Downsizing
Regulating the Way to Obesity: Unintended Consequences of Limiting Sugary Drink Sizes
Brent Wilson, Stephanie Stolarz-Fantino & Edmund Fantino
PLoS ONE, April 2013
Objectives: We examined whether a sugary drink limit would still be effective if larger-sized drinks were converted into bundles of smaller-sized drinks.
Methods: In a behavioral simulation, participants were offered varying food and drink menus. One menu offered 16 oz, 24 oz, or 32 oz drinks for sale. A second menu offered 16 oz drinks, a bundle of two 12 oz drinks, or a bundle of two 16 oz drinks. A third menu offered only 16 oz drinks for sale. The method involved repeated elicitation of choices, and the instructions did not mention a limit on drink size.
Results: Participants bought significantly more ounces of soda with bundles than with varying-sized drinks. Total business revenue was also higher when bundles rather than only small-sized drinks were sold.
Conclusions: Our research suggests that businesses have a strong incentive to offer bundles of soda when drink size is limited. Restricting larger-sized drinks may have the unintended consequence of increasing soda consumption rather than decreasing it.
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Ecological Contingencies in Women's Calorie Regulation Psychology: A Life History Approach
Sarah Hill et al.
Journal of Experimental Social Psychology, forthcoming
Abstract:
We used insights from life history theory and the critical fat hypothesis to explore how environmental harshness influences women's food and weight regulation psychology. As predicted by our theoretical model, women who grew up in poorer, more unpredictable environments responded to harshness cues in their adult environments by exhibiting a greater desire for food (Studies 1 and 2) and a diminished concern with calorie restriction and weight loss (Study 3). In sharp contrast, women who grew up in more predictable, wealthier environments responded to these cues by exhibiting a diminished desire for food and increased concern with calorie restriction and weight loss. This research provides novel insights into the role that local environmental factors play in women's food and weight regulation psychology.
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Weightism, Racism, Classism, and Sexism: Shared Forms of Harassment in Adolescents
Michaela Bucchianeri et al.
Journal of Adolescent Health, forthcoming
Purpose: To document the prevalence of harassment on the basis of weight, race/ethnicity, and socioeconomic status, as well as sexual harassment, among a diverse population of adolescents. Specifically, this study examined rates of each type of harassment reported across groups within the corresponding sociodemographic category (e.g., racial/ethnic category differences in prevalence of racial harassment), and also explored patterns of "cross-harassment" (i.e., differences in prevalence of each harassment type across all other sociodemographic characteristics).
Methods: We used data from Project Eating and Activity in Teens 2010 for the study. The sample was composed of 2,793 adolescents (53% female; 81% nonwhite). We conducted regression analyses to yield prevalence estimates of each type of harassment in each demographic and body mass index category.
Results: Weight- and race-based harassment (35.3% and 35.2%, respectively) was most prevalent, followed by sexual harassment (25.0%) and socioeconomic status-based harassment (16.1%). Overweight and obese adolescents reported disproportionately higher rates of all forms of harassment than did normal-weight and underweight adolescents. In addition, Asian and mixed-/other race adolescents were more vulnerable to harassment overall compared with those from other racial/ethnic groups.
Conclusions: Harassment experiences are prevalent among adolescent boys and girls. Differential rates of each type of harassment are reported across groups within the corresponding sociodemographic category, but a pattern of cross-harassment also is evident, such that differences in prevalence of each type of harassment emerge across a variety of sociodemographic characteristics. Adolescents from various intersecting sociodemographic and weight-status groups are particularly vulnerable to certain types of harassment.
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Andreana Kenrick, Jenessa Shapiro & Steven Neuberg
Social Psychological and Personality Science, forthcoming
Abstract:
This study examined whether and under what conditions parents might stereotype their own heavyweight children. Parents completed a survey assessing their beliefs about their 9- to 11-year-old children. Parents were also assessed on factors previously demonstrated to moderate people's reactions to heavyweight strangers, including Protestant work ethic (PWE) and personal vulnerability to disease. Consistent with findings on how people view heavyweight strangers, parents who endorsed the PWE or had enhanced disease concerns attributed negative fat stereotypes (e.g., laziness, lacking self-control) to their heavyweight children. Although parental identification did not moderate stereotyping of one's overweight children, those individuals who highly identified with their role as parents spent more time with their heavier-weight children, potentially reflecting a compensatory pattern of behaviors. That even parents negatively stereotype their young heavyweight children reveals the long reach of the anti-fat psychology and suggests that efforts to mitigate the application of fat stereotypes may be particularly difficult.
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Sarah Cohen et al.
