Pre-existing Condition
Eating for Pleasure or Profit: The Effect of Incentives on Children's Enjoyment of Vegetables
Lucy Cooke et al.
Psychological Science, forthcoming
Abstract:
Parents commonly use rewards to encourage children to eat healthfully, but this practice remains controversial because rewards are suspected of undermining children's intrinsic motivation. A cluster-randomized trial examined children's acceptance of a disliked vegetable over 12 daily taste exposures. These exposures were paired with a tangible reward, a social reward, or no reward, and the findings were compared with the results from a no-treatment control condition. Liking and intake of the vegetable were assessed in a free-choice consumption task at preintervention, postintervention, 1 month after intervention, and 3 months after intervention. Liking increased more in the three intervention conditions than in the control condition, and there were no significant differences between the intervention conditions. These effects were maintained at follow-up. Children in both reward conditions increased consumption, and these effects were maintained for 3 months; however, the effects of exposure with no reward became nonsignificant by 3 months. These results indicate that external rewards do not necessarily produce negative effects and may be useful in promoting healthful eating.
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How Does the Business Cycle Affect Eating Habits?
Dhaval Dave & Inas Rashad Kelly
NBER Working Paper, December 2010
Abstract:
As economic expansions raise employment and wages, associated shifts in income and time constraints would be expected to also impact individuals' health. This study utilizes information from the Behavioral Risk Factor Surveillance System (1990-2007) to explore the relationship between the risk of unemployment and the consumption of various healthy and unhealthy foods. Estimates, based on fixed effects methodologies, indicate that a higher risk of unemployment is associated with reduced consumption of fruits and vegetables and increased consumption of "unhealthy" foods such as snacks and fast food. In addition to estimation of the average population effect, heterogeneous responses are also identified through detailed sample stratifications and by isolating the effect for those predicted to be at highest risk of unemployment based on their socio-economic characteristics. Among individuals predicted to be at highest risk of being unemployed, a one percentage point increase in the resident state's unemployment rate is associated with a 2-8% reduction in the consumption of fruits and vegetables. The impact is somewhat higher among married individuals and older adults. Supplementary analyses also explore specific mediating pathways, and point to reduced family income and adverse mental health as significant channels underlying the procyclical nature of healthy food consumption.
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Are Restaurants Really Supersizing America?
Michael Anderson & David Matsa
American Economic Journal: Applied Economics, January 2011, Pages 152-188
Abstract:
While many researchers and policymakers infer from correlations between eating out and body weight that restaurants are a leading cause of obesity, a basic identification problem challenges these conclusions. We exploit the placement of Interstate Highways in rural areas to obtain exogenous variation in the effective price of restaurants and examine the impact on body mass. We find no causal link between restaurant consumption and obesity. Analysis of food-intake micro-data suggests that consumers offset calories from restaurant meals by eating less at other times. We conclude that regulation targeting restaurants is unlikely to reduce obesity but could decrease consumer welfare.
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Peer Effects and the Freshman 15: Evidence from a Natural Experiment
Olga Yakusheva, Kandice Kapinos & Marianne Weiss
Economics & Human Biology, forthcoming
Abstract:
This study investigates the importance of peer effects in explaining weight gain among freshman college students. We exploit a natural experiment that takes place on most college campuses in the US - randomized roommate assignments. While previous studies suggest that having an obese spouse, friend, or sibling increases one's likelihood of becoming obese, these social interactions are clearly non-random. We collect data from female students living on campus at a private Midwestern university at the beginning and end of their first year of college. Our findings suggest that the amount of weight gained during the freshman year is strongly and negatively correlated to the roommate's initial weight. Further, our analysis of behaviors suggests that female students adopt some of their roommates' weight-loss behaviors which cause them to gain less weight than they otherwise would have. In particular, we find evidence that this effect may be through influences in eating, exercise, and use of weight loss supplements.
