Examining measurement invariance of appetitive trait and ARFID symptom measures by food security status.

OBJECTIVE: Measures assessing appetitive traits (i.e., individual differences in the desire to consume food) and disordered eating have generally been developed in predominantly food-secure populations. The current study aims to test measurement invariance (MI) for a measure of appetitive traits and a measure of Avoidant Restrictive Food Intake Disorder (ARFID) symptomology across food security status. METHOD: Data from a sample of mothers (n = 634) and two undergraduate samples (n = 945 and n = 442) were used to assess MI for the Adult Eating Behavior Questionnaire (AEBQ), which measures appetitive traits, and the Nine Item ARFID Screen (NIAS), which measures ARFID symptomology. Current food security was assessed using the 18-item USDA Household Food Security Survey Module, which was dichotomized into two groups: 1) the 'food insecure' group included marginal, low, and very low food security and 2) the 'food secure' group included high food security. Overall and multi-group confirmatory factor analyses were conducted separately for each measure in each sample. RESULTS: Results demonstrated scalar (i.e., strong) MI for both measures across samples, indicating that these measures performed equivalently across food-secure and food-insecure individuals. CONCLUSION: Findings suggest that differences in appetitive traits by food security status observed in prior research are not artifacts of measurement differences, but instead reflect true differences. Additionally, past mixed results regarding the relationship between food insecurity (FI) and ARFID symptomology are not likely driven by measurement error when using the NIAS.

Food insecurity is associated with eating disorders independent of depression and anxiety: Findings from the 2020-2021 Healthy Minds Study.

OBJECTIVE: To examine the association between food insecurity and eating disorder (ED) risk independent of co-occurring anxiety/depression. METHOD: Data were provided by 121,627 undergraduate/graduate students who participated in the 2020-2021 Healthy Minds Study (HMS). Participants responded to questionnaire measures of food insecurity and risk for EDs, depression, and anxiety. Established cut-offs were used to identify students with food insecurity and probable psychopathology. Separate modified Poisson regressions adjusted for age, gender, race/ethnicity, and socioeconomic background examined the association between food insecurity and each form of psychopathology. The association between food insecurity and probable ED was then examined in a regression further adjusted for probable depression and anxiety. RESULTS: Food insecurity was significantly associated with all three forms of psychopathology when examined separately (prevalence ratios ranged from 1.41 to 1.54, all p's < .001). When accounting for probable depression/anxiety, food insecurity was significantly associated with 1.19 times greater prevalence of a probable ED (p < .001). DISCUSSION: The association between food insecurity and EDs was replicated in a large, national sample of university students. To our knowledge, this is the first study to examine the independence of this relationship after adjusting for depression/anxiety. This finding supports the hypothesis that specific mechanisms, rather than general psychological distress, likely underlie the food insecurity-ED relationship.

Exploring the possibility of parents' broad internalizing phenotype acting through passive gene-environment correlations on daughters' disordered eating.

Twin studies demonstrate significant environmental influences and a lack of genetic effects on disordered eating before puberty in girls. However, genetic factors could act indirectly through passive gene-environment correlations (rGE; correlations between parents' genes and an environment shaped by those genes) that inflate environmental (but not genetic) estimates. The only study to explore passive rGE did not find significant effects, but the full range of parental phenotypes (e.g., internalizing symptoms) that could impact daughters' disordered eating was not examined. We addressed this gap by exploring whether parents' internalizing symptoms (e.g., anxiety, depressive symptoms) contribute to daughters' eating pathology through passive rGE. Participants were female twin pairs (aged 8-14 years; M = 10.44) in pre-early puberty and their biological parents (n = 279 families) from the Michigan State University Twin Registry. Nuclear twin family models explored passive rGE for parents' internalizing traits/symptoms and twins' overall eating disorder symptoms. No evidence for passive rGE was found. Instead, environmental factors that create similarities between co-twins (but not with their parents) and unique environmental factors were important. In pre-early puberty, genetic factors do not influence daughters' disordered eating, even indirectly through passive rGE. Future research should explore sibling-specific and unique environmental factors during this critical developmental period.

Exploring differential item functioning on eating disorder measures by food security status.