PLoS ONE, April 2013
Abstract:
Increased sedentary behavior and lack of physical activity are associated with increased risk for many chronic diseases. Differences in leisure-time physical activity between African American and white adults have been suggested to partially explain racial disparities in chronic disease outcomes, but expanding the definition of physical activity to include household and occupational activities may reduce or even eliminate racial differences in total physical activity. The objective of this study was to describe patterns of active and sedentary behaviors in black and white adults and to examine these behaviors across demographic measures. Sedentary and physically active behaviors were obtained from a validated physical activity questionnaire in 23,021 black men, 9,899 white men, 32,214 black women, and 15,425 white women (age 40-79) at enrollment into the Southern Community Cohort Study. Descriptive statistics for sedentary time; light, moderate, and vigorous household/occupational activity; sports/exercise; total activity; and meeting current physical activity recommendations via sports/exercise were examined for each race-sex group. Adjusted means were calculated using multiple linear regression models across demographic measures. Study participants spent approximately 60% of waking time in sedentary behaviors. Blacks reported more television viewing time than whites (45 minutes for females, 15 minutes for males), but when sitting time was expressed as a proportion of overall awake time, minimal racial differences were found. Patterns of light, moderate, and vigorous household/occupational activity were similar in all race/sex groups. 2008 Physical Activity Guidelines for Americans were followed by 16% of women and 25% of men independent of race. Overall, black and white men and women in this study spent the majority of their daily time in sedentary behaviors and less than one-fourth followed current guidelines for physical activity. These results indicate that public health campaigns should focus on both reducing sedentary behavior and increasing physical activity in all adult US populations.
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Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain
Rachel Markwald et al.
Proceedings of the National Academy of Sciences, 2 April 2013, Pages 5695-5700
Abstract:
Insufficient sleep is associated with obesity, yet little is known about how repeated nights of insufficient sleep influence energy expenditure and balance. We studied 16 adults in a 14- to 15-d-long inpatient study and quantified effects of 5 d of insufficient sleep, equivalent to a work week, on energy expenditure and energy intake compared with adequate sleep. We found that insufficient sleep increased total daily energy expenditure by ∼5%; however, energy intake - especially at night after dinner - was in excess of energy needed to maintain energy balance. Insufficient sleep led to 0.82 ± 0.47 kg (±SD) weight gain despite changes in hunger and satiety hormones ghrelin and leptin, and peptide YY, which signaled excess energy stores. Insufficient sleep delayed circadian melatonin phase and also led to an earlier circadian phase of wake time. Sex differences showed women, not men, maintained weight during adequate sleep, whereas insufficient sleep reduced dietary restraint and led to weight gain in women. Our findings suggest that increased food intake during insufficient sleep is a physiological adaptation to provide energy needed to sustain additional wakefulness; yet when food is easily accessible, intake surpasses that needed. We also found that transitioning from an insufficient to adequate/recovery sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to -0.03 ± 0.50 kg weight loss. These findings provide evidence that sleep plays a key role in energy metabolism. Importantly, they demonstrate physiological and behavioral mechanisms by which insufficient sleep may contribute to overweight and obesity.
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Characteristics of Screen Media Use Associated With Higher BMI in Young Adolescents
David Bickham et al.
Pediatrics, forthcoming
Objectives: This study investigates how characteristics of young adolescents' screen media use are associated with their BMI. By examining relationships between BMI and both time spent using each of 3 screen media and level of attention allocated to use, we sought to contribute to the understanding of mechanisms linking media use and obesity.
Methods: We measured heights and weights of 91 13- to 15-year-olds and calculated their BMIs. Over 1 week, participants completed a weekday and a Saturday 24-hour time-use diary in which they reported the amount of time they spent using TV, computers, and video games. Participants carried handheld computers and responded to 4 to 7 random signals per day by completing onscreen questionnaires reporting activities to which they were paying primary, secondary, and tertiary attention.
Results: Higher proportions of primary attention to TV were positively associated with higher BMI. The difference between 25th and 75th percentiles of attention to TV corresponded to an estimated +2.4 BMI points. Time spent watching television was unrelated to BMI. Neither duration of use nor extent of attention paid to video games or computers was associated with BMI.
Conclusions: These findings support the notion that attention to TV is a key element of the increased obesity risk associated with TV viewing. Mechanisms may include the influence of TV commercials on preferences for energy-dense, nutritionally questionable foods and/or eating while distracted by TV. Interventions that interrupt these processes may be effective in decreasing obesity among screen media users.
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Heather Leidy et al.
American Journal of Clinical Nutrition, April 2013, Pages 677-688
Background: Breakfast skipping is a common dietary habit practiced among adolescents and is strongly associated with obesity.
Objective: The objective was to examine whether a high-protein (HP) compared with a normal-protein (NP) breakfast leads to daily improvements in appetite, satiety, food motivation and reward, and evening snacking in overweight or obese breakfast-skipping girls.
Design: A randomized crossover design was incorporated in which 20 girls [mean ± SEM age: 19 ± 1 y; body mass index (in kg/m2): 28.6 ± 0.7] consumed 350-kcal NP (13 g protein) cereal-based breakfasts, consumed 350-kcal HP egg- and beef-rich (35 g protein) breakfasts, or continued breakfast skipping (BS) for 6 d. On day 7, a 10-h testing day was completed that included appetite and satiety questionnaires, blood sampling, predinner food cue-stimulated functional magnetic resonance imaging brain scans, ad libitum dinner, and evening snacking.
