Familial Resemblance in Eating Behaviors in Men and Women from the Quebec Family Study

Objective: It is commonly recognized that genetic, environmental, behavioral, and social factors are involved in the development of obesity. The family environment may play a key role in shaping children's eating behaviors. The purpose of this study was to estimate the degree of familial resemblance in eating behavioral traits (cognitive dietary restraint, disinhibition, and susceptibility to hunger). Research Methods and Procedures: Eating behavioral traits were assessed with the Three‐Factor Eating Questionnaire in 282 men and 402 women (202 families) from the Quebec Family Study. Familial resemblance for each trait (adjusted for age, sex, and BMI) was investigated using a familial correlation model. Results: The pattern of familial correlation showed significant spouse correlation for the three eating behavior phenotypes, as well as significant parent‐offspring and sibling correlations for disinhibition and susceptibility to hunger. According to the most parsimonious model, generalized heritability estimates (including genetic and shared familial environmental effects) reached 6%, 18%, and 28% for cognitive dietary restraint, disinhibition, and susceptibility to hunger, respectively. Discussion: These results suggest that there is a significant familial component to eating behavioral traits but that the additive genetic component appears to be small, with generalized heritability estimates ranging from 6% to 28%. Thus, non‐familial environmental factors and gene‐gene and gene‐environmental interactions seem to be the major determinants of the eating/behavioral traits.     

Gender Differences in Associations of Eating Pathology between Mothers and Their Adolescent Offspring

Objective: To study the association of eating pathology between mothers and their adolescent offspring in a population sample. Research Methods and Procedures: The participants were 481 women (mean age, 47 ± SD 5 years; BMI, 25 ± 4 kg/m²) and their 481 adolescent children 16 to 17 years old (BMI, 21 ± 3 kg/m²) of the Stockholm Weight Development Study. Assessment methods were the Three‐Factor Eating Questionnaire Revised 18 and the Eating Disorder Inventory 2. Results: A higher body weight was most related to cognitive restraint for adolescents and to emotional eating for adult women. A mother‐daughter link could be identified for eating pathology, with the strongest link found for emotional eating. No mother‐son link could be identified. Age subgroup analyses revealed a stronger mother‐daughter link for body attitudes in younger mothers and for cognitive restraint in older mothers. Discussion: Gender differences revealed that eating pathology was shared by mothers and daughters but not by mothers and sons. A psychological strategy such as eating as a response to negative emotions was most interrelated between mothers and daughters. Younger mothers shared more attitudes toward the body with their daughters, whereas older mothers shared more restrictive eating behaviors with their daughters. The mother‐daughter links found may be due to gender‐specific genetic and psychological family transmission and gender‐specific environmental influences. The sons’ eating behaviors seem to be more independent and would be formed by other factors than for the girls.     

On the Relation of Attempting to Lose Weight,Restraint, and Binge Eating in Outpatients with Binge Eating Disorder

Objective: To examine the relationship among attempts to lose weight, restraint, and eating behavior in outpatients with binge eating disorder (BED). Research Methods and Procedures: Participants were 93 consecutive outpatients evaluated for a clinical trial who met Diagnostic and Statistical Manual, Fourth edition criteria for BED. The Eating Disorder Examination Interview was administered to assess attempts at weight loss, restraint, different forms of overeating, and the attitudinal psychopathology of eating disorders (i.e., concerns regarding eating, shape, and weight). In addition, the Three‐Factor Eating Questionnaire was used to assess cognitive restraint, hunger, and disinhibition. Psychometrically established measures were given to assess body dissatisfaction, depression, and self‐esteem. Results: The majority of participants (75.3%; N = 70) reported attempting to lose weight, but only 37.6% (N = 35) reported dietary restraint on at least half the days of the month. Dietary restraint and cognitive restraint were not associated with any form of binge eating or overeating. Dietary restraint and cognitive restraint were positively correlated with weight concern, shape concern, and body dissatisfaction, and negatively correlated with body mass index. To further examine the interplay between attempting to lose weight and restraint, three study groups were created: unrestrained nonattempters (21.5%, N = 20), unrestrained attempters (40.9%; N = 38), and restrained attempters (34.4%; N = 32). The three groups did not differ significantly on binge eating or other eating behaviors; however, significant differences were observed for weight concern, shape concern, and body dissatisfaction. Discussion: Attempts to lose weight and restraint are not synonymous for patients with BED. Although 75.3% of BED patients reported that they were attempting to lose weight, only 37.6% reported dietary restraint on at least half the days of the previous month. While restraint was negatively associated with body mass index, it was not related to binge eating or overeating. Our findings raise questions about prevailing models that posit restraint as a predominant factor in the maintenance of binge eating in BED.     

