit on the way but not quite there” emerges from thecategories and describes how the school nurses experience the work with overweight children and youths. Keywords: school nurse, overweight, children, experiences / Sammanfattning Syftet med studien var att belysa hur skolsköterskor upplever arbetet med överviktiga barnoch ungdomar från grundskolan upp till och med gymnasiet samt vilka omvårdnadsåtgärderde utför. Studien hade en beskrivande design och tio skolsköterskor från en kommun iMellansverige deltog i studien. Data samlades in via semistrukturerade intervjuer ochanalyserades utifrån kvalitativ innehållsanalys. Resultatet redovisas i sex kategorier och etttema. Kategorin att identifiera och utreda beskriver hur skolsköterskorna med hjälp avhälsosamtalet identifierade och därefter utredde överviktiga barn. Att erbjuda och följa uppbeskriver hur skolsköterskorna upplevde det utvidgade överviktsprogrammet. Att motiverabeskriver svårigheter som skolsköterskorna upplevde i att motivera, deras upplevelser avfördelar med metoden ”motiverande samtal”, deras tankar om vikten av att välja rätt ord isamtalet samt betydelsen av att involvera föräldrarna. Att uppleva bra resultat beskriver vadskolsköterskorna ansåg krävdes av barnen för att uppnå ett bra resultat. Att upplevasvårigheter beskriver vilka svårigheter skolsköterskorna ansåg att de möter i arbetet medöverviktiga barn. Slutligen att vilja förändra beskriver vilka förändringar skolsköterskornaville göra när det gällde omhändertagandet av överviktiga barn. Temat ”en bit på väg men inteända fram” framkom ur kategorierna och beskriver hur skolsköterskorna upplevde arbetetmed överviktiga barn och ungdomar. Nyckelord: skolsköterska, övervikt, barn, upplevelser

Bakgrund: Sett över världen har förekomsten av fetma nästintill fördubblats sedan 1980-talet. Runt om i världen dör årligen 3,4 miljoner vuxna människor till följd av övervikt och fetma. Utöver det dör människor av diabetes, hjärt- kärlsjukdomar och cancer som många gånger kan kopplas till deras kroppsvikt. Syfte: Syftet är att beskriva hur vuxna med övervikt och fetma upplever sin hälsa. Metod: En litteraturöversikt av 12 vetenskapliga artiklar med kvalitativ metod. Resultat: Övervikt och fetma påverkar hälsan vilket innefattar det fysiska, psykiska och sociala välbefinnandet. Personer med övervikt och fetma isolerar sig, känner skuld och skam samtidigt som de undviker fysiska gruppaktiviteter eftersom de oroar sig för medmänniskors blickar och kommentarer. Personer upplever att deras hälsa påverkas negativt och att de hämmas i sin vardag. Slutsatser: Om sjuksköterskan har en ökad förståelse för hur personer med övervikt och fetma upplever sin hälsa, kan det bidra till att det blir enklare för sjuksköterskan att bemöta personerna. Övervikt och fetma är ett växande hälsoproblem därför behövs vidare forskning inom ämnet. / Background: Seen over the world the occurrence of obesity has doubled since the 1980s. All around the world 3,4 million adults die each year in consequence of overweight and obesity.  Additionally there are people who die because of diabetes, cardiovascular diseases and cancer, which are many times connected with their body weight. Purpose: The purpose is to describe how adults with overweight and obesity experience their health. Method: A literature review of 12 scientific articles with a qualitative method. Results: Overweight and obesity affects the health including the physical, psychological and social wellbeing. People with overweight and obesity isolate themselves, feel guilt and shame in the same time as they avoid physical activities because they are concerned about how people will look at them or what they will say. People experience that it has a negative impact on their health and that it diminishes them in their everyday life. Conclusion: If nurses have an increased understanding for how people with overweight and obesity experience their health, it could contribute to a better and easier approach from the nurse to these people. Overweight and obesity is a growing health issue, which needs further research.