Results: The consumption of breakfast reduced daily hunger compared with BS with no differences between meals. Breakfast increased daily fullness compared with BS, with the HP breakfast eliciting greater increases than did the NP breakfast. HP, but not NP, reduced daily ghrelin and increased daily peptide YY concentrations compared with BS. Both meals reduced predinner amygdala, hippocampal, and midfrontal corticolimbic activation compared with BS. HP led to additional reductions in hippocampal and parahippocampal activation compared with NP. HP, but not NP, reduced evening snacking of high-fat foods compared with BS.
Conclusions: Breakfast led to beneficial alterations in the appetitive, hormonal, and neural signals that control food intake regulation. Only the HP breakfast led to further alterations in these signals and reduced evening snacking compared with BS, although no differences in daily energy intake were observed. These data suggest that the addition of breakfast, particularly one rich in protein, might be a useful strategy to improve satiety, reduce food motivation and reward, and improve diet quality in overweight or obese teenage girls.
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Does Weight Affect Children's Test Scores and Teacher Assessments Differently?
Madeline Zavodny
Economics of Education Review, June 2013, Pages 135-145
Abstract:
The prevalence of childhood overweight and obesity increased dramatically in the United States during the past three decades. This increase has adverse public health implications, but its implication for children's academic outcomes is less clear. This paper uses data from five waves of the Early Childhood Longitudinal Study-Kindergarten to examine how children's weight is related to their scores on standardized tests and to their teachers' assessments of their academic ability. The results indicate that children's weight is more negatively related to teacher assessments of their academic performance than to test scores.
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Sleep Duration and Adolescent Obesity
Jonathan Mitchell et al.
Pediatrics, forthcoming
Objectives: Short sleep has been associated with adolescent obesity. Most studies used a cross-sectional design and modeled BMI categories. We sought to determine if sleep duration was associated with BMI distribution changes from age 14 to 18.
Methods: Adolescents were recruited from suburban high schools in Philadelphia when entering ninth grade (n = 1390) and were followed-up every 6 months through 12th grade. Height and weight were self-reported, and BMIs were calculated (kg/m2). Hours of sleep were self-reported. Quantile regression was used to model the 10th, 25th, 50th, 75th, and 90th BMI percentiles as dependent variables; study wave and sleep were the main predictors.
Results: BMI increased from age 14 to 18, with the largest increase observed at the 90th BMI percentile. Each additional hour of sleep was associated with decreases in BMI at the 10th (-0.04; 95% confidence interval [CI]: -0.11, 0.03), 25th (-0.12; 95% CI: -0.20, -0.04), 50th (-0.15; 95% CI: -0.24, -0.06), 75th (-0.25; 95% CI: -0.38, -0.12), and 90th (-0.27; 95% CI: -0.45, -0.09) BMI percentiles. The strength of the association was stronger at the upper tail of the BMI distribution. Increasing sleep from 7.5 to 10.0 hours per day at age 18 predicted a reduction in the proportion of adolescents >25 kg/m2 by 4%.
Conclusions: More sleep was associated with nonuniform changes in BMI distribution from age 14 to 18. Increasing sleep among adolescents, especially those in the upper half of the BMI distribution, may help prevent overweight and obesity.
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A Randomized Controlled Trial of an Appearance-Based Dietary Intervention
Ross Whitehead, Gözde Ozakinci & David Perrett
Health Psychology, forthcoming
Objective: Inadequate fruit and vegetable consumption precipitates preventable morbidity and mortality. The efficacy of an appearance-based dietary intervention was investigated, which illustrates the beneficial effect that fruit and vegetable consumption has on skin appearance.
Methods: Participants were randomly allocated to three groups receiving information-only or a generic or own-face appearance-based intervention. Diet was recorded at baseline and 10 weekly follow-ups. Participants in the generic and own-face intervention groups witnessed on-screen stimuli and received printed photographic materials to illustrate the beneficial effect of fruit and vegetable consumption on skin color.
Results: Controlling for baseline diet, a significant effect of intervention group was found on self-reported fruit and vegetable intake among 46 completers who were free of medical and personal reasons preventing diet change. The own-face appearance-based intervention group reported a significant, sustained improvement in fruit and vegetable consumption whereas the information-only and generic appearance-based intervention groups reported no significant dietary changes.
Conclusions: Seeing the potential benefits of fruit and vegetable consumption on own skin color may motivate dietary improvement.
