First Course

Kevin Lewis

December 23, 2012

The critical period of infant feeding for the development of early disparities in obesity

Amanda Thompson & Margaret Bentley
Social Science & Medicine, forthcoming

Childhood obesity is an increasing public health problem, particularly among minority infants and young children. Disparities in overweight prevalence persist and widen with age, highlighting the need to identify factors contributing to early excess weight gain. We review the behavioral, social and macro-environmental factors contributing to the development of obesogenic early feeding practices among African-American infants and young children. We then examine the sociodemographic, household factors, feeding beliefs and infant characteristics associated with age-inappropriate feeding of liquids and solids (inappropriate feeding) among mothers and infants participating the U.S. Infant Care and Risk of Obesity Study, a cohort study of 217 low-income, first-time mothers and infants followed from 3-18 months of age. Maternal and infant anthropometry, infant diet, and maternal and household characteristics were collected at home visits at 3, 6, 9, 12 and 18 months of age. Mixed logistic regression was used to estimate the association between maternal and infant characteristics and inappropriate feeding. Rates of age-inappropriate feeding are high; over 75% of infants received solids or juice by 3 months of age. The odds of age-inappropriate feeding were higher among mothers who were single, depressed or believed that their infant is a "greedy" baby. Inappropriate feeding was associated with higher daily energy intake in infants (β=109.28 calories, p=0.01) and with increased odds of high infant weight-for-length (WFL; OR= 1.74, 95%CI: 1.01-3.01). Our findings suggest that age-inappropriate complementary feeding influences current energy intakes and infant WFL factors that may increase long-term obesity risk by shaping infant appetite, food preferences, and metabolism. Given the intractability of pediatric obesity, understanding the role of early feeding in shaping long-term health disparities is critical for developing prevention strategies to stem obesity in early childhood.


Maternal Prepregnancy BMI and Child Cognition: A Longitudinal Cohort Study

Emre Basatemur et al.
Pediatrics, forthcoming

Objective: To examine the association between maternal prepregnancy BMI and cognitive performance in children at 5 and 7 years of age.

Methods: This is a secondary analysis of data from the Millennium Cohort Study, a prospective population based cohort of 19 517 children in the United Kingdom. Standardized cognitive assessments of children, involving components of the British Ability Scales, second edition and a number skills test, were performed at 5 and 7 years of age. Principal components analysis was used to identify a general cognitive ability factor (g) from individual test scores. Maternal prepregnancy BMI was retrospectively self-reported when children were 9 months old. Mixed-effects linear regression models were fitted, controlling for multiple socio-demographic factors, child's birth weight, child's BMI, maternal smoking, and maternal diabetes. Complete data were available for 11 025 children at 5 years, and 9882 children at 7 years.

Results: Maternal prepregnancy BMI was negatively associated with children's cognitive performance (g) at age 5 (P = .0069) and age 7 (P < .0001). The overall effect size was modest: a 10-point increase in maternal BMI was associated with a decrease in cognitive performance of ∼1/10th of an SD at age 7.

Conclusions: Maternal prepregnancy BMI is negatively associated with children's cognitive performance, even after adjusting for multiple socio-demographic confounders and children's BMI. The relationship appears to become stronger as children get older, although the overall effect size is modest. In utero fetal programming or residual confounding may explain these findings.


The Relation of Adiposity to Cognitive Control and Scholastic Achievement in Preadolescent Children

Keita Kamijo et al.
Obesity, December 2012, Pages 2406-2411

Adiposity may be negatively associated with cognitive function in children. However, the findings remain controversial, in part due to the multifaceted nature of cognition and perhaps the lack of accurate assessment of adiposity. The aim of this study was to clarify the relation of weight status to cognition in preadolescent children using a comprehensive assessment of cognitive control, academic achievement, and measures of adiposity. Preadolescent children between 7 and 9 years (n = 126) completed Go and NoGo tasks, as well as the Wide Range Achievement Test 3rd edition (WRAT3), which measures achievement in reading, spelling, and arithmetic. In addition to BMI, fat mass was measured using dual-energy X-ray absorptiometry (DXA). Data were analyzed with multiple regression analysis, controlling for confounding variables. Analyses revealed that BMI and fat mass measured via DXA were negatively associated with cognitive control, as children with higher BMI and fat mass exhibited poorer performance on the NoGo task requiring extensive amounts of inhibitory control. By contrast, no relation of weight status to performance was observed for the Go task requiring smaller amounts of cognitive control. Higher BMI and fat mass were also associated with lower academic achievement scores assessed on the WRAT3. These data suggest that adiposity is negatively and selectively associated with cognitive control in preadolescent children. Given that cognitive control has been implicated in academic achievement, the present study provides an empirical basis for the negative relationship between adiposity and scholastic performance.


