Dietary factors, obesity and serum lipoprotein profile : A nutritional epidemiological study in young adult twins

Background: Energy-dense food and low physical activity have been blamed for the dramatic rise in the prevalence of obesity and related metabolic disorders. However, few dietary and physical activity factors have been consistently associated with obesity in observational studies. Self-reported behaviors are prone to misreporting, which may partly explain the inconsistency of previous results. Nutritional biomarkers provide an objective approach to measure habitual intake, but valid biomarkers are not available for all types of dietary exposures. Aims: The aims of this dissertation were to 1) validate self-reported dietary intake and physical activity by using objective co-twin comparison assessments (I) and the doubly labeled water (DLW) technique (II); 2) determine whether eating and physical activity behaviors are associated with body mass index (BMI) and waist circumference (WC) (I, II); 3) examine whether acquired obesity (IV) and dietary factors (III, V) are associated with serum lipoprotein profiles. Materials and methods: The following participants were recruited from the FinnTwin12 and FinnTwin16 studies, two population-based studies on young adult Finnish twins: 1) 713 monozygotic (MZ) and 698 dizygotic (DZ) twin pairs of the same sex who filled in food-frequency questionnaires (FFQ) and co-twin comparison questions (I); 2) 14 MZ twin pairs discordant (BMI difference more than 3kg/m2) and 10 pairs concordant for obesity who provided 3-day food and activity diaries, eating behavior questionnaires, co-twin comparison questions and total energy expenditure (TEE) measurements determined by DLW (II); 3) 15 obesity-discordant and 9 concordant MZ twin pairs who completed 3-day food diaries, physical activity questionnaires and measurements of subcutaneous adipose tissue, visceral adipose tissue and liver fat by magnetic resonance imaging and spectroscopy and of serum lipid determinations by ultracentrifugation, gradient gel electrophoresis and enzymatic techniques (III, IV); 4) 663 twin individuals who provided FFQs and nuclear magnetic resonance spectroscopy-derived measurements of serum lipoproteins and serum docosahexaenoic acid (DHA) as an objective biomarker of DHA intake (V). Results: In both zygosity groups, the co-twins for whom both twin pair members concordantly answered that the identified twin eats more (overall), or eats more fatty foods, or eats more sweet and fatty delicacies, or eats faster, or selects food less according to healthiness or makes less active choices in daily life had significantly higher BMIs and WCs than their twin siblings. Eating more (overall), eating more sweet and fatty delicacies and exercising less remained significant predictors of intrapair differences in BMI and WC independent of each other as evaluated by multivariate regression analysis. Co-twin comparison questions on snacking, fatty foods, sweet and fatty delicacies and healthy foods corresponded well with self-reported food intake in the FFQs. Twin pairs who differed in the overall amount of food they consumed had the largest intrapair differences in BMI (MZ: 1.9 ± 0.1, DZ: 2.9 ± 0.2 kg/m2) and WC (MZ: 5.5 ± 0.6, DZ: 7.5 ± 0.7 cm). However, there were no differences in self-reported intake between these pairs (I). Analysis of obesity-discordant MZ twin pairs confirmed these results, as most pairs agreed that the heavier twins ate more (overall), snacked more and exercised less than the leaner co-twins. Eating behaviors such as eating too much, striving to be thin and body dissatisfaction were more frequently reported by obese co-twins than their lean counterparts. Total energy intake did not differ between the obese and lean co-twins and few differences were found in the 3-day food diary data. Underreporting of actual energy intake was significant for the obese (24.7% of TEE) but not for the lean co-twins (8.4% of TEE) (II). Obesity-discordant pairs differed significantly in their serum lipoprotein profiles, and the acquired accumulation of liver fat was particularly associated with increased concentrations of atherogenic lipids, including low-density lipoprotein (LDL-C) and Apolipoprotein B (ApoB), while