Psychometric properties and construct validity of the Weight-Related Eating Questionnaire in a diverse population

This study evaluates the 16‐item, four‐factor Weight‐Related Eating Questionnaire (WREQ), which assesses theory‐based aspects of eating behavior, across diverse, nonclinical subgroups. A total of 621 men and women aged 18–81 years (34.3 ± 16.4) with a mean BMI of 25.7 ± 6.1 kg/m² (range 15.5–74.1 kg/m²) were recruited from general education classes at the University of Hawai'i, Manoa and an online survey panel of Hawai'i residents to complete a web‐based survey. Participants were predominantly white (23%), Asian/Asian‐mix (42%), or Native Hawaiian/Pacific Islander (18%). The WREQ's factor structure was successfully replicated by confirmatory factor analysis (CFA) for the entire sample and by weight status, gender, age, and race with strong internal consistency. Four‐week test‐retest reliability (n = 31) for the subscales was excellent with interclass correlations of 0.849–0.932. Tests of population invariance confirmed the generalizability of the WREQ across all subgroups having provided no evidence that the factor structure, factor loadings, or indicator intercepts varied significantly between the groups. Multivariate regression analyses showed that emotional eating was independently associated with BMI (β = 0.272, P < 0.001) as well as moderate‐ and long‐term weight change rates (weight gain) in young adults (β = 0.152, P = 0.042) and adults (β = 0.217, P = 0.001). Compensatory restraint was negatively associated with weight gain in adults (β = ?0.133, P = 0.039). Routine restraint and emotional eating were highest among dieters. All associations remained significant after accounting for gender, age, and race. The hypothesized WREQ measurement model demonstrated very good construct validity, confirming the unbiased generalizability of the WREQ measure across sex, age, race, and BMI subgroups, and excellent criterion‐related validity with respect to current BMI, weight change, and weight control status.     

Features and Trajectories of Eating Behavior in Weight‐Loss Maintenance: Results from the German Weight Control Registry

Objective

Eating behaviors such as dietary restraint and disinhibition caused by emotional and external cues play a relevant role in weight‐loss maintenance.

Methods

Four hundred forty individuals with successful weight‐loss maintenance included in the prospective German Weight Control Registry completed the Dutch Eating Behavior Questionnaire. Participants were categorized into the following two weight groups: stable weight trajectory (WS) (n = 280) and unstable weight trajectory (WUS) (n = 160) over the 2‐year assessment period.

Results

Those with successful weight‐loss maintenance had significantly higher scores on the restrained and emotional eating subscales compared with a general population (GP) sample. At baseline, the WS individuals had lower restrained, emotional, and external eating scores compared with the WUS individuals. Over the 2‐year follow‐up period, the trajectories of the restraint scores decreased in both groups but stayed elevated compared with the GP sample. Scores of the emotional and external eating subscales remained stable in the WS group but increased in the WUS group.

Conclusions

A certain degree of restraint seems to be necessary for successful weight‐loss maintenance; however, high emotional and external eating may counteract this effect, resulting in weight regain in the long run.     

The Relationship of Childhood Adiposity to Parent Body Mass Index and Eating Behavior

Objective: To better understand risk factors for the development of obesity in early childhood, we examined the association between children's adiposity and their parents' eating behavior and body mass index (BMI). Research Methods and Procedures: Parents of 85 white children 36 months of age (49 boys and 36 girls) completed the Three‐Factor Eating Questionnaire measuring three dimensions of parent eating behavior: disinhibited eating, cognitive restraint of eating, and susceptibility to hunger. Parent BMI (kg/m²) was calculated using self‐reported height and weight. The children's percentage body fat was assessed by dual energy X‐ray absorptiometry analysis. Results: Twenty‐six percent of parents were obese (BMI ≥ 30 kg/m²). Both maternal and paternal BMI were associated with higher scores for disinhibition (r = 0.69 and r = 0.68, p < 0.001), and maternal BMI was also associated with higher scores for hunger (r = 0.51, p < 0.001). There were no significant relationships between children's percentage body fat and parent eating scores, and the correlation between children's percentage body fat and parent BMI was significant only between mothers and daughters (r = 0.35, p = 0.04). Obese parents were no more likely to have a child who was fatter (upper quintile of percentage body fat for gender). Discussion: Among 36 month‐old white children, parent eating behavior was related to parent BMI, but not to children's adiposity. There was only a weak relationship between parent BMI and child adiposity. Despite the aggregation of adiposity within families due to shared genes and environments, children may not express differences in susceptibility to obesity by 3 years of age.     