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Sit Big to Eat Big: The Interaction of Body Posture and Body Concern on Restrained Eating
Jill Allen, Sarah Gervais & Jessi Smith
Psychology of Women Quarterly, forthcoming
Abstract:
Body image concern has long been linked with unhealthy restrained eating patterns among women, yet scant research has examined factors to disrupt this process. At the same time, feminine stereotypes prescribe that women should be small, restrict their movements, speak softly, and limit their food intake (e.g., through dieting). Here, we examined whether women's postural constriction or expansion moderated the relation between body shape concern and restrained eating, predicting that expansive postures would interrupt this robust relation. As a secondary aim, we investigated whether women spontaneously adopted constrictive postures and to what extent postures contributed to restrained eating under baseline conditions. Specifically, women's postural position (constricted, expanded, or baseline posture) was manipulated and restrained eating was measured. Results showed that at high levels of body shape concern, women sitting in expansive postures restrained their eating less compared to women in constrictive postures. Further, spontaneously expansive (vs. spontaneously constrictive) postures were associated with less restrained eating among women. Thus, postural expansion attenuated the link between body shape concern and restrained eating whereas postural constriction exacerbated the link. Implications for gender performativity and possible interventions for restrained eating are discussed.
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Plate Size and Children's Appetite: Effects of Larger Dishware on Self-Served Portions and Intake
Katherine DiSantis et al.
Pediatrics, forthcoming
Objectives: Dishware size is thought to influence eating behaviors, but effects on children's self-served portion sizes and intakes have not been studied. We aimed to evaluate whether larger dishware increased children's self-served portion sizes and intake during meals.
Methods: A within-subjects experimental design was used to test the effects of dishware size (ie, plates and bowls) on children's self-served portion sizes and intakes in a naturalistic setting. Subjects were predominantly African American elementary school-aged children (n = 42) observed on repeated occasions during school lunch. Children served themselves an entree and side dishes using either child- or adult-size dishware, which represented a 100% increase in the surface area of plates and volume of bowls across conditions. Condition order was randomly assigned and counterbalanced across 2 first-grade classrooms. Entrées of amorphous and unit form were evaluated on separate days. Fruit and vegetable side dishes were evaluated at each meal. Fixed portions of milk and bread were provided at each meal.
Results: Children served more energy (mean = 90.1 kcal, SE = 29.4 kcal) when using adult-size dishware. Adult-size dishware promoted energy intake indirectly, where every additional calorie served resulted in a 0.43-kcal increase in total energy intakes at lunch (t = 7.72, P = .001).
Conclusions: Children served themselves more with larger plates and bowls and consumed nearly 50% of the calories that they served. This provides new evidence that children's self-served portion sizes are influenced by size-related facets of their eating environments, which, in turn, may influence children's energy intake.
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Health on Impulse: When Low Self-Control Promotes Healthy Food Choices
Stefanie Salmon et al.
Health Psychology, forthcoming
Objective: Food choices are often made mindlessly, when individuals are not able or willing to exert self-control. Under low self-control, individuals have difficulties to resist palatable but unhealthy food products. In contrast to previous research aiming to foster healthy choices by promoting high self-control, this study exploits situations of low self-control, by strategically using the tendency under these conditions to rely on heuristics (simple decision rules) as quick guides to action. More specifically, the authors associated healthy food products with the social proof heuristic (i.e., normative cues that convey majority endorsement for those products).
Method: One hundred seventy-seven students (119 men), with an average age of 20.47 years (SD = 2.25) participated in the experiment. This study used a 2 (low vs. high self-control) × 2 (social proof vs. no heuristic) × 2 (trade-off vs. control choice) design, with the latter as within-subjects factor. The dependent variable was the number of healthy food choices in a food-choice task.
Results: In line with previous studies, people made fewer healthy food choices under low self-control. However, this negative effect of low self-control on food choice was reversed when the healthy option was associated with the social proof heuristic. In that case, people made more healthy choices under conditions of low self-control.
Conclusion: Low self-control may be even more beneficial for healthy food choices than high self-control in the presence of a heuristic. Exploiting situations of low self-control is a new and promising method to promote health on impulse.
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M.S. Tryon, Rashel DeCant & K.D. Laugero
Physiology & Behavior, forthcoming
Abstract:
Stress has been tied to changes in eating behavior and food choice. Previous studies in rodents have shown that chronic stress increases palatable food intake which, in turn, increases mesenteric fat and inhibits acute stress-induced hypothalamic-pituitary-adrenal (HPA) axis activity. The effect of chronic stress on eating behavior in humans is less understood, but it may be linked to HPA responsivity. The purpose of this study was to investigate the influence of chronic social stress and acute stress reactivity on food choice and food intake. Forty-one women (BMI = 25.9 ± 5.1 kg/m2, age range = 41 to 52 years) were subjected to the Trier Social Stress Task or a control task (nature movie) to examine HPA responses to an acute laboratory stressor and then invited to eat from a buffet containing low- and high- calorie "comfort" snacks. Women were also categorized as high chronic stress or low chronic stress based on Wheaton Social Stress Index scores. Women reporting higher chronic stress and exhibiting low cortisol reactivity to the acute stress task consumed significantly more calories from chocolate cake on both stress and control visits. Chronic stress in the low cortisol reactor group was also positively related to total fat mass, regional fat percentage, and stress-induced negative mood. Further, women reporting high chronic stress consumed significantly less vegetables, but only in those aged 45 years and older. Chronic stress in women within the higher age category was positively related to total calories consumed at the buffet, stress-induced negative mood and food craving. Our results suggest an increased risk for stress eating in persons with a specific chronic stress signature and imply that a habit of comfort food may link chronic social stress and acute stress-induced cortisol hyporesponsiveness.