Episodic Memory and Appetite Regulation in Humans

Jeffrey Brunstrom et al.
PLoS ONE, December 2012

Psychological and neurobiological evidence implicates hippocampal-dependent memory processes in the control of hunger and food intake. In humans, these have been revealed in the hyperphagia that is associated with amnesia. However, it remains unclear whether ‘memory for recent eating' plays a significant role in neurologically intact humans. In this study we isolated the extent to which memory for a recently consumed meal influences hunger and fullness over a three-hour period. Before lunch, half of our volunteers were shown 300 ml of soup and half were shown 500 ml. Orthogonal to this, half consumed 300 ml and half consumed 500 ml. This process yielded four separate groups (25 volunteers in each). Independent manipulation of the ‘actual' and ‘perceived' soup portion was achieved using a computer-controlled peristaltic pump. This was designed to either refill or draw soup from a soup bowl in a covert manner. Immediately after lunch, self-reported hunger was influenced by the actual and not the perceived amount of soup consumed. However, two and three hours after meal termination this pattern was reversed - hunger was predicted by the perceived amount and not the actual amount. Participants who thought they had consumed the larger 500-ml portion reported significantly less hunger. This was also associated with an increase in the ‘expected satiation' of the soup 24-hours later. For the first time, this manipulation exposes the independent and important contribution of memory processes to satiety. Opportunities exist to capitalise on this finding to reduce energy intake in humans.


Impact of Information About Obesity Genomics on the Stigmatization of Overweight Individuals: An Experimental Study

Natalie Lippa & Saskia Sanderson
Obesity, December 2012, Pages 2367-2376

Advances in genomic technologies are rapidly leading to new understandings of the roles that genetic variations play in obesity. Increasing public dissemination of information regarding the role of genetics in obesity could have beneficial, harmful, or neutral effects on the stigmatization of obese individuals. This study used an online survey and experimental design to examine the impact of genetic versus non-genetic information on obesity stigma among self-perceived non-overweight individuals. Participants (n = 396) were randomly assigned to read either genetic, non-genetic (environment), or gene-environment interaction obesity causal information. A total of 48% of participants were female; mean age was 42.7 years (range = 18-86 years); 75% were white; 45.2% had an annual household income of less than $40,000; mean BMI was 23.4 kg/m2. Obesity stigma was measured using the Fat Phobia Scale - short form (FPS-S). After reading the experimental information, participants in the genetic and gene-environment conditions were more likely to believe that genetics increase obesity risk than participants in the non-genetic condition (both P < 0.05), but did not differ on obesity stigma. Obesity stigma was higher among whites and Asians than Hispanics and African Americans (P = 0.029), and associated with low self-esteem (P = 0.036). Obesity stigma was also negatively associated with holding 'germ or virus' (P = 0.033) and 'overwork' (P = 0.016) causal beliefs about obesity, and positively associated with 'diet or eating habits' (P = 0.001) and 'lack of exercise' (P = 0.004) causal beliefs. Dissemination of brief information about the role of genetics in obesity may have neither a beneficial nor a harmful impact on obesity stigmatization compared with non-genetic information among self-perceived non-overweight individuals.


Hypothesis: Bacteria control host appetites

Vic Norris, Franck Molina & Andrew Gewirtz
Journal of Bacteriology, forthcoming

To help investigate the relationship between inflammatory and other diseases and the composition of the gut microbiota, we propose that a positive feedback loop exists between the preferences of the host for a particular dietary regime, the composition of the gut microbiota that depends on this regime, and the preferences of the host as influenced by the gut microbiota. We cite evidence in support of this hypothesis and make testable predictions.


Are increased weight and appetite useful indicators of depression in children and adolescents?