Restrained Eating Behavior and the Metabolic Response to Dietary Energy Restriction in Women

Objective: To determine whether prior eating behavior characterized by dietary restraint alters responses in energy expenditure and substrate oxidation associated with a short‐term, energy‐restricted diet. Research Methods and Procedures: A repeated‐measures, 3‐day diet‐intervention study of adequate (125 kJ/kg of body weight) or restricted (62.5 kJ/kg) energy intake was conducted with 30 women, 20 to 46 years, BMI 25 to 45 kg/m², whose prior eating behavior was “restrained” or “unrestrained.” The Eating Inventory (cognitive restraint subscale) was used to measure restrained eating behavior. Energy expenditure and substrate oxidation were measured after a 12‐hour fast and during the first and fourth hours after a standard meal. Plasma glucose, nonesterified fatty acids, and insulin were measured at corresponding times. Body composition was determined by total body electrical conductivity. Results: Resting energy expenditure was not affected by 3 days of energy restriction. Short‐term energy restriction resulted in lower respiratory‐exchange ratios, higher rates of fat oxidation, and lower rates of carbohydrate oxidation. Subjects classified as restrained eaters had higher postprandial respiratory‐exchange ratios and carbohydrate‐oxidation rates compared with unrestrained eaters. Fasting insulin concentrations were lower in restrained eaters. These effects associated with prior eating behavior were independent of the diet intervention. Discussion: Metabolic outcomes associated with a 3‐day energy‐restricted diet (i.e., increased fat oxidation and decreased carbohydrate oxidation) were not affected by prior restrained eating behavior. However, restrained eating behavior was associated with increased carbohydrate oxidation after a mixed meal. This effect of restrained eating behavior may be attributable to increased insulin sensitivity.     

Teasing History,Onset of Obesity,Current Eating Disorder Psychopathology,Body Dissatisfaction,and Psychological Functioning in Binge Eating Disorder

Objective: The primary goal of this study was to examine associations among teasing history, onset of obesity, current eating disorder psychopathology, body dissatisfaction, and psychological functioning in women with Binge Eating Disorder (BED). Research Methods and Procedures: Subjects were 115 female adults who met DSM‐IV criteria for BED. Measurements assessing teasing history (general appearance [GAT] and weight and size [WST] teasing), current eating disorder psychopathology (binge frequency, eating restraint, and concerns regarding eating, shape, and weight), body dissatisfaction, and psychological functioning (depression and self‐esteem) were obtained. Results: History of GAT, but not WST, was associated with current weight concerns and body dissatisfaction, whereas both GAT and WST were significantly associated with current psychological functioning. Patients with earlier onset of obesity reported more WST than patients with later onset of obesity, but the groups did not differ significantly in GAT, current eating disorder psychopathology, body dissatisfaction, or psychological functioning. Obese women reported more WST than non‐obese women, but no differences in GAT or the other outcome variables were observed. Higher frequency of GAT was associated with greater binge frequency in obese women, and with greater eating restraint in non‐obese women. Discussion: Although physical appearance teasing history is not associated with variability in most eating disorder psychopathology, it is associated with related functioning, most notably body dissatisfaction, depression, and self‐esteem. Our findings also suggest that the age of onset of obesity and current body mass index status in isolation are not associated with eating psychopathology or associated psychological functioning in adult patients with BED.     

A twin study of genetic and environmental influences on psychological traits of eating disorders in a Japanese female sample.