Darbo tikslas. Įvertinti gyvensenos ir genetinių veiksnių sąsajas su dvynių antropometriniais rodikliais. Uždaviniai. 1. Nustatyti monozigotinių ir dizigotinių dvynių antropometrinius rodiklius; 2. Įvertinti antropometrinių rodiklių ir gyvensenos sąsajas su genetiniais veiksniais; 3. Nustatyti normalaus svorio ir antsvorio turinčių dvynių gyvensenos skirtumus; 4. Nustatyti gyvensenos veiksnių ryšį su antropometriniais rodikliais, atsižvelgiant į genetinius veiksnius. Tyrimo metodika. Tirti Lietuvoje gyvenantys 18–54 metų dvyniai, kurie yra įtraukti į Dvynių centro registrą ir kurių buvo žinomas elektroninio pašto adresas. Vykdyta apklausa paštu. Anketą sudarė 51 klausimas apie dvynių socialinius rodiklius, sveikatos būklę, jų ūgį ir svorį bei gyvensenos įpročius. Anketos buvo išsiųstos 146 dvynių poroms. Jas grąžino 159 asmenys (atsako dažnis 54,5 proc.). Analizuoti 70 (40 monozigotinių ir 30 dizigotinių) dvynių porų duomenys. Antsvorio paplitimas skaičiuotas pagal kūno masės indeksą (KMI>25 kg/m2). Rezultatai. Antsvorio paplitimas tarp vyrų buvo 31,3 proc., tarp moterų – 19,4 proc. Jis dažniau nustatytas 35 metų ir vyresniems bei turintiems kolegijos išsilavinimą dvyniams. Nustatyti stiprūs ryšiai tarp visų MZ dvynių porų antropometrinių rodiklių. Labiausiai susijęs buvo monozigotinių dvynių ūgis (koreliacijos koeficientas – 0,941). Monozigotiniai dvyniai dažniau turėjo vienodus fizinio aktyvumo, mitybos ir žalingus įpročius nei dizigotiniai. Antsvorio paplitimas buvo... [toliau žr. visą tekstą] / Aim of the study. To evaluate the associations of behavioural and genetic factors with anthropometrical measurements of twins. Objectives. 1. To assess the antropometric indicators of monozigotic and dizigotic twins; 2. To evaluate the relationship between genetical factors and anthropometric indicators; 3. To identify the differences in health behaviour of twins with normal weight and overweight; 4. To evaluate the aoosiations the behavioural factors with antropometric indicators, taking into account genetic factors. Methods. Study population was 18–54 years old twins living in Lithuania, which were registered in the Twin Center and have e-mail addresses. For this study, the original questionnaire was developed which included 51 questions on sociodemographic characteristics, health status, weight and height, and behavioural habits of twins. The questionnaires were sent by email to 146 twin pairs; 159 individuals returned the filled in questionnaires (response rate 54.5%). The data of 70 twin pairs (40 monozigotic ir 30 dizigotic) were analyzed. Overweight was defined when body mass index (BMI) was >25 kg/m2. The statistical analysis was performed using SPSS 13.0 software package for Windows Results. 31,3 percent of men and 19,4 percent of women had overweight. It is more common for twins over 35 years old, with college degree. A strong correlation among all monozigotic twin couples was found. The height of monozigotic twins was found to be the most related (correlation... [to full text]

Visame pasaulyje grėsmingai auga turinčių antsvorio ir nutukusių vaikų skaičius. Nustatyta, kad vienas iš penkių vaikų Europoje turi antsvorio. Vaikų antsvorio ir nutukimo priežastys įvairios. Tai gali būti susiję su mitybos ir fizinio aktyvumo įpročių pokyčiais, taip pat su ekonominės, socialinės aplinkos įtaka gyvensenai. Vaikų fizinio išsivystymo tyrimai yra vieni svarbiausių stebint jų sveikatos būklę ir augimą. Disertacinis darbas atliktas dalyvaujant tarptautiniame PSO Europos vaikų nutukimo stebėsenos iniciatyvos projekte (COSI), kurio tikslas – rutiniškai stebėti pradinių klasių mokinių (6–9 m.) antsvorio ir nutukimo tendencijas bei sukurti standartizuotą ir Europos mastu suderintą stebėsenos sistemą. / The prevalence of overweight and obesity is growing all over the world and is evaluated as an epidemic. One of five kids in Europe is overweight. The reasons for childhood obesity are of various origins. It might be related to dietary habits and changes in physical activity. The prevalence of obesity also depends on social and economical inequalities. The survey was performed as a part of WHO European Childhood Obesity Surveillance Initiative (COSI). This initiative aimed to measure routinely trends in overweight and obesity in primary school children (6-9 yr.), and to harmonize the collection of anthropometric data across Europe among primary school aged children, based on a common protocol and measurement procedures.