David Cole et al.
Journal of Abnormal Psychology, November 2012, Pages 838-851

During childhood and adolescence, physiological, psychological, and behavioral processes strongly promote weight gain and increased appetite while also inhibiting weight loss and decreased appetite. The Diagnostic and Statistical Manual-IV (DSM-IV) treats both weight-gain/increased-appetite and weight-loss/decreased-appetite as symptoms of major depression during these developmental periods, despite the fact that one complements typical development and the other opposes it. To disentangle the developmental versus pathological correlates of weight and appetite disturbance in younger age groups, the current study examined symptoms of depression in an aggregated sample of 2307 children and adolescents, 47.25% of whom met criteria for major depressive disorder. A multigroup, multidimensional item response theory model generated three key results. First, weight loss and decreased appetite loaded strongly onto a general depression dimension; in contrast, weight gain and increased appetite did not. Instead, weight gain and increased appetite loaded onto a separate dimension that did not correlate strongly with general depression. Second, inclusion or exclusion of weight gain and increased appetite affected neither the nature of the general depression dimension nor the fidelity of major depressive disorder diagnosis. Third, the general depression dimension and the weight-gain/increased-appetite dimension showed different patterns across age and gender. In child and adolescent populations, these results call into question the utility of weight gain and increased appetite as indicators of depression. This has serious implications for the diagnostic criteria of depression in children and adolescents. These findings inform a revision of the DSM, with implications for the diagnosis of depression in this age group and for research on depression.


Association of Nutrient-Dense Snack Combinations With Calories and Vegetable Intake

Brian Wansink, Mitsuru Shimizu & Adam Brumberg
Pediatrics, forthcoming

Background: With other factors such as general diet and insufficient exercise, eating non-nutrient dense snack foods such as potato chips contributes to childhood obesity. We examined whether children consumed fewer calories when offered high-nutrient dense snacks consisting of cheese and vegetables than children who were offered non-nutrient dense snacks (ie, potato chips).

Methods: Two hundred one children (115 girls) entering the third to sixth grades were randomly assigned to 1 of 4 snacking conditions: (1) potato chips only, (2) cheese-only, (3) vegetables only, and (4) cheese and vegetables. Children were allowed to eat snacks freely provided while watching 45-minute TV programs. Satiety was measured before they started eating snacks, in the middle of the study, and 20 minutes after they finished eating the snacks. Parents completed a questionnaire regarding their family environment.

Results: Children consumed 72% fewer calories when eating a combined snack compared with when they were served potato chips, P < .001. Children who ate the combination snack needed significantly fewer calories to achieve satiety than those who ate potato chips, P < .001. The effects of the snack conditions on caloric intake were more pronounced among overweight or obese children (P = .02) and those from low-involvement families (P = .049)

Conclusions: The combination snack of vegetables and cheese can be an effective means for children to reduce caloric intake while snacking. The effect was more pronounced among children who were overweight or obese and children from low-involvement families.


Preschool children with lower executive function may be more vulnerable to emotional-based eating in the absence of hunger

Joy Rickman Pieper & Kevin Laugero
Appetite, forthcoming

Decreased executive function (EF) has been linked to unhealthy eating behaviors and obesity in older children and adults, however little is known about this relationship in young children. One possible reason for this association is that individuals with degraded EF are more vulnerable to emotional-based overeating. Emotional eating may thus be more likely to occur in persons with lower self-control or ability to regulate emotions. A pilot project in a research-based preschool was conducted to examine the relationships between executive function, emotional arousal and eating in the absence of hunger (EAH) in three to six year-old children. Executive function was measured through child-completed tasks, parent questionnaires, and standardized teacher reports. Emotional arousal was measured via skin conductance. Children who had lower cognitive development scores as indicated by teacher reports had higher EAH. Increased emotional arousal was associated with increased EAH, but only in a subgroup of children who had a lower capacity for emotional regulation as suggested by lower delay of gratification scores, lower effortful control (parent questionnaire), and overall lower teacher-reported cognitive development. Further studies are necessary to determine whether interventions to improve executive function and emotional regulation in young children may also have the benefit of improving eating behaviors and decreasing risk of obesity in the long run.