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Weight perceptions, weight control and income: An analysis using British Data
David Johnston & Grace Lordan
Economics & Human Biology, forthcoming
Abstract:
The aim of this paper is to better understand one of the mechanisms underlying the income-obesity relationship so that effective policy interventions can be developed. Our approach involves analysing data on approximately 9,000 overweight British adults from between 1997 and 2002. We estimate the effect of income on the probability that an overweight individual correctly recognises their overweight status and the effect of income on the probability that an overweight individual attempts to lose weight. The results suggest that high income individuals are more likely to recognise their unhealthy weight status, and conditional on this correct weight perception, more likely to attempt weight loss. For example, it is estimated that overweight high income males are 15 percentage-points more likely to recognize their overweight status than overweight low income males, and overweight high income males are 10 percentage-points more likely to be trying to lose weight. An implication of these results is that more public education on what constitutes overweight and the dangers associated with being overweight is needed, especially in low income neighbourhoods.
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Body mass index and neurocognitive functioning across the adult lifespan
Kelly Stanek et al.
Neuropsychology, March 2013, Pages 141-151
Objective: Cognitive dysfunction and structural brain abnormalities have been observed in obese versus lean individuals, but with variability across age and weight groups. The current study was designed to clarify the cognitive profile of obesity by examining performance across multiple cognitive domains in adults with wide-ranging age and weight status.
Method: Participants (N = 732; 61% women; ages 18-88; BMI range 19-75) underwent assessment of cognitive functioning and relevant medical/demographic covariates. Neuropsychological tests were grouped by cognitive domain (via confirmatory factor analysis), and standardized scores were averaged into composite variables.
Results: Hierarchical linear regression analyses revealed main effects for BMI on motor (ΔR2 = .02, β = -.15) and attention/processing speed (ΔR2 = .01, β = -.07), whereas a significant interaction between BMI and age was observed (ΔR2 = .01, β = -.08) for predicting executive functioning (p < .05). BMI was not independently associated with memory or language functioning and no interaction effects were observed for these variables. Although BMI was not independently related to executive dysfunction, a significant age × BMI interaction suggests that obesity-related executive deficits may increase with age.
Conclusions: Overall, these findings may support an independent association between obesity and a frontal-subcortical pathology, though prospective studies are needed to further clarify this possibility.
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Perceived and actual social discrimination: The case of overweight and social inclusion
Freda-Marie Hartung & Britta Renner
Frontiers in Psychology, April 2013
Abstract:
The present study examined the correspondence between perceived and actual social discrimination of overweight people. In total, 77 first-year students provided self-ratings about their height, weight, and perceived social inclusion. To capture actual social inclusion, each participant nominated those fellow students (a) she/he likes and dislikes and (b) about whom she/he is likely to hear social news. Students with lower Body Mass Index (BMI) felt socially included, irrespective of their actual social inclusion. In contrast, students with higher BMI felt socially included depending on the degree of their actual social inclusion. Specifically, their felt social inclusion accurately reflected whether they were actually liked/disliked, but only when they were part of social news. When not part of social news, they also showed insensitivity to their actual social inclusion status. Thus, students with a lower BMI tended to be insensitive, while students with a higher BMI showed a differential sensitivity to actual social discrimination.
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Ming Wen & Thomas Maloney
Economics & Human Biology, forthcoming
Abstract:
We build on recent work examining the BMI patterns of immigrants in the US by distinguishing between legal and undocumented immigrants. We find that undocumented women have relative odds of obesity that are about 10 percentage points higher than for legal immigrant women, and their relative odds of being overweight are about 40 percentage points higher. We also find that the odds of obesity and overweight status vary less across neighborhoods for undocumented women than for legal immigrant women. These patterns are not found among immigrant men: undocumented men have lower rates of obesity (by about 6 percentage points in terms of relative odds) and overweight (by about 12 percentage points) than do legal immigrant men, and there is little variation in the impact of neighborhood context across groups of men. We interpret these findings in terms of processes of acculturation among immigrant men and women.
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John Cawley, Rosemary Avery & Matthew Eisenberg
NBER Working Paper, March 2013
Abstract:
This paper is the first to estimate the impact of exposure to deceptive advertising on consumption of the advertised product and its substitutes. We study the market for over-the-counter (OTC) weight-loss products, a market in which deceptive advertising is rampant and products are generally ineffective with potentially serious side effects. We control for the targeting of ads using indicator variables for each unique magazine read and television show watched. Our estimates indicate that exposure to deceptive advertising is associated with a lower probability that women, and a higher probability that men, consume OTC weight loss products. We find evidence of spillovers; exposure to deceptive print ads is associated with a higher probability of dieting and exercising for both men and women. We also find evidence that better-educated individuals are more sophisticated consumers of advertising and use it to make more health-promoting decisions.