Darbo tikslas įvertinti racionų su skirtingu baltymų kiekiu poveikį nutrijų augimo ir vystimosi bei sveikatingumo rodikliams; įvertinti nutrijų mėsos maistinės ir energinės vertės pokyčius priklausomai nuo raciono baltymingumo. Darbo uždaviniai: 1. pateikti racionų su skirtingu baltymų kiekiu maistinę ir energinę vertę; 2. sekti nutrijų svorio kitimą atskirais auginimo periodais; 3. paskaičiuoti paros priesvorius atskiruose augimo perioduose ir per visą laikotarpį; 4. nustatyti kraujo biocheminius rodiklius; 5. pateikti nutrijų mėsos energinės ir maistinės vertės rodiklius. Naujumas mūsų šalyje pirmą kartą atliktas mokslinis tiriamasis bandymas su nutrijomis, jų šėrimui panaudojant skirtingus baltymų kiekio atžvilgiu racionus. Pirmą kartą pateikiami darbe išanalizuoti duomenys apie nutrijų augimo spartą, sveikatos būklę, sprendžiant iš atliktų kraujo tyrimų, o taip pat pateikta šių švelniakailių žvėrelių dietinės mėsos energinė ir maistinė vertė. Išanalizavus tyrimų rezultatus, atlikus kai kuriuos pastebėjimus, galime pateikti sekančias išvadas: 1. Nutrijų racionuose maisto medžiagų: baltymų : riebalų : angliavandenių santykis: I tiriamosios grupės 21,6 : 2,9 : 57,0; II tiriamosios 25,2 : 3,1 : 53,8, III tiriamosios 28,8 : 3,5 : 49,6; nutrijos buvo šeriamos racionais, kurių sudėtyje buvo 21, 25 ir 29 proc. baltymų; 2. Patinėlių kūno masė 8 mėn. amžiuje buvo 5,83 5,58 6,10 kg, patelių 4,46 4,98 5,20 kg; 3. Intensyviausias kūno masės priaugimas patinėlių buvo 3... [toliau žr. visą tekstą] / Wild animal breeding is a branch of economy that has existed for a long time, therefore, it is necessary for the global economy. Wild animal farming is necessary, because it not only produces exceptionally natural products, but also enables to ecologically utilize the waste produced by the food industry. In Lithuania, the wild animal breeding farms use about 30 thousand tons of the waste of animal origin. The furs of 40-50 million of furry animals are produced each year. At present, the biggest fur industry companies keep up to 30 thousand females, and medium farms keep about 10-20 thousand females. Lithuania is the only country in Eastern Europe where small, family-owned wild animal breeding farms are established, as such farms have been only in Poland for many years. Furry animal breeding business is the branch of agriculture that is most subject to the economic and political processes going on in the world. At present, there are about 20 large wild animal breeding farms in Lithuania. On the other hand, individual breeders are also more and more involved in the wild life breeding industry. The animal breeding business in Lithuania started more than 50 years ago. In the European Union, there are no restrictions for this kind of business, except for environment protection ones. Many nutrias are bred in the United States of America. They were brought to the state of California in 1899 for the first time. 20 nutrias were brought to the state of Louisiana in 1938, and in 1962... [to full text]

Background: Obesity and physical inactivity rates have reached epidemic levels in Canada, but differ based on whether they are self-reported or directly measured. Canadian research examining the combined and independent effects of social and built environments on adult physical activity (PA) and body mass index (BMI) is limited. Furthermore there is a lack of Canadian studies to assess these relationships using directly measured PA and BMI. Objectives: The objectives of this thesis were to systematically compare self-reported and directly measured PA and to examine associations between neighbourhood built and social environmental factors with both self-reported and directly measured PA and overweight/obesity in adults living in Ottawa, Canada. Methods: A systematic review was conducted to identify observational and experimental studies of adult populations that used both self-report and direct measures of PA and to assess the agreement between the measures. Associations between objectively measured neighbourhood-level built recreation and social environmental factors and self-reported individual-level data including total and leisure-time PA (LTPA) and overweight/obesity were examined in the adult population of Ottawa, Canada using multilevel models. Neighbourhood differences in directly measured BMI and PA (using accelerometry) were evaluated in a convenience sample of adults from four City of Ottawa neighbourhoods with contrasting socioeconomic (SES) and built recreation (REC) environments. Results: Results from the review generally indicate a poor level of agreement between self-report and direct measures of PA, with trends differing based on the measures of PA, the level of PA examined and the sex of the participants. Results of the multilevel analyses identified that very few of the built and social environmental variables were ii significantly associated with PA or overweight/obesity. Greater park area was significantly associated with total PA in females. Greater green space was shown to be associated with lower odds of male LTPA. Factors from the social environment were generally more strongly related to male outcomes. Further to the recreation and social environment, factors in the food landscape were significantly associated with male and female PA and overweight/obesity. Results of the directly measured PA and BMI investigation showed significant neighbourhood-group effects for light intensity PA and sedentary time. Post-hoc tests identified that the low REC/high SES neighbourhood had significantly more minutes of light PA than the low REC/low SES. BMI differed between the four neighbourhoods, but the differences were not significant after controlling for age, sex and household income. Conclusions: Results of this dissertation show that the quantity of PA can differ based on its method of measurement (i.e. between self-report and direct methods) with implications for the interpretation of study findings. It also identifies that PA and BMI can differ by neighbourhood and recognizes that the relationships between neighbourhood environments and PA and body composition are complex, may be differ between males and females, and may not always follow intuitive relationships. Furthermore it suggests that other factors in the environment not examined in this dissertation may influence adult PA and BMI and that longitudinal and intervention studies are needed.