Association of personality with the development and persistence of obesity: A meta-analysis based on individual-participant data

M. Jokela et al.
Obesity Reviews, forthcoming

Personality is thought to affect obesity risk but before such information can be incorporated into prevention and intervention plans, robust and converging evidence concerning the most relevant personality traits is needed. We performed a meta-analysis based on individual-participant data from nine cohort studies to examine whether broad-level personality traits predict the development and persistence of obesity (n = 78,931 men and women; mean age 50 years). Personality was assessed using inventories of the Five-Factor Model (extraversion, neuroticism, agreeableness, conscientiousness and openness to experience). High conscientiousness - reflecting high self-control, orderliness and adherence to social norms - was associated with lower obesity risk across studies (pooled odds ratio [OR] = 0.84; 95% confidence interval [CI] = 0.80-0.88 per 1 standard deviation increment in conscientiousness). Over a mean follow-up of 5.4 years, conscientiousness predicted lower obesity risk in initially non-obese individuals (OR = 0.88, 95% CI = 0.85-0.92; n = 33,981) and was associated with greater likelihood of reversion to non-obese among initially obese individuals (OR = 1.08, 95% CI = 1.01-1.14; n = 9,657). Other personality traits were not associated with obesity in the pooled analysis, and there was substantial heterogeneity in the associations between studies. The findings indicate that conscientiousness may be the only broad-level personality trait of the Five-Factor Model that is consistently associated with obesity across populations.


Using subtle reminders of love to foster healthy snack choices

David Raska & Bridget Nichols
Journal of Consumer Behaviour, November/December 2012, Pages 432-442

Employing three experiments with US college students, we examined how subtle reminders of companionate and sexual love affect consumers' healthy snack choices. Two different symbols of companionate and sexual love were used as manipulations. Results from the studies suggest that exposure to subtle reminders of companionate love lead to a greater likelihood of making healthy eating choices than subtle reminders of sexual love. These choices are likely driven by the activation of distal and proximal temporal construals. Interestingly, subtle reminders of sexual love appear to mimic a choice setting with no manipulation. This research should enlighten marketers who are interested in fostering healthy consumption.


Comparison of Acceptance-based and Standard Cognitive-based Coping Strategies for Craving Sweets in Overweight and Obese Women

Evan Forman et al.
Eating Behaviors, January 2013, Pages 64-68

Existing strategies for coping with food cravings are of unknown efficacy and rely on principles that have been shown to have paradoxical effects. The present study evaluated novel, acceptance-based strategies for coping with craving by randomly assigning 48 overweight women to either an experimental psychological acceptance-oriented intervention or a standard cognitive reappraisal/distraction intervention. Participants were required to carry a box of sweets on their person for 72 hours while abstaining from any consumption of sweets. Results suggested that the acceptance-based coping strategies resulted in lower cravings and reduced consumption, particularly for those who demonstrate greater susceptibility to the presence of food and report a tendency to engage in emotional eating.


Incentivizing Children's Fruit and Vegetable Consumption: Results of a United States Pilot Study of the Food Dudes Program

Heidi Wengreen et al.
Journal of Nutrition Education and Behavior, forthcoming

Objective: Preliminary evaluation in the United States (US) of a school-based fruit and vegetable (F/V) intervention, known as the Food Dudes (FD) program, developed in the United Kingdom.

Methods: Over 16 days (Phase 1), elementary-school children (n = 253) watched short videos featuring heroic peers (the FD) eating F/V and received a reward for eating F/V served at lunchtime. In the 3 months that followed (Phase 2), children received increasingly intermittent rewards for eating F/V. Consumption was measured by photo analysis and assessment of skin carotenoids.

Results: Fruit and vegetable intake increased significantly after Phases 1 and 2 (P < .001 for both). This effect was most discriminable among children who consumed no fruit (n = 100) or no vegetables (n = 119) at pre-intervention baseline. Among these children, F/V intake (combined) increased by 0.49 (0.53) cups per day.

Conclusions and Implications: The FD program can increase F/V intake in US elementary schools.


Copy Number Variations Associated With Obesity-Related Traits in African Americans: A Joint Analysis Between GENOA and HyperGEN

Wei Zhao et al.
Obesity, December 2012, Pages 2431-2437

Obesity is a highly heritable trait and a growing public health problem. African Americans (AAs) are a genetically diverse, yet understudied population with a high prevalence of obesity (BMI >30 kg/m2). Recent studies based upon single-nucleotide polymorphisms (SNPs) have identified genetic markers associated with obesity. However, a large proportion of the heritability of obesity remains unexplained. Copy number variation (CNV) has been cited as a possible source of missing heritability in common diseases such as obesity. We conducted a CNV genome-wide association study of BMI in two African-American cohorts from Genetic Epidemiology Network of Arteriopathy (GENOA) and Hypertension Genetic Epidemiology Network (HyperGEN). We performed independent and identical association analyses in each study, then combined the results in a meta-analysis. We identified three CNVs associated with BMI, obesity, and other obesity-related traits after adjusting for multiple testing. These CNVs overlap the PARK2, GYPA, and SGCZ genes. Our results suggest that CNV may play a role in the etiology of obesity in AAs.