The purpose of the present study was to clarify genetic and environmental origins of psychological traits of eating disorders using a Japanese female twin sample. Participants were 162 pairs of female twins consisting of 116 pairs of monozygotic (MZ) twins and 46 pairs of dizygotic (DZ) twins in their adolescence. Psychological traits of eating disorders were assessed with five subscales of the Eating Disorder Inventory (EDI). As a result of using univariate twin analyses, among five subscales of EDI (maturity fears, ineffectiveness, interpersonal distrust, interoceptive awareness, and perfectionism), perfectionism showed significant additive genetic contributions and individual specific environmental effects. On the other hand, maturity fears, ineffectiveness, interoceptive awareness, and interpersonal distrust indicated significant shared environment contributions and individual specific environment effects. The results suggest the importance of both genetic and shared environmental influences on psychological traits of eating disorders in the present study.     

Aspects of eating behaviors "disinhibition" and "restraint" are related to weight gain and BMI in women

Objective: The causes of adult weight gain leading to obesity are uncertain. We examined the association of adult weight gain and obesity with subscales of eating behavior characteristics in older women. Methods and Procedures: Current height and weight, eating behavior subscales (disinhibition subscales—habitual, situational, and emotional; restraint subscales—flexible and rigid; hunger subscales—internal and external) as assessed using the Eating Inventory (EI), and self‐reported body weight at six prior age intervals were reported by 535 women aged 55–65 years. Multiple regression analysis was used to examine the relationships between EI subscale scores and weight change from the age interval of 30–39 to 55–60 years and current BMI. Results: The strongest correlate of weight gain over 20 years was susceptibility to overeating in response to everyday cues within the environment (habitual disinhibition; partial correlation coefficient (r) = 0.25, P < 0.001); susceptibility to overeating in response to emotional states such as depression (emotional disinhibition) was a quantitatively weaker but significant correlate (partial r = 0.17, P < 0.001), and susceptibility to overeating in response to specific situations such as social occasions (situational disinhibition) was not associated with weight gain. Flexible control of dietary restraint attenuated the influence of habitual disinhibition in particular on weight gain and BMI, and was less effective in attenuating associations of emotional or situational disinhibition. Discussion: Lifestyle modification programs for prevention and treatment of adult‐onset obesity currently focus on reducing situational and emotional overeating; the results of this study suggest that a stronger emphasis on strategies that target habitual overeating may be warranted.     

Different Methods for Assessing the Features of Eating Disorders in Patients with Binge Eating Disorder: A Replication

Objective: To compare different methods for assessing the features of eating disorders in patients with binge eating disorder (BED). Research Methods and Procedures: A total of 47 participants with BED were administered the Eating Disorder Examination (EDE) Interview and completed the EDE‐Questionnaire (EDE‐Q) at baseline. A total of 37 participants prospectively self‐monitored their eating behaviors daily for 4 weeks and then completed another EDE‐Q. Results: At baseline, the EDE and the EDE‐Q were significantly correlated on frequencies of objective bulimic episodes (binge eating), overeating episodes, and on the dietary restraint, eating concern, weight concern, and shape concern subscales. Mean differences in the EDE and EDE‐Q frequencies of objective bulimic episodes and overeating were not significant but scores on the four subscales differed significantly, with the EDE‐Q yielding higher scores. At the 4‐week point, the EDE‐Q retrospective 28‐day assessment was significantly correlated with the prospective daily self‐monitoring records for frequency of objective bulimic episodes and the mean difference between the methods was not significant. The EDE‐Q and self‐monitoring findings for subjective bulimic episodes and objective overeating differed significantly. Discussion: In patients with BED, the three assessment methods showed some areas of acceptable convergence.     

Eating Behaviors and Indexes of Body Composition in Men and Women from the Québec Family Study