physical activity was related to reduced concentrations of atherogenic lipids (IV). Omega-3 polyunsaturated fatty acid intake, as evaluated by self-reporting and serum measurements of DHA, was significantly related to a shift in the serum high-density lipoprotein (HDL) subclass distribution toward larger HDL particle size (III, V). In addition, serum DHA was positively associated with serum LDL particle diameter and negatively associated with triglyceride (TG) concentrations, medium and large very-low density lipoprotein (VLDL) particle concentrations and VLDL particle diameter. A high-fat, high-sucrose, low fiber dietary pattern (labeled junk food ) was positively associated with TG concentrations, a shift in the subclass distribution of VLDL toward larger particles and LDL toward smaller particles, and an increased concentration of small HDL particles in the serum (V). The associations were independent of adiposity and other lifestyle factors, and most were independent of the potential confounding effects of genotype and early environmental factors shared by twins. Conclusions: By using mutual responses of twin pairs, this study provides compelling evidence that acquired eating and physical patterns are important determinants of obesity, but they may be overlooked in population studies that use self-reported data due considerable misreporting of actual energy intakes and exercise behavior by obese subjects. Habitual physical activity and fish intake were related to a favorable serum lipoprotein profile, whereas a high-fat, high-sucrose, low-fiber dietary pattern and accumulation of liver fat associated with an unfavorable serum lipoprotein profile. These results emphasize a healthy lifestyle, in particular reduced portion sizes of energy-dense, nutrient poor foods and regular physical activity as the cornerstone of preventing obesity and lipid disturbances in young adults.Tausta: Energiatiheää ravintoa ja vähäistä liikuntaa on pidetty lihavuuden ja siihen liittyvien aineenvaihduntahäiriöiden huomattavan lisääntymisen syinä. Havainnointitutkimuksissa lihavuuteen on kuitenkin johdonmukaisesti liitetty vain joitakin ruokavalioon ja liikuntaan liittyviä tekijöitä. Kun henkilö ilmoittaa itse käyttäytymisestään, raportit sisältävät herkästi virheitä, mikä saattaa ainakin osittain selittää aiempien tulosten epäjohdonmukaisuutta. Ravitsemukselliset biomerkkiaineet edustavat objektiivista lähestymistapaa tavanomaisen ravinnonsaannin mittaamiseen, mutta valideja biomerkkiaineita ei ole käytettävissä kaikille ravintoaltistuksille. Tavoitteet: Tämän väitöskirjan tavoitteina oli 1) validoida itseraportoitua ruoankäyttöä ja liikuntaa objektiivisten kaksossisarukselle tehtyjen objektiivisten vertailukysymysten (I) ja kaksoismerkityn veden avulla (II); 2) määrittää, ovatko syömis- ja liikuntakäyttäytyminen yhteydessä painoindeksiin (BMI) ja vyötärön ympärysmittaan (1, II); ja 3) tutkia, liittyvätkö hankittu lihavuus (IV) ja ruokavaliotekijät (III, V) seerumin lipoproteiiniprofiiliin. Materiaalit ja menetelmät: Tutkimukseen otettiin mukaan seuraavat osallistujat FinnTwin12- ja FinnTwin16-tutkimuksista (kaksi aikuisten nuorten suomalaisten kaksosten populaatiopohjaista tutkimusta): 1) 713 monotsygoottista (eli geneettisesti identtisiä) ja 698 samaa sukupuolta olevaa ditsygoottista kaksosparia (eli ns. epäidenttisiä kaksosia), jotka vastasivat ruokailutiheyteen liittyviin kyselyihin (FFQ) ja kaksossisarukseen liittyviin vertailukysymyksiin (I); 2) 14 monotsygoottista kaksosparia, jotka erosivat lihavuuden suhteen (BMI-ero yli 3kg/m2), ja 10 samanpainoista paria; parit pitivät kolmen päivän ruoka- ja liikuntapäiväkirjoja, vastasivat syömistapakyselyihin ja kaksossisaruksen vertailukysymyksiin sekä osallistuivat kokonaisenergiankulutuksen mittauksiin, jotka tehtiin kaksoisleimatulla vedellä (II); 3) 15 lihavuuden suhteen eroavaa ja 9 samanpainoista monotsygoottista kaksosparia, jotka pitivät kolmen päivän ruokapäiväkirjaa, vastasivat liikuntakyselyihin ja osallistuivat ihonalaisen rasvakudoksen, vatsaontelon sisäisen rasvakudoksen ja maksan rasvan (magneettikuvaus ja magneettispektroskopialla sekä seerumin lipidien mittaukseen (ultrasentrifugointi, gradienttigeelielektroforeesi ja entsymaattiset tekniikat) (III, IV); 4) 663 