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Western diet consumption and cognitive impairment: Links to hippocampal dysfunction and obesity
Scott Kanoski & Terry Davidson
Physiology & Behavior, forthcoming
Abstract:
Intake of saturated fats and simple carbohydrates, two of the primary components of a modern Western diet, is linked with the development of obesity and Alzheimer's Disease. The present paper summarizes research showing that Western diet intake is associated with cognitive impairment, with a specific emphasis on learning and memory functions that are dependent on the integrity of the hippocampus. The paper then considers evidence that saturated fat and simple carbohydrate intake is correlated with neurobiological changes in the hippocampus that may be related to the ability of these dietary components to impair cognitive function. Finally, a model is described proposing that Western diet consumption contributes to the development of excessive food intake and obesity, in part, by interfering with a type of hippocampal-dependent memory inhibition that is critical in the ability of animals to refrain from responding to environmental cues associated with food, and ultimately from consuming energy intake in excess of that driven solely by caloric need.
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Terry Davidson, Ashley Martin, Kiely Clark & Susan Swithers
Quarterly Journal of Experimental Psychology, forthcoming
Abstract:
Recent results from both human epidemiological and experimental studies with animals suggest that intake of non-caloric sweeteners may promote, rather than protect against, weight gain and other disturbances of energy regulation. However, without a viable mechanism to explain how consumption of non-caloric sweeteners can increase energy intake and body weight, the persuasiveness of such results has been limited. Using a rat model, the present research showed that intake of non-caloric sweeteners reduces the effectiveness of learned associations between sweet tastes and postingestive caloric outcomes (Experiment 1) and that interfering with this association may impair the ability of rats to regulate their intake of sweet, but not nonsweet, high-fat and high-calorie food (Experiment 2). The results support the hypothesis that consuming noncaloric sweeteners may promote excessive intake and body weight gain by weakening a predictive relationship between sweet taste and the caloric consequences of eating.
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Alexander Chernev
Journal of Consumer Psychology, forthcoming
Abstract:
Despite the vast public policy efforts to promote the consumption of healthy foods and the public's growing concern with weight management, the proportion of overweight individuals continues to increase. An important factor contributing to this obesity trend is the misguided belief about the relationship between a meal's healthiness and its impact on weight gain, whereby people erroneously believe that eating healthy foods in addition to unhealthy ones can decrease a meal's calorie count. This research documents this misperception, showing that it is stronger among individuals most concerned with managing their weight - a striking result given that these individuals are more motivated to monitor their calorie intake. This finding has important public policy implications, suggesting that in addition to encouraging the adoption of a healthier lifestyle among overweight individuals, promoting the consumption of healthy foods might end up facilitating calorie overconsumption, leading to weight gain rather than weight loss.
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Abay Asfaw
Health Economics, February 2011, Pages 184-195
Abstract:
Overweight/obesity, caused by the ‘nutrition transition', is identified as one of the leading risk factors for non-communicable mortality. The nutrition transition in developing countries is associated with a major shift from the consumption of staple crops and whole grains to highly and partially processed foods. This study examines the contribution of processed foods consumption to the prevalence of overweight/obesity in Guatemala using generalized methods of moments (GMM) regression. The results show that all other things remaining constant, a 10% point increase in the share of partially processed foods from the total household food expenditure increases the BMI of family members (aged 10 years and above) by 3.95%. The impact of highly processed foods is much stronger. A 10% point increase in the share of highly processed food items increases the BMI of individuals by 4.25%, ceteris paribus. The results are robust when body weight is measured by overweight/obesity indicators. These findings suggest that increasing shares of partially and highly processed foods from the total consumption expenditure could be one of the major risk factors for the high prevalence of overweight/obesity in the country.
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Assessment of Community Food Resources: A Latino Neighborhood Study in Upstate New York
Maria Lopez-Class & Akiko Hosler
Journal of Poverty, October 2010, Pages 369-381
Abstract:
This study aims to assess availability, affordability, and accessibility of food items in a low-income Latino neighborhood within a small city using an on-site food store survey. Store locations were identified by on-site Global Positioning System. Results showed the Latino neighborhood had limited availability and above-average cost of high-fiber bread. Fresh vegetables were more expensive compared to the non-Latino neighborhood, and more stores in the Latino neighborhood participated in Supplemental Nutrition Assistance Food Program. The lack of supermarkets, fewer stores with disability access, and the lack of public transportation left Latino residents without a vehicle or with physical disabilities with few food shopping options.
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The Effects of Hurricane Katrina on Food Access Disparities in New Orleans
Donald Rose et al.