Objective: To put into relationship the dietary and anthropometric profile of men and women with their eating behaviors (cognitive dietary restraint, disinhibition, and susceptibility to hunger) and to assess whether gender and obesity status influence these associations. Research Methods and Procedures: Anthropometric measurements (including visceral adipose tissue accumulation), dietary profile (3‐day food record), and eating behaviors (Three‐Factor Eating Questionnaire) were determined in a sample of 244 men and 352 women. Results: Women had significantly higher cognitive dietary restraint and disinhibition scores than men (p < 0.0001). In both genders, scores for disinhibition and susceptibility to hunger, but not for cognitive dietary restraint, were higher in obese subjects than in overweight and nonobese subjects (p < 0.05). Positive correlations were observed between rigid restraint and most of the anthropometric variables studied (0.12 ≤ r ≤ 0.16). Moreover, in women, flexible restraint was negatively associated with body fat and waist circumference (r = ?0.11). Cognitive dietary restraint and rigid restraint were positively related to BMI among nonobese women (0.19 ≤ r ≤ 0.20), whereas in obese men, cognitive dietary restraint and flexible restraint tended to be negatively correlated with BMI (?0.20 ≤ r ≤ ?0.22; p = 0.10). Discussion: Gender could mediate associations observed between eating behaviors and anthropometric profile. It was also found that disinhibition and susceptibility to hunger are positively associated with the level of obesity. On the other hand, cognitive dietary restraint is not consistently related to body weight and adiposity, whereas rigid and flexible restraint are oppositely associated to obesity status, which suggests that it is important to differentiate the subscales of cognitive dietary restraint. Finally, counseling aimed at coping with disinhibition and susceptibility to hunger could be of benefit for the long‐term treatment of obesity.     

Binge Eating and Eating‐Related Cognitions and Behavior in Ethnically Diverse Obese Women

Objective: To examine binge eating and eating‐related cognitions and behavior in a sample of ethnically diverse women who are severely obese and seeking bariatric surgery. Research Methods and Procedures: Female bariatric surgery candidates (62 African Americans, 18 Latinas, 130 whites) completed questionnaires on binge eating and eating‐related cognitions and behavior and completed a structured clinical interview to confirm binge‐eating disorder diagnosis. Results: Ethnic minorities and whites did not differ in rates of binge‐eating disorder (26.3%), binges per week (M = 0.95), or dietary restraint. Ethnic minorities reported less disinhibition, and there was a trend to report less hunger awareness than whites. After controlling for BMI and education, ethnicity accounted for significant variance in disinhibition (4%; p < 0.01). Ethnic minorities were younger, became overweight at a later age, and were overweight for fewer years than whites. Discussion: Results suggest that ethnicity exerts an important influence on disinhibition and that ethnic differences are not caused by BMI or education. Findings point to the need to continue to investigate the role of ethnicity, binge eating, and disinhibition in severely obese women, so that culturally appropriate services can be provided.     

Vision and Eating Behavior in Obese Subjects

Objective: Vision is one of a number of factors influencing the amount of food consumed during a meal. The purpose of this study was to investigate the impact of vision on the microstructure of the eating behavior of obese subjects. Research Methods and Procedures: Eighteen obese subjects with a body mass index (mean ± SD) of 39.1 ± 6.3 kg/m² twice consumed a standardized test meal in excess, once with and once without a blindfold. The microstructure of the eating behavior was registered by VIKTOR, a computerized eating monitor. Subjective motivation to eat (i.e., desire to eat, hunger, satiety, and prospective consumption) was rated by visual analogue scales (VASs) before, immediately after, and then hourly up to 3 hours after the test meals. Results: The obese subjects ate 24% less food when blindfolded (359 ± 194 g vs. 472 ± 179 g; p < 0.01). Despite a smaller amount of food consumed when blindfolded, there were no significant differences with or without the blindfold for any of the VASs measuring subjective motivation to eat after test meals. Discussion: The importance of vision in regulating our eating behavior was demonstrated in this study. The obese subjects ate 24% less food blindfolded without feeling less full. Eating blindfolded could be tested as a didactic tool to make obese subjects aware of what factors affect the termination of eating.     