aikuista kaksosta, jotka vastasivat ruokafrekvenssikyselyihin ja osallistuivat ydinmagneettisella resonanssilla ja spektroskopialla tehtäviin seerumin lipoproteiinien ja seerumin dokosaheksaeenihapon (DHA) mittauksiin, joista jälkimmäinen toimi DHA:n saannin objektiivisena biomerkkiaineena. Tulokset: Sekä mono- että ditsygoottiryhmissä niillä kaksossisaruksilla, joiden kohdalla kaksosparin molemmat kaksossisarukset vastasivat yhdenmukaisesti, että kyseinen kaksonen joko syö enemmän (yhteensä), syö rasvaisempia ruokia, syö rasvaisia herkkuja, syö nopeammin, ajattelee ruokaa valitessaan ruuan terveellisyyttä vähemmän kuin toinen kaksonen tai tekee arkielämässä vähemmän liikunnallisesti aktiivisia valintoja, oli merkitsevästi suuremmat painoindeksit ja vyötärönympärykset kuin heidän kaksossisaruksillaan. Enemmän syöminen (yhteensä), rasvaiset herkut ja vähäisempi liikunta säilyivät parinvälisten erojen merkitsevinä ennustajina monitekijäisessä regressioanalyysissä toisistaan riippumatta. Kaksossisarusten vertailukyselyt napostelusta, rasvaisista ruuista, rasvaisista herkuista ja terveellisistä ruuista vastasivat hyvin ruokafrekvenssikyselyissä itseraportoitua ravinnonsaantia. Niillä kaksospareilla, joilla ruuan nautittu kokonaismäärä oli erilainen, oli suurin parinsisäinen ero painoindeksissä (monotsygootit: 1,9 ± 0,1, ditsygootit: 2,9 ± 0,2 kg/m2) ja vyötärönympäryksessä (monotsygootit: 5,5 ± 0,6, ditsygootit: 7,5 ± 0,7 cm). Näiden parien välillä ei kuitenkaan ollut eroja itseraportoidussa ravinnonsaannissa (I). Monotsygoottisten, lihavuuden suhteen eroavien kaksosten analysointi varmisti nämä tulokset, sillä useimmat kaksossisarukset kertoivat, että painavampi kaksonen syö enemmän (yhteensä), napostelee useammin ja liikkuu vähemmän kuin laihempi kaksosista. Lihavat kaksossisarukset raportoivat laihoja useammin liiallista syömistä, halua laihtua ja tyytymättömyyttä omaa kehoa kohtaan. Energiansaannin kokonaismäärä ei poikennut näiden lihavien ja laihojen kaksossisarusten välillä, ja kolmen päivän ruoka- ja liikuntapäiväkirjojen välillä havaittiin vain vähän eroja. Energiansaannin aliraportointi on merkitsevää lihavilla (24,7 % kokonaisenergian-saannista), mutta ei laihoilla (8,4 % kokonaisenergiansaannista) kaksossisaruksilla (II). Lihavuuden suhteen eroavilla pareilla oli merkitsevästi erilaiset lipoproteiiniprofiilit, ja erityisesti maksaan kertynyt rasva liittyi aterogeenisten lipidien (LDL-C, ApoB) lisääntyneisiin pitoisuuksiin ja liikunta niiden pienentyneisiin pitoisuuksiin (IV). Itseraportoitujen tietojen ja DHA-seerumimittausten arvioinnin perusteella monityydyttymättömän omega-3-rasvahapon saanti liittyi merkitsevästi HDL-alaluokan jakautumiseen suuremman HDL-partikkelikoon suuntaan (III, V). Seerumin DHA-pitoisuus liittyi lisäksi positiivisesti LDL-partikkelin läpimittaan ja negatiivisesti triglyseridipitoisuuteen ja keskikokoisten ja isojen VLDL- ja VLDL-partikkelien läpimittaan. Runsasrasvainen, runsaasti sakkaroosia sisältävä, vähäkuituinen ruokavalio ("roskaruoka") liittyi korkeampiin triglyseridipitoisuuksiin, VLDL:n alaluokkajakautuman siirtymiseen suurempien partikkelien suuntaan ja LDL:n siirtymiseen pienempien partikkeleiden suuntaan sekä pienten HDL-partikkelien suurentuneeseen pitoisuuteen (V). Nämä yhteydet olivat lihavuudesta ja muista elämäntapatekijöistä riippumattomia, ja useimmat olivat myös kaksosten yhteisen genotyypin ja varhaisten ympäristötekijöiden mahdollisista sekoittavista vaikutuksista riippumattomia. Päätelmät: Tämä tutkimus antaa kiistatonta näyttöä siitä, että omaksutut syömis- ja liikuntatottumukset ovat tärkeitä lihavuutta selittäviä tekijöitä, mutta näitä eroja ei ehkä huomata populaatiotutkimuksissa itseraportoituja tietoja käytettäessä, mikä johtuu lihavien tutkittavien virheellisestä itseraportoinnista. Liikunta ja kalan nauttiminen liittyivät edulliseen seerumin lipoproteiiniprofiiliin, ja runsasrasvainen, runsaasti sakkaroosia sisältävä, vähäkuituinen ruokavalio ja rasvan kertyminen maksaan liittyivät epäsuotuisaan profiiliin. Nämä tulokset korostavat terveellisen ruokavalion, erityisesti vähäisen energiatiheiden, niukasti suojaravintoaineita sisältävien ruokien käytön ja säännöllisen liikunnan merkitystä lihavuuden ja lipidihäiriöiden ehkäisemisessä nuorilla aikuisilla