PURPOSE: Food insecurity is associated with elevated eating disorder (ED) pathology, yet commonly used ED measures may not fully capture ED pathology in the context of food insecurity. The present study used differential item functioning (DIF) analyses to explore whether item endorsement on two commonly used ED questionnaires differed by food security status. METHODS: Participants were 634 cisgender women recruited through Amazon's Mechanical Turk. DIF was explored for items on the Short Eating Disorder Examination Questionnaire (S-EDE-Q) and the Eating Disorder Diagnostic Scale for DSM-5 (EDDS-5). DIF analyses used a hybrid ordinal logistic regression/item response theory approach, with the presence of both statistical (p < .01) and clinical significance (pseudo ΔR2 ≥ .035) indicating DIF. RESULTS: There was no evidence of clinically significant DIF within the S-EDE-Q. Two items on the EDDS-5 exhibited statistically and clinically significant DIF, with moderate effect sizes. Specifically, compared to food-secure participants, food-insecure participants were more likely to report (1) eating large amounts of food when not physically hungry and (2) feeling disgusted, depressed, or guilty about overeating at lower levels of overall ED pathology but less likely to report these experiences at higher levels of overall ED pathology. CONCLUSIONS: Findings highlight a potential need to adapt ED measures to fully capture ED pathology in food-insecure populations. LEVEL OF EVIDENCE: Level III, well-designed cohort study.

Bi-Directional Associations Between Real-Time Affect and Physical Activity in Weight-Discordant Siblings.

Pediatric obesity confers increased risk for a host of negative psychological and physical health consequences and is reliably linked to low levels of physical activity. Affective antecedents and consequences of physical activity are thought to be important for the development and maintenance of such behavior, though research examining these associations in youth across the weight spectrum remains limited. OBJECTIVE: This study examined bi-directional associations between affect and physical activity (i.e., moderate-to-vigorous physical activity [MVPA] and total activity counts), and the extent to which weight (body mass index z-score [z-BMI]) moderated these associations. METHODS: Participants were drawn from a prior study of siblings (N = 77; mean age = 15.4 ± 1.4 years) discordant for weight status (39 nonoverweight siblings, 38 siblings with overweight/obesity) who completed ecological momentary assessment (EMA) with accelerometer-assessed physical activity. RESULTS: Generalized linear mixed models indicated z-BMI moderated trait-level and momentary associations. When adolescents with higher z-BMI reported momentary negative affect, they evidenced less MVPA within the next hour. Across the sample, greater overall activity was associated with lower negative affect. However, at the momentary level, when adolescents with higher (but not lower) z-BMI evidenced greater activity, they reported decreases in negative affect. CONCLUSIONS: Findings indicate affective experiences surrounding physical activity differ according to z-BMI. Specifically, momentary negative affect may impede momentary MVPA among youth with higher z-BMI. Further research is warranted to elucidate factors influencing these momentary associations and the extent to which these momentary associations prospectively predict weight change.

Examining vegetarianism, weight motivations, and eating disorder psychopathology among college students.

OBJECTIVE: Previous research has suggested a link between vegetarianism, broadly defined, and symptoms of eating disorders (ED). However, the literature supporting this link is mixed and limited by possible measurement artifacts. Using data from a national sample of college students, the present study examines ED symptomatology among three groups: (a) vegetarians whose meat avoidance is motivated by weight concerns; (b) non-weight motivated vegetarians; and (c) nonvegetarians. METHOD: Participants include 9,910 students from 12 colleges and universities across the United States who participated in the web-based Healthy Bodies Study. ED symptomatology was measured using the Short-Eating Disorder Examination-Questionnaire (S-EDE-Q). First, multi-group confirmatory factor analysis was conducted to test measurement invariance (MI) of the S-EDE-Q across weight-motivated vegetarians, non-weight-motivated vegetarians, and nonvegetarians. Gender- and BMI-adjusted ANCOVA was used to compare S-EDE-Q scores across groups. RESULTS: 9.3% of participants were vegetarian. Cis-women and gender minority students were more likely to be vegetarian; those who became vegetarians after entering college were more likely to report weight-related motivations. Strict MI was supported for the S-EDE-Q global and subscale scores. Weight-motivated vegetarians reported higher levels of restraint, shape/weight overvaluation, body dissatisfaction, and global ED psychopathology relative to other participants. DISCUSSION: To our knowledge, this is the first to explicitly link weight motivations for vegetarianism to ED psychopathology in a large, representative sample of young adults. Results suggest that students presenting with ED symptoms should be assessed for their motivations for adopting a vegetarian diet, and this information should be considered in treatment decisions.

Gender-based differential item functioning in measures of eating pathology.