Mediators of Weight Loss and Weight Loss Maintenance in Middle‐aged Women

Long‐term behavioral self‐regulation is the hallmark of successful weight control. We tested mediators of weight loss and weight loss maintenance in middle‐aged women who participated in a randomized controlled 12‐month weight management intervention. Overweight and obese women (N = 225, BMI = 31.3 ± 4.1 kg/m²) were randomly assigned to a control or a 1‐year group intervention designed to promote autonomous self‐regulation of body weight. Key exercise, eating behavior, and body image variables were assessed before and after the program, and tested as mediators of weight loss (12 months, 86% retention) and weight loss maintenance (24 months, 81% retention). Multiple mediation was employed and an intention‐to‐treat analysis conducted. Treatment effects were observed for all putative mediators (Effect size: 0.32–0.79, P < 0.01 vs. controls). Weight change was ?7.3 ± 5.9% (12‐month) and ?5.5 ± 5.0% (24‐month) in the intervention group and ?1.7 ± 5.0% and ?2.2 ± 7.5% in controls. Change in most psychosocial variables was associated with 12‐month weight change, but only flexible cognitive restraint (P < 0.01), disinhibition (P < 0.05), exercise self‐efficacy (P < 0.001), exercise intrinsic motivation (P < 0.01), and body dissatisfaction (P < 0.05) predicted 24‐month weight change. Lower emotional eating, increased flexible cognitive restraint, and fewer exercise barriers mediated 12‐month weight loss (R² = 0.31, P < 0.001; effect ratio: 0.37), but only flexible restraint and exercise self‐efficacy mediated 24‐month weight loss (R² = 0.17, P < 0.001; effect ratio: 0.89). This is the first study to evaluate self‐regulation mediators of weight loss and 2‐year weight loss maintenance, in a large sample of overweight women. Results show that lowering emotional eating and adopting a flexible dietary restraint pattern are critical for sustained weight loss. For long‐term success, interventions must also be effective in promoting exercise intrinsic motivation and self‐efficacy.     

Genetic influence on serum 25-hydroxyvitamin D concentration in Korean men: a cross-sectional study

Background

Hypovitaminosis D is prevalent worldwide. It is more prevalent in Eastern Asia region, including Korea. In addition to various environmental factors that influence serum 25-hydroxyvitamin D (25(OH)D) concentration, genetic influence also plays a significant role based on studies estimating the heritability of 25(OH)D in non-Asian populations. The objective of this study was to determine the genetic influence on serum 25(OH)D concentration in Korean men using the twin and family data.

Methods

A total of 1126 Korean male adult twins and family members from the Healthy Twin Study with serum 25(OH)D measurement were included in this cross-sectional study. Intraclass correlation coefficients (ICCs) and heritability were calculated by mixed linear regression analysis and quantitative genetic analysis after adjusting for environmental and lifestyle factors.

Results

Mean (±?standard deviation; SD) of serum 25(OH)D concentration was 15.34?±?6.18?ng/ml. The prevalence of vitamin D insufficiency was 19.8% and that of vitamin D deficiency was 77.9%. After adjusting for age, the highest ICC (0.61) was observed for monozygotic twin pairs while the lowest ICC (0.31) was found for father-son pairs. Age-adjusted heritability was estimated to be 58%. When physical activity, multivitamin intake and season of blood sampling were further considered, the ICC and heritability did not materially change. In the sensitivity analysis after excluding known multivitamin users, age-adjusted heritability was reduced to 44%.

Conclusions

In our study of Korean male twins and family members, heritability of 25(OH)D was moderately high. This supports the finding that genetic factors have significant influence on vitamin D status.

     

Contribution of genetic and environmental factors to variation in body compartments--a twin study in adults

This study aimed at analyzing the contribution of genetic and environmental factors on phenotypic variation of various traits of body composition. Subjects were 30 same-sexed pairs of twins including 20 monozygous (MZ) and 10 dizygous (DZ) pairs, aged 19-62 years. Zygosity was determined by DNA typing and morphological diagnosis. Body composition parameters (fat mass FM, lean body mass LBM, body cell mass BCM, extracellular mass ECM, total body water TBW, extracellular water ECW, and intracellular water ICW) were estimated by tetrapolar bioelectrical impedance analysis. Potential environmental factors influencing body composition (number of children, sporting activity and smoking behaviour) were determined by questionnaires. Heritabilities for traits of body composition were calculated by use of the twin method. Intraclass correlation is > 0.80 for the variation of LBM, BCM, ECM, TBW, ECW, and ICW in both MZ and DZ twins. Estimated heritability (h2) for FM, LBM, BCM, ECW, TBW, ECW, and ICW is 65%, 77%, 79%, 83%, 76%, 68%, and 82%, respectively. The h2 values for FM and LBM are consistent with those reported in other twin studies. For BCM, ECM, ECW and ICW, no comparative h2 estimates exist. Within-pair differences in body compartments do not change with increasing age in MZ and DZ twin pairs (p > 0.05). Stepwise multiple regression analyses indicate that zygosity, age, sex, number of children, sporting level and smoking behaviour do not significantly predict within-pair differences for weight, BMI, FM, LBM, TBW, ECW and ICW (each, p > 0.05). In contrast, sex and the number of children explain together 27% of observed within-pair differences for BCM. Zygosity is the only significant predictor of within-pair differences for ECM and height, explaining 20% (p = 0.008) and 36% of variance, respectively (p < 0.0001). Results indicate that genetic factors exert stronger influences on body composition than the considered environmental traits.     