Nutrient intake and it´s association with bone mineral density in postmenopausal Finnish women

Einleitung: Die Ernährung spielt bei der Prävention von Osteoporose eine große Rolle. Während die Bedeutung einer ausreichenden Versorgung mit Calcium und Vitamin D generell akzeptiert ist, stehen viele andere Ernährungsfaktoren, wie die Aufnahme von Obst und Gemüse in der Literatur zur Diskussion. Ziel der Arbeit: Ziel der vorliegenden Arbeit war es, die Nährstoffaufnahme postmenopausaler finnischer Frauen mittels eines semiquantitativen Häufigkeitsfragebogens (Food Frequency Questionnaire; FFQ) zu ermitteln. Ein weiteres Ziel dieser Arbeit war es den Zusammenhang zwischen der Nährstoffaufnahme, sowie zwischen dem Obst- und Gemüseverzehr und der Knochendichte am Schenkelhals und an der Lendenwirbelsäule zu untersuchen. Material und Methoden: Die Studienteilnehmer waren 101 postmenopausale Frauen im Alter zwischen 68 und 74 Jahren. Die Knochendichte wurde mittels Energien- Röntgen- Absorptiometrie (Dual Energy X-ray Absorptiometry; DXA) am Schenkelhals und an der Lendenwirbelsäule gemessen. Die Nährstoffzufuhr wurde mit einem aus 89 Die Nährstoffzufuhr wurde mittels eines 89 Fragen beinhaltenden, semiquantitatien FFQs ermittelt. Die finnische online Nährwertdatenbank Fineli (www.fineli.fi) wurde verwendet um aufgenommen Lebensmittel in Nährwerte umzurechnen. Die Nährstoffberechung und alle statistischen Auswertungen wurden mit dem Statistikprogramm SPSS für Windows durchgeführt. Alle Studienteilnehmer wurden für jeden Nährstoff in 2 gleich große Gruppen (über und unter dem Median) eingeteilt. Die Gruppenunterteilung wurde durchgeführt, um eventuelle Unterschiede in der mittleren Knochendichte zwischen der Gruppe mit hoher Nährstoffaufnahme (bzw. hohem Obst- und Gemüsekonsum) und niedriger Nährstoffaufnahme (bzw. niedrigem Obst- und Gemüsekonsum) festzustellen. Unterschiede zwischen den Gruppen wurden unter Berücksichtung der konfundierenden Variablen mittels ANOVA (univariate Varianzanalyse) getestet. Ergebnisse: Die DEXA Messwerte der Knochendichte am Schenkelhals ergaben 0.83 ± 0.12 g/cm2 und an der Lendenwirbelsäule 1.08 ± 0.18 g/cm2. Die Erfassung der Energiezufuhr mittels FFQ ergab eine mittlere tägliche Energieaufnahme von 2173 ± 554 kcal. Die Aufnahme von Protein lag bei 17%, die von Fett bei 31% und die von Kohlenhydraten bei 51% der gesamten täglichen Energieaufnahme. Die Aufnahme von Obst und Gemüse betrug im Durchschnitt 649 ± 435 gram täglich. Frauen mit der höchsten Aufnahme von Magnesium wiesen eine signifikant höhere Knochendichte am Oberschenkelhals auf, jedoch war das Ergebnis nach statistischer Kontrolle konfundierender Variablen nicht mehr signifikant. Eine niedrige Vitamin D Aufnahme mit der Nahrung stand mit einer geringeren Knochendichte am Oberschenkelhals in Zusammenhang und das Ergebnis blieb auch nach Berücksichtigung aller konfundierenden Variablen signifikant (p<0.05)