American Journal of Public Health, forthcoming
Abstract:
Disparities in neighborhood food access are well documented, but little research exists on how shocks influence such disparities. We examined neighborhood food access in New Orleans at 3 time points: before Hurricane Katrina (2004-2005), in 2007, and in 2009. We combined existing directories with on-the-ground verification and geographic information system mapping to assess supermarket counts in the entire city. Existing disparities for African American neighborhoods worsened after the storm. Although improvements have been made, by 2009 disparities were no better than prestorm levels.
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Alternative Thinking about Starting Points of Obesity: Development of Child Taste Preferences
Bettina Cornwell & Anna McAlister
Appetite, forthcoming
Abstract:
Food marketers are at the epicenter of criticism for the unfolding obesity epidemic as societies consider banning advertising to children and taxing "junk" foods. While marketing's role in obesity is not well understood, there is clear evidence that children are regularly targeted with calorie-dense, nutrient-poor food. Much of the past research seeks to understand how marketing influences brand preference and child requests. The authors argue that understanding palate development offers new insights for discussion. Two studies consider whether a sugar/fat/salt (SFS) palate is linked to children's knowledge of food brands, experience with products, and advertising. In study 1, the authors develop a survey measure of taste preferences and find that a child's SFS palate (as reported by parents) relates significantly to children's self-reported food choices. Study 2 examines how knowledge of certain branded food and drinks is related to palate. Findings show that children with detailed mental representations of fast-food and soda brands - developed via advertising and experience - have higher scores on the SFS palate scale.
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Sofie Lemmens et al.
Physiology & Behavior, forthcoming
Abstract:
Stress may induce eating in the absence of hunger, possibly involving changes in food reward, i.e. ‘liking' and ‘wanting'. The objective of this study was to assess the effects of acute psychological stress on food reward, and on energy intake, in visceral overweight (VO) vs. normal weight (NW) subjects. Subjects (27 NW, age = 26 ± 9 yrs, BMI = 22 ± 2 kg/m2; 15 VO, age = 36 ± 12 yrs, BMI = 28 ± 1 kg/m2) came to the university twice, fasted, for either a rest or stress condition (randomized cross-over design). Per test-session ‘liking' and ‘wanting' for 72 items divided in six categories (bread, filling, drinks, dessert, snacks, and stationery (control)) were measured twice, each time followed by a wanted meal. Appetite profile (visual analogue scales, VAS), heart rate, mood state and level of anxiety (POMS/STAI questionnaires) were measured. High hunger and low satiety (64 ± 19, 22 ± 20 mmVAS) confirmed the fasted state. Elevated heart rate, anger and confusion scores (p ≤ 0.03) confirmed the stress vs. rest condition. Consumption of the first meal decreased hunger, increased satiety, and decreased ranking of ‘liking' of bread vs. increased ranking of ‘liking' of the control (p < 0.001). ‘Wanting' for dessert and snacks, energy intake, carbohydrate and fat intake for the second meal stress vs. rest relatively increased in VO vs. decreased in NW (p < 0.02). During stress vs. rest VO showed a 6 ± 9% increase in percentage of daily energy requirements consumed over the two meals (p = 0.01). To conclude, visceral overweight subjects showed stress-induced food intake in the absence of hunger, resulting in an increased energy intake.
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Marie Hennecke & Alexandra Freund
Psychology and Aging, December 2010, Pages 876-885
Abstract:
In the present study, we investigated whether self-regulation improves across adulthood, especially regarding the mastery of setbacks and failure in an important health-related behavior, namely, staying on a low-calorie diet when overweight. Overweight women (N = 126; 19-77 years of age, M = 47.2) filled out weekly questionnaires on the outcomes of behavioral, emotional, and cognitive self-regulation during a dieting program; outcomes included deviations from the diet, weight loss, affect, and rumination. Confirming hypotheses, multilevel analyses revealed that - even after controlling for prior dieting attempts - age was associated with better self-reported self-regulation (i.e., fewer deviations from the diet, lower disinhibition and rumination after failure, and higher affective well-being) but not with more weight loss. Results suggest that self-regulation improves with age and shows positive effects on subjective indicators of successfully coping with setbacks but does not directly influence the target-outcome weight loss.