Genetics of Callous-Unemotional Behavior in Children

Callous-unemotional behavior (CU) is currently under consideration as a subtyping index for conduct disorder diagnosis. Twin studies routinely estimate the heritability of CU as greater than 50%. It is now possible to estimate genetic influence using DNA alone from samples of unrelated individuals, not relying on the assumptions of the twin method. Here we use this new DNA method (implemented in a software package called Genome-wide Complex Trait Analysis, GCTA) for the first time to estimate genetic influence on CU. We also report the first genome-wide association (GWA) study of CU as a quantitative trait. We compare these DNA results to those from twin analyses using the same measure and the same community sample of 2,930 children rated by their teachers at ages 7, 9 and 12. GCTA estimates of heritability were near zero, even though twin analysis of CU in this sample confirmed the high heritability of CU reported in the literature, and even though GCTA estimates of heritability were substantial for cognitive and anthropological traits in this sample. No significant associations were found in GWA analysis, which, like GCTA, only detects additive effects of common DNA variants. The phrase ‘missing heritability’ was coined to refer to the gap between variance associated with DNA variants identified in GWA studies versus twin study heritability. However, GCTA heritability, not twin study heritability, is the ceiling for GWA studies because both GCTA and GWA are limited to the overall additive effects of common DNA variants, whereas twin studies are not. This GCTA ceiling is very low for CU in our study, despite its high twin study heritability estimate. The gap between GCTA and twin study heritabilities will make it challenging to identify genes responsible for the heritability of CU.     

Prevalence of Night Eating in Obese and Nonobese Twins

The aim of this study was to assess the prevalence of night eating (NE) and associated symptoms in a population‐based sample of Swedish twins. A total of 21,741 individuals aged 20–47 years completed a questionnaire in 2005/2006. NE was defined as ≥25% of daily food intake after the evening meal and/or awakening at least once per week with eating episodes. The prevalence of NE was 4.6% in men and 3.4% in women. Among obese men and women, the prevalence was 8.4 and 7.5%, respectively. Men and women with NE had 3.4 and 3.6 times higher risk of binge eating compared to individuals without NE. The risk of sleep‐related problems was 1.6–3.4 times higher in men and 2.5–3.3 times higher in women with NE compared to those without NE. This epidemiological study has estimated the prevalence of NE in a twin population. It revealed that NE is 2.5 and 2.8 times more common in obese men and women compared to normal weight men and women. Furthermore that NE is associated with binge eating and sleep‐related problems.     

Eating Frequency is Associated With Energy Intake but Not Obesity in Midlife Women

Midlife women tend to gain weight with age, thus increasing risk of chronic disease. The purpose of this study was to examine associations between overweight/obesity and behavioral factors, including eating frequency, in a cross‐sectional national sample of midlife women (n = 1,099) (mean age = 49.7 years, and BMI = 27.7 kg/m²). Eating behaviors and food and nutrient intakes were based on a mailed 1‐day food record. BMI was calculated from self‐reported height and weight, and level of physical activity was assessed by self‐reported questionnaire. After exclusion of low‐energy reporters (32% of sample), eating frequency was not associated with overweight/obesity (P > 0.05) and was not different between BMI groups (normal, 5.21 ± 1.79; overweight, 5.16 ± 1.74; obese, 5.12 ± 1.68, P = 0.769). Adjusted logistic regression showed that eating frequency, snacking frequency, breakfast consumption, eating after 10 pm and consuming meals with children or other adults were not significantly associated with overweight/obesity. Total energy intake increased as eating frequency increased in all BMI groups, however, obese women had greater energy intake compared to normal weight women who consumed the same number of meals and snacks. Intake of fruit and vegetables, whole grains, dietary fiber, dairy, and added sugars also increased as eating frequency increased. While eating frequency was not associated with overweight/obesity, it was associated with energy intake. Thus, addressing total energy intake rather than eating frequency may be more appropriate to prevent weight gain among midlife women.