Dietary n-6 to n-3 fatty acid ratio is related to liver fat content independent of genetic effects : Evidence from the monozygotic co-twin control design

Background & aim: Lifestyle changes focusing on diet and exercise remain the cornerstone of the treatment of non-alcoholic fatty liver disease (NAFLD). The present co-twin control study of monozygotic (MZ) twin pairs was designed to identify nutritional factors potentially involved in the pathogenesis of NAFLD. Methods: Cross-sectional study of 50 MZ twin pairs (age range: 23-36 years), of which ten pairs were discordant for liver fat (liver fat percentage of one twin 5% and a difference between co-twins of >5%) as determined by magnetic resonance spectroscopy. Nutrient intake was calculated from 3-day food records. Results: Among the ten liver fat-discordant twin pairs, the n-6: n-3 ratio was significantly higher in the twins with higher liver as compared to their co-twins with lower liver fat (6.6:1 vs. 3.2:1, p-value = 0.005). In multiple regression analysis of within-pair differences including all 50 twin pairs, a higher n-6: n-3 ratio was significantly associated with a higher liver fat percentage within MZ twin pairs after adjustment for body mass index, energy intake and other covariates (standardized beta = 0.43, p-value = 0.001). Conclusions: Our findings suggest that the n-6: n-3 ratio is a promising dietary agent for the prevention and treatment of NAFLD. Clinical trials are required to better understand causal relationships and required doses. (C) 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.Peer reviewe

Meal-timing patterns and chronic disease prevalence in two representative Austrian studies

PURPOSE This study aimed at describing meal-timing patterns using cluster analysis and explore their association with sleep and chronic diseases, before and during COVID-19 mitigation measures in Austria. METHODS Information was collected in two surveys in 2017 (N = 1004) and 2020 (N = 1010) in representative samples of the Austrian population. Timing of main meals, nighttime fasting interval, last-meal-to-bed time, breakfast skipping and eating midpoint were calculated using self-reported information. Cluster analysis was applied to identify meal-timing clusters. Multivariable-adjusted logistic regression models were used to study the association of meal-timing clusters with prevalence of chronic insomnia, depression, diabetes, hypertension, obesity and self-rated bad health status. RESULTS In both surveys, median breakfast, lunch and dinner times on weekdays were 7:30, 12:30 and 18:30. One out of four participants skipped breakfast and the median number of eating occasions was 3 in both samples. We observed correlation between the different meal-timing variables. Cluster analysis resulted in the definition of two clusters in each sample (A17 and B17 in 2017, and A20 and B20 in 2020). Clusters A comprised most respondents, with fasting duration of 12-13 h and median eating midpoint between 13:00 and 13:30. Clusters B comprised participants reporting longer fasting intervals and later mealtimes, and a high proportion of breakfast skippers. Chronic insomnia, depression, obesity and self-rated bad health-status were more prevalent in clusters B. CONCLUSIONS Austrians reported long fasting intervals and low eating frequency. Meal-timing habits were similar before and during the COVID-19-pandemic. Besides individual characteristics of meal-timing, behavioural patterns need to be evaluated in chrono-nutrition epidemiological studies

Sport disciplines, types of sports, and waist circumference in young adulthood - a population-based twin study