Dietary Salt Intake, Sugar-Sweetened Beverage Consumption, and Obesity Risk

Carley Grimes et al.
Pediatrics, forthcoming

Objective: To determine the association among dietary salt, fluid, and sugar-sweetened beverage (SSB) consumption and weight status in a nationally representative sample of Australian children aged 2 to 16 years.

Methods: Cross-sectional data from the 2007 Australian National Children's Nutrition and Physical Activity Survey. Consumption of dietary salt, fluid, and SSB was determined via two 24-hour dietary recalls. BMI was calculated from recorded height and weight. Regression analysis was used to assess the association between salt, fluid, SSB consumption, and weight status.

Results: Of the 4283 participants, 62% reported consuming SSBs. Older children and those of lower socioeconomic status (SES) were more likely to consume SSBs (both Ps < .001). Dietary salt intake was positively associated with fluid consumption (r = 0.42, P < .001); each additional 1 g/d of salt was associated with a 46 g/d greater intake of fluid, adjusted for age, gender, BMI, and SES (P < .001). In those consuming SSBs (n = 2571), salt intake was positively associated with SSB consumption (r = 0.35, P < .001); each additional 1 g/d of salt was associated with a 17 g/d greater intake of SSB, adjusted for age, gender, SES, and energy (P < .001). Participants who consumed more than 1 serving (≥250 g) of SSB were 26% more likely to be overweight/obese (odds ratio: 1.26, 95% confidence interval: 1.03-1.53).

Conclusions: Dietary salt intake predicted total fluid consumption and SSB consumption within consumers of SSBs. Furthermore, SSB consumption was associated with obesity risk. In addition to the known benefits of lowering blood pressure, salt reduction strategies may be useful in childhood obesity prevention efforts.


Distraction, the desire to eat and food intake. Towards an expanded model of mindless eating

Jane Ogden et al.
Appetite, forthcoming

This study compared the impact of different forms of distraction on eating behaviour with a focus on the mechanisms behind this association and the link between the amount consumed and changes in the desire to eat. Participants (n = 81) were randomly allocated to four conditions: driving, television viewing, social interaction or being alone in which they took part in a taste test. Measures of the desire to eat (i.e. Hunger, fullness, motivation to eat) were assessed before and after the intervention. The results showed that those watching television consumed more than the social or driving conditions. Food intake was associated with a decreased desire to eat for those eating alone, but was unrelated to changes in the desire to eat for those driving. Watching television also created a decrease in the desire to eat commensurate with food intake whereas social eating resulted in the reverse relationship. The results are discussed in terms an expanded model of mindless eating and it is argued that eating more requires not only distraction away from the symptom of hunger but also sufficient cognitive capacity left to attend to the process of eating.


Changes in Eating and Physical Activity Behaviors Across Seven Semesters of College: Living On or Off Campus Matters

Meg Small et al.
Health Education & Behavior, forthcoming

The transition from adolescence to adulthood is an important period for establishing behavioral patterns that affect long-term health and chronic disease risk. Nelson and colleagues speculated that developmental changes and changes in living situation may play an important role in the nutrition and physical activity behaviors of college students. Data from the University Life Study, a longitudinal study of college students that includes web-based surveys administered 14 consecutive days each semester, were used to examine fruit, vegetable, and sugared soda consumption, physical activity, and sedentary activity behaviors across seven semesters. Estimates for each semester were calculated to determine the frequency with which students consumed fruits, vegetables, and sugared soda, engaged in moderate to vigorous physical activity, and engaged in sedentary activities. Four models, estimated with HLM 6.04, were used to predict changes in these behaviors across the seven semesters. Living on or off campus was included to determine if this explained additional variance. Results indicated that few college students consumed fruits and vegetables or exercised at optimal levels during the seven semesters surveyed. Daily fruit and vegetable consumption and daily physical activity declined significantly from the first to the seventh semester. For both of these findings, living off campus exacerbated the problem. Average number of hours of sedentary behaviors declined over time, as did number of days on which at least one sugared soda was consumed. Living location did not explain additional variance in these positive trends. Implications for policy, practice, and future research are discussed.

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