Übergewicht und Adipositas bei Kindern und Jugendlichen stellen ein weltweit zunehmendes Gesundheitsproblem dar und sind zur häufigsten chronischen Erkrankung des Kindes- und Jugendalters in der entwickelten Welt geworden. Nicht nur die Prävalenz der Adipositas ist in den letzten 25 Jahren gestiegen, sondern auch der absolute BMI. Die kindliche Adipositas stellt nicht nur ein kosmetisches Problem dar, sondern einen Risikofaktor etwa für Herzerkrankungen, Diabetes mellitus oder Störungen des Bewegungsapparates. Voraussetzung für erfolgreiche Präventions- und Interventionsprogramme ist ein Bewusstsein für Übergewicht und der Wille zur Gewichtsreduktion bei den betroffenen Kindern sowie bei deren Eltern. Diese Dissertation hat daher zwei Ziele: Zunächst wird untersucht, wie Kinder sich und ihren Körper im Vergleich zum tatsächlichen Gewichtsstatus einschätzen. Darüber hinaus wird der Frage nachgegangen, ob Eltern das Vorliegen von Übergewicht oder Adipositas bei ihrem Kind erkennen. Die Dissertation besteht aus einem Artikel. Darin wird gezeigt, dass die meisten Kinder und Jugendlichen sowie ihre Eltern die Adipositas als ein Gesundheitsproblem erkennen. Eine Mehrheit der Kinder und Jugendlichen schätzt ihren eigenen Gewichtsstatus realistisch ein. Die Mehrheit der Eltern erkennt zumindest Übergewicht bei ihrem Kind. Das Ausmaß wird jedoch häufig unterschätzt.

Children’s lifestyle has changed significantly during the recent decades, with an increasing prevalence of obesity as one outcome. Parents are usually the most influential people in young children’s lives. The overall aim of this thesis was to investigate parental perspectives on factors associated with 3-6 year-old children’s lifestyle, regarding eating habits and physical activity. Another objective was to compare different approaches to conducting postal questionnaires in terms of response rate, time consumption and cost-efficiency. The samples in the four studies were parents of 6-year-olds (n=158), parents of 3-year-olds (n=873), parents of 4-year-olds (n=30) and parents of 3-year-olds (n=353). In the first study, a questionnaire regarding practices and attitudes towards their child’s lifestyle, perceived obstacles and desired support was used. The second study included the Swedish Parenthood Stress Questionnaire (SPSQ), the Relationship Questionnaire (RQ) and the CFQ (Child Feeding Questionnaire). Parents also reported their child’s TV-viewing habits. The child’s measured height, weight and BMI were obtained from a register, BASTA. In the third study, focus group interviews were performed. The fourth study investigated three types of consent given for participation in a survey. The results showed that parents’ attitudes towards children’s lifestyle, in general, were “healthier” than their reports of their child’s daily practices. The practices differed depending on the parents’ educational background. Significant and dose-dependant associations were found between perceived maternal stress and children’s overweight, but also underweight. Parents felt that they were mainly responsible for their preschool child’s lifestyle. However, parents described challenges that limited and obstructed them from providing their child with a healthy lifestyle, citing the need to receive professional and peer support, while also requesting support from society. Allowing respondents to actively decline participation yielded a higher response rate and proved to be the most cost-efficient method for conducting a postal questionnaire.