Purpose: The benefits of physical activity (PA) in preventing abdominal obesity are well recognized, but the role of different sport disciplines remains open. We aimed, therefore, to investigate how participation in different sport disciplines, and the number and types of sports engaged in are associated with waist circumference (WC) in young adulthood. Methods: This population-based cohort study comprised 4027 Finnish twin individuals (1874 men), with a mean age of 34 y (32-37), who answered a survey, including self-measured WC. We extracted the number and identified the types (aerobic, power, and mixed) of the different sport disciplines respondents reported participating in. Results: The number of sport disciplines participated in was inversely associated with WC, the linear decrease averaging 1.38cm (95% CI 1.10-1.65) per each additional sport discipline. The result persisted after adjustment for the main covariates, such as volume of PA and diet quality. Among dizygotic twin pairs discordant for sports participation (0-2 vs. 5 or more disciplines), the mean within-pair difference in WC was 4.8cm (95% CI 0.4-9.1) for men and 11.2cm (95% CI 4.4-18.0) for women; among discordant monozygotic pairs, no differences were observed. In men, all three types of sports were individually associated with smaller WC, while in women, only mixed and power sports showed this association. Conclusions: Participation in several sport disciplines and sport types was associated with smaller WC among young adults in their mid-30s. Shared genetic background may explain some of the associations.Peer reviewe

Eating Behaviors in Healthy Young Adult Twin Pairs Discordant for Body Mass Index

We aimed to study the eating behavioral traits that associate with body mass index (BMI) among BMI-discordant twin pairs. This cross-sectional study examined self-reported eating behaviors in 134 healthy young adult twin pairs (57 monozygotic [MZ] and 77 same-sex dizygotic [DZ]), of whom 29 MZ and 46 DZ pairs were BMI discordant (BMI difference >= 3 kg/m(2)). In both MZ and DZ BMI-discordant pairs, the heavier co-twins reported being less capable of regulating their food intake optimally than their leaner co-twins, mainly due to 'frequent overeating'. Furthermore, the heavier co-twins reported augmented 'disinhibited eating', 'binge-eating scores' and 'body dissatisfaction'. The twins agreed more frequently that the heavier co-twins (rather than the leaner co-twins) ate more food in general, and more fatty food, in particular. No significant behavioral differences emerged in BMI-concordant twin pairs. Overeating - measured by 'frequent overeating', 'disinhibited eating' and 'binge-eating score' - was the main behavioral trait associated with higher BMI, independent of genotype and shared environment.Peer reviewe

Weight Status and BMI-Related Traits in Adolescent Friendship Groups and Role of Sociodemographic Factors : The European IDEFICS/I.Family Cohort

Background: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. Methods: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. Results: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. Conclusion: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987).Peer reviewe

Family structure in relation to body mass index and metabolic score in European children and adolescents

Background Living in single parent and blended families or as an only child-compared to living in two-parent biological families or with siblings, respectively-is associated with a higher body mass index (BMI) in cross-sectional studies. However, longitudinal research addressing the children's BMI in this context is scarce. Further, little is known about the association between family structure and metabolic health. Objectives This study aimed at investigating the association between both aspects of family structure with BMI and a metabolic score (MetS). Methods Cross-sectional data from 7804 children participating in the European multi-center I.Family study (2013/2014) and longitudinal data from 5621 children who also participated previously in the IDEFICS study (2007-2010) were used. Family structure was assessed by a detailed interview. BMI z-score and the MetS were based on measured anthropometry, blood pressure, high-density lipoprotein, blood glucose, and triglycerides. Linear regressions were performed to model associations between family structure with BMI and MetS. Results Children from single-parent families had higher BMI z-scores in the cross-sectional (beta = 0.09, 95% confidence interval [CI]: 0.001 to 0.18) and longitudinal analyses compared to those from two-parent families. Cross-sectionally, the number of siblings was associated with lower BMI z-scores (beta = -0.07, 95% CI: -0.10 to -0.03) and lower MetS (beta = -0.14, 95% CI: -0.26 to -0.01). Longitudinally, only children between baseline and follow-up had higher BMI z-scores at follow-up (beta = 0.07, 95% CI: 0.01 to 0.14) compared to stable siblings. Conclusion Obesity prevention measures should focus on single-parent households and families with an only child.Peer reviewe