OBJECTIVE: Eating disorder (ED) symptoms are common and impairing in males, despite their perception as "female" disorders. As existing self-report symptom measures were developed and primarily validated in women, there is a need to establish the utility of these measures in men. The present study used differential item functioning (DIF) analyses to explore whether item endorsement differed by gender for three commonly used ED symptom measures. METHOD: Participants were undergraduate men (n = 1,083) and women (n = 2,424) from three universities in the United States. Global scores on the Eating Attitudes Test-26 (EAT-26), Eating Disorder Examination Questionnaire (EDEQ), and Eating Disorder Diagnostic Scale for DSM-IV (EDDS) were examined. Tests of DIF were conducted by regressing each item against its composite scale score, and then comparing fit and variance explained (R2 ) to a model with the interaction of item*gender. The clinical significance threshold for DIF is ΔR2 ≥ 0.13. RESULTS: There was no evidence of clinically significant DIF within the EAT-26, EDEQ, or EDDS. DISCUSSION: Findings suggest that the examined measures perform similarly for undergraduate men and women, supporting their use in nonclinical male samples. However, development and testing of items reflecting ED symptoms that more commonly occur in males (e.g., muscularity-oriented behaviors) is encouraged.

Genetic and environmental associations between body dissatisfaction, weight preoccupation, and binge eating: Evidence for a common factor with differential loadings across symptom type.

OBJECTIVE: Prior twin studies provide support for a single "common factor" that contributes genetic and environmental risk to a range of disordered eating symptoms. However, the common factor may be indexed less well by binge eating (BE) than other symptoms of eating disorders [i.e., body dissatisfaction (BD) and weight preoccupation (WP)]. We sought to explore the presence of a common factor and test whether loadings differed across three key symptoms (i.e., BE, BD, WP). METHOD: Disordered eating was assessed via self-report in 631 female twin pairs from the Michigan State University Twin Registry. RESULTS: We detected a common disordered eating factor that was influenced primarily by additive genetic and nonshared environmental influences. However, we observed different loadings on this common factor by symptom type, as factor loadings for BD and WP were stronger than that for BE. Moreover, the residual environmental and/or genetic variances (i.e., those that are independent of the common factor) were larger in BE than those of BD or WP. DISCUSSION: Although all three symptoms share a common set of genetic and environmental influences, risk for BE may involve additional genetic, biological, and environmental factors that are not shared with other symptoms of eating pathology. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:157-161).

Does parental divorce moderate the heritability of body dissatisfaction? An extension of previous gene-environment interaction effects.

OBJECTIVE: Previous research suggests that parental divorce moderates genetic influences on body dissatisfaction. Specifically, the heritability of body dissatisfaction is higher in children of divorced versus intact families, suggesting possible gene-environment interaction effects. However, prior research is limited to a single, self-reported measure of body dissatisfaction. The primary aim of this study was to examine whether these findings extend to a different dimension of body dissatisfaction: body image perceptions. METHOD: Participants were 1,534 female twins from the Minnesota Twin Family Study, aged 16-20 years. The Body Rating Scale (BRS) was used to assess body image perceptions. RESULTS: Although BRS scores were heritable in twins from divorced and intact families, the heritability estimates in the divorced group were not significantly greater than estimates in the intact group. However, there were differences in nonshared environmental effects, where the magnitude of these environmental influences was larger in the divorced as compared with the intact families. DISCUSSION: Different dimensions of body dissatisfaction (i.e., negative self-evaluation versus body image perceptions) may interact with environmental risk, such as parental divorce, in discrete ways. Future research should examine this possibility and explore differential gene-environment interactions using diverse measures.

The role of stress in the association among food insecurity, eating disorder pathology, and binge eating-related appetitive traits.

PURPOSE: Growing literature demonstrates a positive association between food insecurity (FI) and eating disorder pathology. Additionally, FI has been associated with two appetitive traits strongly linked to binge eating, food responsiveness and emotional overeating. However, little research has investigated factors that might help to explain these associations. One hypothesis is that experiencing FI may increase stress, and that eating disorder pathology, particularly binge eating-related phenotypes, may serve as a coping strategy. This study explores stress as a potential mechanism in the association between FI and general eating disorder pathology, as well as two appetitive traits strongly associated with binge eating (food responsiveness and emotional overeating). METHODS: Cis-gender women (N = 634) completed online questionnaires assessing FI, stress, eating disorder pathology (measured via the total score on the Short Eating Disorder Examination Questionnaire), and binge eating-related appetitive traits (measured via the Adult Eating Behavior Questionnaire). Cross-sectional indirect effects analyses with a 1000-sample bootstrap were used to test pathways among FI, stress, and eating-related constructs. RESULTS: FI was significantly associated with eating disorder pathology and associated appetitive traits (ps < 0.001). Stress explained a significant proportion of the correlation between FI and each eating-related construct. CONCLUSIONS: Our findings extend prior research on the relationships between FI, eating disorder pathology, and binge eating-related appetitive traits to provide preliminary evidence that stress may act as an underlying mechanism. Future studies should use longitudinal designs to assess the prospective relationships among these constructs.