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A.M. Adachi-Mejia et al.
Public Health, forthcoming
Objectives: The 2010 Dietary Guidelines for Americans include reducing consumption of sugar-sweetened beverages. Among the many possible routes of access for youth, school vending machines provide ready availability of sugar-sweetened beverages. The purpose of this study was to determine variation in high school student access to sugar-sweetened beverages through vending machines by geographic location - urban, town or rural - and to offer an approach for analysing school vending machine content.
Study design: Cross-sectional observational study.
Methods: Between October 2007 and May 2008, trained coders recorded beverage vending machine content and machine-front advertising in 113 machines across 26 schools in New Hampshire and Vermont, USA.
Results: Compared with town schools, urban schools were significantly less likely to offer sugar-sweetened beverages (P = 0.002). Rural schools also offered more sugar-sweetened beverages than urban schools, but this difference was not significant. Advertisements for sugar-sweetened beverages were highly prevalent in town schools.
Conclusions: High school students have ready access to sugar-sweetened beverages through their school vending machines. Town schools offer the highest risk of exposure; school vending machines located in towns offer up to twice as much access to sugar-sweetened beverages in both content and advertising compared with urban locations. Variation by geographic region suggests that healthier environments are possible and some schools can lead as inspirational role models.
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Two Functional Serotonin Polymorphisms Moderate the Effect of Food Reinforcement on BMI
Katelyn Carr et al.
Behavioral Neuroscience, forthcoming
Abstract:
Food reinforcement, or the motivation to eat, has been associated with increased energy intake, greater body weight, and prospective weight gain. Much of the previous research on the reinforcing value of food has focused on the role of dopamine, but it may be worthwhile to examine genetic polymorphisms in the serotonin and opioid systems as these neurotransmitters have been shown to be related to reinforcement processes and to influence energy intake. We examined the relationship among 44 candidate genetic polymorphisms in the dopamine, serotonin, and opioid systems, as well as food reinforcement and body mass index (BMI) in a sample of 245 individuals. Polymorphisms in the monoamine oxidase A (MAOA-LPR) and serotonin receptor 2A genes (rs6314) moderated the effect of food reinforcement on BMI, accounting for an additional 5-10% variance and revealed a potential role of the single nucleotide polymorphism, rs6314, in the serotonin 2A receptor as a differential susceptibility factor for obesity. Differential susceptibility describes a factor that can confer either risk or protection depending on a second variable, such that rs6314 is predictive of both high and low BMI based on the level of food reinforcement, while the diathesis stress or dual-gain model only influences one end of the outcome measure. The interaction with MAOA-LPR better fits the diathesis stress model, with the 3.5R/4R allele conferring protection for individuals low in food reinforcement. These results provide new insight into genes theoretically involved in obesity, and support the hypothesis that genetics moderate the association between food reinforcement and BMI.
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Keith Babbs et al.
Physiology & Behavior, forthcoming
Abstract:
Previous investigations consistently report a negative association between body mass index (BMI) and response in the caudate nucleus during the consumption of palatable and energy dense food. Since this response has also been linked to weight gain, we sought to replicate this finding and determine if the reduced response is associated with measures of impulsivity or food reward. Two studies were conducted in which fMRI was used to measure brain response to milkshake and a tasteless control solution. In Study 1 (n = 25) we also assessed self-reported impulsivity, willingness to work for food, and subjective experiences of the pleasantness of milkshake taste and aroma. Replicating prior work, we report a negative association between BMI and brain response to milkshake vs. tasteless in the caudate nucleus. The opposite pattern was observed in the ventral putamen, with greater response observed in the 13 overweight compared to the 12 healthy weight subjects. Regression of brain response against impulsivity and food reward measures revealed one significant association: in the overweight but not healthy weight group self-reported impulsivity was negatively associated with caudate response to milkshake. In Study 2 (n = 14), in addition to assessing brain response to milkshake and tasteless solutions subjects completed a go/no-go task outside the scanner. As predicted, we identified an inverse relationship between caudate response to milkshake vs. tasteless and failure to inhibit responses on the no-go trials. We conclude that the inverse correlation between BMI and caudate response to milkshake is associated with impulsivity but not food reward. These findings suggest that response to milkshake in the dorsal striatum may be related to weight gain by promoting impulsive eating behavior.
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Wei He et al.
PLoS ONE, March 2013
Introduction: Chinese are reported to have a higher percent body fat (¿) and a higher percent trunk fat (%TF) than whites for a given body mass index (BMI). However, the associations of these ethnic differences in body composition with metabolic risks remain unknown.
Methods and Procedures: A total of 1 029 Chinese from Hangzhou, China, and 207 whites from New York, NY, USA, were recruited in the present study. Body composition was measured using dual-energy X-ray absorptiometry (DXA). Analysis of covariance was used to assess the ethnic differences in fat, fat distribution, and metabolic risk factors.