The genetic architecture of the association between eating behaviors and obesity : combining genetic twin modeling and polygenic risk scores

Background Obesity susceptibility genes are highly expressed in the brain suggesting that they might exert their influence on body weight through eating-related behaviors. Objectives To examine whether the genetic susceptibility to obesity is mediated by eating behavior patterns. Methods Participants were 3977 twins (33% monozygotic, 56% females), aged 31–37 y, from wave 5 of the FinnTwin16 study. They self-reported their height and weight, eating behaviors (15 items), diet quality, and self-measured their waist circumference (WC). For 1055 twins with genome-wide data, we constructed a polygenic risk score for BMI (PRSBMI) using almost 1 million single nucleotide polymorphisms. We used principal component analyses to identify eating behavior patterns, twin modeling to decompose correlations into genetic and environmental components, and structural equation modeling to test mediation models between the PRSBMI, eating behavior patterns, and obesity measures. Results We identified 4 moderately heritable (h2 = 36–48%) eating behavior patterns labeled “snacking,” “infrequent and unhealthy eating,” “avoidant eating,” and “emotional and external eating.” The highest phenotypic correlation with obesity measures was found for the snacking behavior pattern (r = 0.35 for BMI and r = 0.32 for WC; P 70%). The snacking behavior pattern partially mediated the association between the PRSBMI and obesity measures (βindirect = 0.06; 95% CI: 0.02, 0.09; P = 0.002 for BMI; and βindirect = 0.05; 95% CI: 0.02, 0.08; P = 0.003 for WC). Conclusions Eating behavior patterns share a common genetic liability with obesity measures and are moderately heritable. Genetic susceptibility to obesity can be partly mediated by an eating pattern characterized by frequent snacking. Obesity prevention efforts might therefore benefit from focusing on eating behavior change, particularly in genetically susceptible individuals.Peer reviewe

The temporal relationship between parental concern of overeating and childhood obesity considering genetic susceptibility : longitudinal results from the IDEFICS/I.Family study

Background: Many genes and molecular pathways are associated with obesity, but the mechanisms from genes to obesity are less well known. Eating behaviors represent a plausible pathway, but because the relationships of eating behaviors and obesity may be bi-directional, it remains challenging to resolve the underlying pathways. A longitudinal approach is needed to assess the contribution of genetic risk during the development of obesity in childhood. In this study we aim to examine the relationships between the polygenic risk score for body mass index (PRS-BMI), parental concern of overeating and obesity indices during childhood. Methods: The IDEFICS/I.Family study is a school-based multicenter pan-European cohort of children observed for 6 years (mean +/- SD follow-up 5.8 +/- 0.4). Children examined in 2007/2008 (wave 1) (mean +/- SD age: 4.4 +/- 1.1, range: 2-9 years), in 2009/2010 (wave 2) and in 2013/2014 (wave 3) were included. A total of 5112 children (49% girls) participated at waves 1, 2 and 3. For 2656 children with genome-wide data we constructed a PRS based on 2.1 million single nucleotide polymorphisms. Z-score BMI and z-score waist circumference (WC) were assessed and eating behaviors and relevant confounders were reported by parents via questionnaires. Parental concern of overeating was derived from principal component analyses from an eating behavior questionnaire. Results: In cross-lagged models, the prospective associations between z-score obesity indices and parental concern of overeating were bi-directional. In mediation models, the association between the PRS-BMI and parental concern of overeating at wave 3 was mediated by baseline z-BMI (beta = 0.16, 95% CI: 0.10, 0.21) and baseline z-WC (beta = 0.17, 95% CI: 0.11, 0.23). To a lesser extent, baseline parental concern of overeating also mediated the association between the PRS-BMI and z-BMI at wave 3 (beta = 0.10, 95% CI: 0.07, 0.13) and z-WC at wave 3 (beta = 0.09, 95% CI: 0.07, 0.12). Conclusions: The findings suggest that the prospective associations between obesity indices and parental concern of overeating are likely bi-directional, but obesity indices have a stronger association with future parental concern of overeating than vice versa. The findings suggest parental concern of overeating as a possible mediator in the genetic susceptibility to obesity and further highlight that other pathways are also involved. A better understanding of the genetic pathways that lead to childhood obesity can help to prevent weight gain.Peer reviewe