Exploring differences in disordered eating and related appetitive traits among women based on childhood and current food security status.

Despite emerging evidence that food insecurity (FI) is associated with elevated rates of eating pathology, little is known about the lasting impact of FI on eating behaviors. Studies that have explored the association between FI during childhood and eating behavior in adulthood have not accounted for current FI. The present study explored differences in disordered eating (DE) and related appetitive traits among four groups of cisgender female mothers: individuals who (1) endorsed childhood FI only (n = 96), (2) endorsed current FI only (n = 134), (3) endorsed both childhood and current FI (n = 257), and (4) denied both childhood and current FI (n = 146). Participants responded to online questionnaires including items from the USDA Household Food Security Survey Module, the 7-item Eating Disorder Examination-Questionnaire, the Eating Disorder Diagnostic Scale, and the Adult Eating Behavior Questionnaire. Adjusting for age and race/ethnicity, ANCOVAs explored mean differences between groups in DE and appetitive traits, and a modified Poisson regression model examined differences in binge-eating prevalence across the four FI groups. The "current FI only" group consistently endorsed the highest levels of DE and related appetitive traits followed by the "current and childhood FI" group, suggesting newly food-insecure women may be at highest risk for DE. Interestingly, across almost all constructs, the "childhood FI only" group did not differ significantly from the "no FI" group. These findings suggest that improved access to food may help offset risk for adult DE related to experiences of FI in childhood.

Disadvantage and disordered eating in boys: Examining phenotypic and genotype × environment associations across development.

Socioeconomic disadvantage may be a significant risk factor for disordered eating, particularly for individuals with underlying genetic risk. However, little to nothing is known about the impact of disadvantage on disordered eating in boys during the critical developmental risk period. Crucially, risk models developed for girls may not necessarily apply to boys, as boys show different developmental patterns of disordered eating risk (i.e., earlier activation of genetic influences during adrenarche, an early stage of puberty). This is the first study to examine phenotypic and Genotype × Environment (G × E) effects of disadvantage in boys. Analyses examined 3,484 male twins ages 8-17 (Mage = 12.27, SD = 2.96) from the Michigan State University Twin Registry. Disordered eating (e.g., body dissatisfaction, binge eating) was measured using the parent-report Michigan Twins Project Eating Disorder Survey. Neighborhood disadvantage was measured using a census-tract level Area Deprivation Index, and family socioeconomic status was determined from parental income and education. Adrenarche status was determined using multiple indicators, including age and Pubertal Development Scale scores. G × E models suggested that genetic influences on disordered eating were activated earlier for boys experiencing familial or neighborhood disadvantage, with substantial genetic influences in early adrenarche, when genetic influences were low in more advantaged boys. Phenotypically, both neighborhood and familial disadvantage were associated with greater disordered eating for boys in late adrenarche, which could indicate a lasting impact of earlier activation of genetic influences on later risk. Results highlight disadvantage as a novel risk factor for disordered eating in boys, particularly those with genetic vulnerabilities. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Genetic and environmental influences on thin-ideal internalization.

OBJECTIVE: Current research on the etiology of thin-ideal internalization focuses on psychosocial influences (e.g., media exposure). The possibility that genetic influences also account for variance in thin-ideal internalization has never been directly examined. This study used a twin design to estimate genetic effects on thin-ideal internalization and examine if environmental influences are primarily shared or nonshared in origin. METHOD: Participants were 343 postpubertal female twins (ages: 12-22 years; M = 17.61) from the Michigan State University Twin Registry. Thin-ideal internalization was assessed using the Sociocultural Attitudes toward Appearance Questionnaire-3. RESULTS: Twin modeling suggested significant additive genetic and nonshared environmental influences on thin-ideal internalization. Shared environmental influences were small and non-significant. DISCUSSION: Although prior research focused on psychosocial factors, genetic influences on thin-ideal internalization were significant and moderate in magnitude. Research is needed to investigate possible interplay between genetic and nonshared environmental factors in the development of thin-ideal internalization.