Results: After adjusting for BMI, age, and height, Chinese men had an average of 3.9% more ¿ and 12.1% more %TF than white men; Chinese women had an average of 2.3% more ¿ and 11.8% more %TF than white women. Compared with whites, higher metabolic risks were detected in Chinese for a given BMI after adjusting for age and height. Further adjustment for ¿ did not change these ethnic disparities. However, after adjusting for %TF, the ethnic differences decreased and become insignificant in triglyceride, high-density lipoprotein cholesterol, and blood pressure (except for systolic blood pressure in men). For fasting plasma glucose, the ethnic differences persisted after adjustment for ¿, but decreased significantly from 0.910 to 0.686 mmol/L among men, and from 0.629 to 0.355 mmol/L among women, when the analyses were further controlled for %TF.
Discussion: Chinese have both higher ¿ and %TF than white people for a given BMI. However, only %TF could in part account for the higher metabolic risk observed in Chinese men and women.
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Timing of Solid Food Introduction and Obesity: Hong Kong's "Children of 1997" Birth Cohort
Shi Lin Lin et al.
Pediatrics, forthcoming
Background: Some observational studies in Western settings show that early introduction of solid food is associated with subsequent obesity. However, introduction of solid food and obesity share social patterning. We examined the association of the timing of the introduction of solid food with BMI and overweight (including obesity) into adolescence in a developed non-Western setting, in which childhood obesity is less clearly socially patterned.
Methods: We used generalized estimating equation models to estimate the adjusted associations of the timing of the introduction of solid food (<3, 3-4, 5-6, 7-8, and >8 months) with BMI z score and overweight (including obesity) at different growth phases (infancy, childhood, and puberty) in 7809 children (88% follow-up) from a Chinese birth cohort, "Children of 1997." We assessed if the associations varied with gender or breastfeeding. We used multiple imputation for missing exposure and confounders.
Results: The introduction of solid food at <3 months of age was associated with lower family socioeconomic position (SEP) but was not clearly associated with BMI or overweight (including obesity) in infancy [mean difference in BMI z score: 0.01; 95% confidence interval (CI): -0.14 to 0.17], childhood (0.14; 95% CI: -0.11 to 0.40), or at puberty (0.22; 95% CI: -0.07 to 0.52), adjusted for SEP and infant and maternal characteristics.
Conclusions: In a non-Western developed setting, there was no clear association of the early introduction of solid food with childhood obesity. Together with the inconsistent evidence from studies in Western settings, this finding suggests that any observed associations might simply be residual confounding by SEP.
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Richard Martin et al.
Journal of the American Medical Association, 13 March 2013, Pages 1005-1013
Importance: Evidence that longer-term and exclusive breastfeeding reduces child obesity risk is based on observational studies that are prone to confounding.
Objective: To investigate effects of an intervention to promote increased duration and exclusivity of breastfeeding on child adiposity and circulating insulin-like growth factor (IGF)-I, which regulates growth.
Design, Setting, and Participants: Cluster-randomized controlled trial in 31 Belarusian maternity hospitals and their affiliated clinics, randomized into 1 of 2 groups: breastfeeding promotion intervention (n = 16) or usual practices (n = 15). Participants were 17 046 breastfeeding mother-infant pairs enrolled in 1996 and 1997, of whom 13 879 (81.4%) were followed up between January 2008 and December 2010 at a median age of 11.5 years.
Intervention: Breastfeeding promotion intervention modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative (World Health Organization/United Nations Children's Fund).
Main Outcome Measures: Body mass index (BMI), fat and fat-free mass indices (FMI and FFMI), percent body fat, waist circumference, triceps and subscapular skinfold thicknesses, overweight and obesity, and whole-blood IGF-I. Primary analysis was based on modified intention-to-treat (without imputation), accounting for clustering within hospitals and clinics.
Results: The experimental intervention substantially increased breastfeeding duration and exclusivity when compared with the control (43% vs 6% exclusively breastfed at 3 months and 7.9% vs 0.6% at 6 months). Cluster-adjusted mean differences in outcomes at 11.5 years of age between experimental vs control groups were: 0.19 (95% CI, -0.09 to 0.46) for BMI; 0.12 (-0.03 to 0.28) for FMI; 0.04 (-0.11 to 0.18) for FFMI; 0.47% (-0.11% to 1.05%) for percent body fat; 0.30 cm (-1.41 to 2.01) for waist circumference; -0.07 mm (-1.71 to 1.57) for triceps and -0.02 mm (-0.79 to 0.75) for subscapular skinfold thicknesses; and -0.02 standard deviations (-0.12 to 0.08) for IGF-I. The cluster-adjusted odds ratio for overweight/obesity (BMI ≥85th vs <85th percentile) was 1.18 (95% CI, 1.01 to 1.39) and for obesity (BMI ≥95th vs <85th percentile) was 1.17 (95% CI, 0.97 to 1.41).
Conclusions and Relevance: Among healthy term infants in Belarus, an intervention that succeeded in improving the duration and exclusivity of breastfeeding did not prevent overweight or obesity, nor did it affect IGF-I levels at age 11.5 years. Breastfeeding has many advantages but population strategies to increase the duration and exclusivity of breastfeeding are unlikely to curb the obesity epidemic.