The increasing prevalence of overweight and obesity in young people is a major global public health concern, especially in developed countries. In Australia, studies in 2001 have suggested that 20% of boys and 21.5% of girls aged 7-15 years were overweight or obese, while in 1985 the figures were 10.7% and 11.8%, respectively. In the short-term, overweight and obese children and adolescents suffer from both adverse physical and psychological consequences. The most significant long-term consequence of childhood obesity is its persistence into adulthood, along with numerous associated health risks. A number of studies have shown that there is an association between being an overweight child and subsequent adulthood obesity. In general, childhood overweight and obesity is a multifactorial disease and its development is due to multiple interactions between genes and environment. A number of risk factors such as socioeconomic status, dietary patterns, and physical activity have been frequently identified as contributors to its development. However, the results of recent studies provide conflicting evidence. The statistical limitations also make it difficult to compare the studies on childhood obesity between countries. In addition, existing research in Australia that examines the contribution of different risk factors to childhood obesity is limited. There are no published data on the relationship between overweight/obesity, dietary patterns, and physical activity/inactivity in Australian children and adolescents. This study examined the influences of household income, dietary factors, physical activity/inactivity and ethnicity on overweight and obesity among Australian children and adolescents. It also explored the relationship between self-reported weight and height to actual weight and height in older Australian adolescents in order to clarify the accuracy of self-reported data among Australian youth. Data from the two national cross-sectional surveys, the 1995 Australian National Health Survey (NHS) and the 1995 National Nutrition Survey (NNS) were analysed to explore the influences of household income, intake of energy and fat and percentage of energy from fat on childhood obesity. The study focused on 1585 children and adolescents aged 7-15 years. These data were also used to examine the relationship of self-reported weight and height to measured weight and height in older adolescents. Additionally, another cross-sectional survey among a group of Australian primary school children from a multi-cultural school in southern Brisbane was undertaken as well as providing indicative data on the relationship of overweight/obesity to physical activity levels and ethnicity, and to provide a protocol on the methodology and practicality of measuring physical activity level in such a school setting. The results suggested that boys from households with low incomes were more likely to be overweight or obese compared with those from households with higher incomes. Having parents, especially mothers, who were overweight or obese increased the risk of children being overweight or obese. The results do not provide evidence that there are statistically significantly differences in the average intake of energy and fat and percentage of energy from fat between non-overweight and overweight or obese boys and girls. The correct classification of weight or obesity from self-reported height and weight by Australian older adolescents was about 70%, bias in reporting weight and height is higher among overweight or obese older adolescents than non-overweight counterparts. In addition, preliminary, indicative data from the pilot study on the relationship between body mass index (BMI) and physical activity in 10-12 year old Australian school children from a multi-cultural school revealed that the average daily physical activity level (PAL) was 2.3 Metabolic Equivalents (METs) when the PAL was measured using self-reported activity diary. The proportion of light, moderate and heavy PAL was 2.9%, 20.4% and 76.7% in children, respectively. Additionally no ethnic differences in the prevalence of overweight /obesity was found. There was no statistically significant difference in average daily TV view times between non-overweight and overweight or obese boys and girls. The average daily number of steps measured using pedometer in the weekdays was 16,505 in boys and 12766 in girls. Most of boys (94.0%) have a medium and over level of steps taken daily while nearly one-third of the girls had not reached the minimum level in the number of steps for optimal health. However it must be noted this school-based study was a small cross-sectional survey in a single school. The results should be viewed as indicative, not generalisable. The study does not provide any longitudinal data on physical activity patterns and the trends in relationship to body mass index. In spite of the limitations of this study, it did provide some preliminary data on PAL and its relationship to overweight/ obesity among young Australian schoolchildren from diverse cultural backgrounds. Most importantly, this pilot study has provided a protocol on the methodology and practicality of measuring physical activity levels of children using self-reported activity diaries and pedometers in a multicultural school setting. A number of strategies for the prevention and treatment of childhood overweight and obesity are discussed. In future studies, a population-based and randomly selected sample would ensure findings that are more representative of general Australian children, and the longitudinal studies would help to define the association between the risk factors and childhood obesity, as well as enabling conclusions on causality to be drawn.