The effects of puberty and ovarian hormone removal on developmental trajectories of palatable food and chow intake in female rats.

OBJECTIVE: Palatable food (PF) intake is significantly greater in females than males and increases during adolescence. Previous data suggest that puberty and ovarian hormones may contribute to these sex and developmental differences, but few studies have examined this possibility. The aim of the current study was to address these gaps by examining trajectories of PF and chow intake during pre-puberty, puberty, and adulthood in intact female rats (Study 1) as well as in those receiving pre-pubertal ovariectomies (P-OVX) (Study 2). METHOD: We examined our study aims using archival data from 66 intact Sprague-Dawley female rats (Study 1) and 77 P-OVX and 79 intact Sprague-Dawley female rats (Study 2). PF and chow intake were measured using a free-choice, intermittent exposure paradigm in which rats were exposed to both food types starting in pre-puberty and continuing into adulthood. RESULTS: Mixed linear models revealed a specific effect of puberty on PF intake in both studies. PF intake increased substantially during puberty in all rats, but increases were particularly pronounced in P-OVX rats in Study 2. By contrast, chow intake increased significantly during pre-puberty (rather than puberty) in both studies, and these increases were relatively unaffected by P-OVX. DISCUSSION: Findings confirm a specific effect of puberty and ovarian hormone removal on PF intake in female rats. Differential trajectories of PF versus chow intake highlight potential reward-based processes in pubertal and ovarian hormone effects on PF intake in females.

Associations between objective physical activity and emotional eating among adiposity-discordant siblings using ecological momentary assessment and accelerometers.

BACKGROUND: Emotional eating is associated with obesity, though less is known regarding factors that predict emotional eating episodes in children and adolescents. OBJECTIVES: To investigate whether moderate to vigorous physical activity (MVPA) or total activity counts 60 minutes prior to psychological stress predicted stress-related eating and positive emotional eating (ie, eating while happy), and whether adiposity (z-BMI) moderated these associations. METHODS: Participants were drawn from a prior study of siblings (N = 77; mean age = 15.4 ± 1.4 years) discordant for weight status (39 non-overweight siblings, 38 siblings with overweight/obesity) who completed an ecological momentary assessment protocol with accelerometer-based assessment of physical activity. RESULTS: Greater MVPA was associated with lower stress-related eating across the sample. Lower total activity (between-person effects) and lower MVPA (within-person effects) were associated with greater stress-related eating for siblings with greater z-BMI. Greater total activity was associated with lower positive emotional eating for siblings with lower z-BMI (between- and within-person). CONCLUSIONS: Findings demonstrate potential regulating effects of prior physical activity on emotional eating at the individual and momentary level, though there are nuances depending on z-BMI. Future work is needed to examine underlying mechanisms and timescale of effects, and particularly the extent to which enhancing MVPA time among youth with z-BMI may mitigate momentary risk of stress-related eating episodes.

Differences in genetic and environmental influences on body weight and shape concerns across pubertal development in females.

The heritability of disordered eating increases during puberty; however, prior studies have largely examined a composite score of disordered eating, rather than specific symptoms. Body weight and shape concerns cut across all eating disorder diagnoses and are some of the strongest prospective risk factors for the development of eating disorders. Yet, little is known about potential developmental increases or decreases in genetic and environmental influences for these key symptoms. This study examined differences in genetic and environmental effects on a range of body weight and shape concerns during puberty and compared results to findings for overall levels of disordered eating symptoms. Participants were 926 same-sex female twins (ages 8-16) from the Michigan State University Twin Registry. Well-validated questionnaires were used to examine pubertal maturation, overall levels of disordered eating, and a range of cognitive body weight/shape constructs: body dissatisfaction, weight/shape concerns, and weight preoccupation. Findings for overall levels of disordered eating were very similar to those obtained in previous work, with significantly increased genetic effects in girls at more advanced pubertal development. Importantly, these same pubertal increases in genetic influences were observed for body dissatisfaction and weight/shape concerns. However, no pubertal moderation of genetic effects was observed for weight preoccupation; instead, pubertal moderation of nonshared and shared environmental effects was observed. Our findings point to differences in the extent to which genetic and environmental factors contribute to various cognitive body weight and shape symptoms during puberty.

Elucidating factors underlying parent-offspring similarity in eating pathology in pre- and early puberty: Exploring the possibility of passive gene-environment correlation.