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Jessica McNeil et al.
Physiology & Behavior, 15 March 2013, Pages 84-89
Abstract:
Increases in energy, lipid and carbohydrate intakes during the luteal phase have been previously observed. However, it is not known whether this is due to phase-dependent variations in the reward value of certain foods. Moreover, increases in olfactory sensitivity have been proposed and may be involved in these changes in food reward. Therefore, we examined olfactory performance and the reward value of foods varying in fat content and taste. Seventeen women (Body mass index: 22.3 ± 1.6 kg/m2; Body fat-DXA: 28.5 ± 6.8%) were recruited to participate in 3 identical sessions, performed during distinct phases of the menstrual cycle - early follicular/menstruation, late follicular/ovulation and mid-luteal - verified by plasma sex-steroid hormones and oral temperature. Food preference, implicit wanting, and explicit wanting and liking for visual food cues, varying in fat content and taste, were measured with a validated experimental platform involving a forced choice computer task. Odour threshold, odour discrimination, odour identification and total odour scores were measured using odourized pens. Ad libitum energy and macronutrient intakes was measured with a validated food menu. Results showed greater total odour scores (p < 0.05), explicit wanting for high fat foods (p < 0.05) and lipid intake (p < 0.05) during the mid-luteal phase. Inter-correlations between these variables were non-significant. These findings support previous observations of increased lipid intake during the luteal phase and provide evidence for phase-dependent variation in overall olfactory performance and explicit wanting for high fat foods.
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Perceived Environmental Church Support and Physical Activity Among Black Church Members
Meghan Baruth et al.
Health Education & Behavior, forthcoming
Background: Churches are an appealing setting for implementing health-related behavior change programs. Purpose. The objective of the study was to examine the relationship between perceived environmental church support for physical activity (PA) and PA behaviors.
Method: Black church members from South Carolina (n = 309) wore an Actigraph accelerometer prior to the initiation of an intervention. Relationships between moderate to vigorous PA (MVPA; counts ≥1,952), light PA (LPA; counts 100-1951), sedentary behavior (counts <100), and perceived environmental church support for PA (total, spoken informational, written informational, instrumental) were examined. Support × Gender interactions examined whether relationships differed by gender.
Results: The mean age was 54.0 ± 12.3 years and mean body mass index was 32.9 ± 7.2 kg/m2. On average, participants engaged in 14.4 ± 13.7 minutes/day of MVPA, 289.8 ± 82.4 minutes/day of LPA, and were sedentary 548.9 ± 102.2 minutes/day. Total, spoken informational, and written informational church support were significantly related to higher levels of LPA and lower levels of sedentary behavior in men but not women. The relationship between written informational support and MVPA approached significance for men but not women. Instrumental church support was not associated with PA behaviors.
Conclusion: The church environment may have an important influence on Black church members' PA behavior, particularly men's, and thus should be targeted in interventions.
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R. Mathur et al.
Journal of Clinical Endocrinology & Metabolism, April 2013, Pages E698-E702
Context: Colonization of the gastrointestinal tract with methanogenic archaea (methanogens) significantly affects host metabolism and weight gain in animal models, and breath methane is associated with a greater body mass index (BMI) among obese human subjects.
Objective: The objective of the study was to characterize the relationship between methane and hydrogen on breath test (as a surrogate for colonization with the hydrogen requiring methanogen, Methanobrevibacter smithii), body weight, and percent body fat in a general population cohort.
Design and Subjects: This was a prospective study (n = 792) of consecutive subjects presenting for breath testing.
Setting: The study was conducted at a tertiary care center.
Outcome Measurements: BMI and percent body fat were measured.
Results: Subjects were classified into 4 groups based on breath testing: normal (N) (methane <3 ppm and hydrogen <20 ppm at or before 90 minutes); hydrogen positive only (H+) [methane <3 ppm and hydrogen ≥20 ppm); methane positive only (M+) (methane ≥3 ppm and hydrogen <20 ppm), or methane and hydrogen positive (M+/H+) (methane ≥3 ppm and hydrogen ≥20 ppm]. There were significant differences in age but not in gender across the groups. After controlling for age as a confounding variable, M+/H+ subjects had significantly higher BMI than other groups (N: 24.1 ± 5.2 kg/m2; H+: 24.2 ± 4.5 kg/m2; M+: 24.0 ± 3.75 kg/m2; M+/H+: 26.5 ± 7.1 kg/m2, P < .02) and also had significantly higher percent body fat (N: 28.3 ± 10.0%; H+: 27.5 ± 9.0%; M+: 28.0 ± 8.9%; M+/H+; 34.1 ± 10.9%, P < .001).
Conclusions: The presence of both methane and hydrogen on breath testing is associated with increased BMI and percent body fat in humans. We hypothesize that this is due to colonization with the hydrogen-requiring M smithii, which affects nutrient availability for the host and may contribute to weight gain.