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Effect of street connectivity and density on adult BMI: results from the Twin Cities Walking Study
Kelsey McDonald, Michael Oakes & Ann Forsyth
Journal of Epidemiology and Community Health, forthcoming
Background: The prevalence of overweight and obesity in the US population has risen dramatically in recent years. To try to explain this, some studies have examined the association between the built environment and obesity (measured using the body mass index (BMI)). Most of these studies have not sought to identify causal effects, but rather correlations.
Methods: Data from the Twin Cities Walking Study were used to examine the effect of population density and block size on BMI. Although the Twin Cities Walking Study is a cross-sectional observational study, the matched-sampling design is novel in that it maximises environmental variance while minimising person variance to enhance exchangeability of subjects and more closely mimic an experimental study.
Results: Contrary to expectations, the hypothesised most walkable neighbourhood (high density, small block stratum) had the greatest mean and median BMI. After adjusting for demographic covariates, physical activity and clustering due to neighbourhood, no conclusive effect of population density by block size on BMI was found (β=-1.024, 95% CI -2.408 to 0.359).
Conclusion: There is no evidence of an effect of population density by block size on BMI.
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Caloric Restriction Experience Reprograms Stress and Orexigenic Pathways and Promotes Binge Eating
Diana Pankevich et al.
Journal of Neuroscience, 1 December 2010, Pages 16399-16407
Abstract:
Long-term weight management by dieting has a high failure rate. Pharmacological targets have focused on appetite reduction, although less is understood as to the potential contributions of the stress state during dieting in long-term behavioral modification. In a mouse model of moderate caloric restriction in which a 10-15% weight loss similar to human dieting is produced, we examined physiological and behavioral stress measures. After 3 weeks of restriction, mice showed significant increases in immobile time in a tail suspension test and stress-induced corticosterone levels. Increased stress was associated with brain region-specific alterations of corticotropin-releasing factor expression and promoter methylation, changes that were not normalized with refeeding. Similar outcomes were produced by high-fat diet withdrawal, an additional component of human dieting. In examination of long-term behavioral consequences, previously restricted mice showed a significant increase in binge eating of a palatable high-fat food during stress exposure. Orexigenic hormones, melanin-concentrating hormone (MCH) and orexin, were significantly elevated in response to the high-fat diet only in previously restricted mice. Furthermore, administration of the MCH receptor-1 antagonist GSK-856464 [4-(4-ethyl-5-methylsulfanyl-1,2,4-triazol-3-yl)pyridine] significantly reduced total caloric intake in these mice during high-fat access. These results reveal reprogramming of key central pathways involved in regulating stress responsivity and orexigenic drives by moderate caloric restriction experience. In humans, such changes would be expected to reduce treatment success by promoting behaviors resulting in weight regain, and suggest that management of stress during dieting may be beneficial in long-term maintenance.
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HPA axis dampening by limited sucrose intake: Reward frequency vs. caloric consumption
Yvonne Ulrich-Lai, Michelle Ostrander & James Herman
Physiology & Behavior, forthcoming
Abstract:
Individuals often cope with stress by consuming calorically-dense, highly-palatable "comfort" foods. The present work explores the stress-relieving properties of palatable foods in a rat model of limited sucrose intake. In this model, adult male rats with free access to chow and water are given additional access to a small amount of sucrose drink (or water as a control). A history of such limited sucrose intake reduces the collective (HPA axis, sympathetic, and behavioral-anxiety) stress response. Moreover, the stress-dampening by sucrose appears to be mediated primarily by its rewarding properties, since beneficial effects are reproduced by the noncaloric sweetener saccharin but not oral intragastric gavage of sucrose. The present work uses an alternate strategy to address the hypothesis that the rewarding properties of sucrose mediate its stress-dampening. This work varies the duration, frequency, and/or volume of sucrose and assesses the ability to attenuate HPA axis stress responses. The data indicate that HPA-dampening is optimal with a greater duration and/or frequency of sucrose, whereas increasing the volume of sucrose consumed is without effect. This finding suggests that the primary factor mediating stress-dampening is the number/rate of reward (i.e., sucrose) exposures, rather than the total sucrose calories consumed. Collectively, these data support the hypothesis that stress relief by limited palatable food intake is mediated primarily by its hedonic/rewarding properties. Moreover, the results support the contention that naturally rewarding behaviors are a physiological means to produce stress relief.