Familial resemblance in eating pathology is typically attributed to parents providing an environment that leads to the development of eating pathology. However, offspring raised by biological parents receive both their environment and genes from their parents, raising the possibility that genetic influences, environmental influences, and/or gene-environment interplay may account for familial resemblance. Past studies have not explored the possibility of parents' genes influencing the environment they provide (i.e., passive gene-environment correlations or "passive rGE"). If present, passive rGE is most likely to "hide" in estimates of shared environmental influence in classical twin models. The current study used a nuclear twin family design to explore the possibility of passive rGE during pre- and early puberty when past studies have demonstrated the importance of shared environmental influence. Additionally, the present study explored whether sibling-specific (i.e., influences specific to the twin generation) or family-specific (i.e., "cultural" influences within the home) environmental influences account for shared environmental influences found in past studies. Participants included preearly pubertal same-sex female twins and their biological parents (N = 547 families) from the Minnesota Twin Family Study and the Michigan State University Twin Registry. Disordered eating was assessed with self-report measures in the twins and parents. Pubertal status was determined using an established cut-off on a self-report measure. Passive rGE was not indicated in this study of pre- and early pubertal twins. Instead, sibling-specific shared environmental and nonshared environmental influences were most influential. Future research should work to identify the sibling-specific environmental influences that contribute to sibling similarity in disordered eating. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Socialization and selection effects in the association between weight conscious peer groups and thin-ideal internalization: A co-twin control study.

Affiliation with weight conscious peer groups is theorized to increase thin-ideal internalization through socialization processes. However, selection effects could contribute if genetic and/or environmental predispositions lead to affiliation with weight conscious peers. Co-twin control methodology was used to examine socialization and selection effects in 614 female twins (ages 8-15) from the Michigan State University Twin Registry (MSUTR). Thin-ideal internalization and peer group characteristics were assessed via self-report questionnaires. Results suggested the presence of both socialization and selection effects. In terms of socialization, twins who reported increased exposure to weight conscious peers relative to their co-twins had elevated thin-ideal internalization scores, regardless of zygosity. However, associations between weight conscious peers and thin-ideal internationalization within twin pairs were attenuated, suggesting that genetic and shared environmental selection effects also contribute. Findings significantly extend previous work by confirming the presence of socialization processes and highlighting selection processes to be examined in future longitudinal research.

What drives the association between weight-conscious peer groups and disordered eating? Disentangling genetic and environmental selection from pure socialization effects.

Previous studies suggest strong associations between exposure to weight-conscious peer groups and increased levels of disordered eating. This association has been attributed to socialization effects (i.e., membership leads to disordered eating); however, selection effects (i.e., selecting into peer groups based on genetic and/or environmental predispositions toward disordered eating) could contribute to or even account for these associations. The current study was the first to use a co-twin control design to disentangle these types of selection factors from socialization effects. Participants included 610 female twins (ages 8-14) drawn from the Michigan State University Twin Registry. To comprehensively examine a range of eating pathology, several disordered eating attitudes and behaviors (e.g., body dissatisfaction, binge eating) were examined via self-report questionnaires. Questionnaires also were used to assess peer group emphasis on body weight and shape. Replicating previous results, significant individual-level associations were found between membership in weight-conscious peer groups and disordered eating. However, co-twin control analyses indicated that these associations were largely due to genetic and/or shared environmental selection factors rather than pure socialization effects. Importantly, results remained unchanged when controlling for pubertal status, suggesting that effects do not vary across developmental stage. Overall, these findings question whether associations between weight-conscious peer groups and disordered eating are due entirely to socialization processes. Future studies are needed to identify the specific genetic and/or shared environmental factors that may drive selection into weight-conscious peer groups.

Differential Effects of Estrogen and Progesterone on Genetic and Environmental Risk for Emotional Eating in Women.

Recent data show shifts in genetic and environmental influences on emotional eating across the menstrual cycle, with significant shared environmental influences during pre-ovulation, and primarily genetic effects during post-ovulation. Factors driving differential effects are unknown, although increased estradiol during pre-ovulation and increased progesterone during post-ovulation are thought to play a role. We indirectly investigated this possibility by examining whether overall levels of estradiol and progesterone differentially impact genetic and environmental risk for emotional eating in adult female twins (N = 571) drawn from the MSU Twin Registry. Emotional eating, estradiol levels, and progesterone levels were assessed daily and then averaged to create aggregate measures for analysis. As predicted, shared environmental influences were significantly greater in twins with high estradiol levels, whereas additive genetic effects increased substantially across low versus high progesterone groups. Results highlight significant and differential effects of ovarian hormones on etiologic risk for emotional eating in adulthood.