Size Matters
Why are educated adults slim — causation or selection?
Paul von Hippel & Jamie Lynch
Social Science & Medicine, forthcoming
Abstract:
More educated adults tend to have lower body mass index (BMI) and a lower risk of overweight and obesity. We contrast two explanations for this education gradient in BMI. One explanation is selection: adolescents with high BMI are less likely to plan for, attend, and complete higher levels of education. An alternative explanation is causation: higher education confers lifelong social, economic, and psychological benefits that help adults to restrain BMI growth. We test the relative importance of selection and causation using data from the National Longitudinal Survey of Youth, 1997 cohort (NLSY97), which tracks BMI from adolescence (age 15) through young adulthood (age 29). Ordinal regression models confirm the selection hypothesis that high-BMI adolescents are less likely to complete higher levels of education. Selection has primarily to do with the fact that high-BMI adolescents tend to come from socioeconomically disadvantaged families and tend to have low grades and test scores. Among high-BMI girls there is also some evidence that educational attainment is limited by bullying, pessimism, poor health, and early pregnancy. About half the selection of high-BMI girls out of higher education remains unexplained. Fixed-effects models control for selection and suggest that the causal effect of education on BMI, though significant, accounts for only one-quarter of the mean BMI differences between more and less educated adults at age 29. Among young adults, it appears that most of the education gradient in BMI is due to selection.
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Increasing socioeconomic disparities in adolescent obesity
Carl Frederick, Kaisa Snellman & Robert Putnam
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Recent reports suggest that the rapid growth in youth obesity seen in the 1980s and 1990s has plateaued. We examine changes in obesity among US adolescents aged 12–17 y by socioeconomic background using data from two nationally representative health surveys, the 1988–2010 National Health and Nutrition Examination Surveys and the 2003–2011 National Survey of Children’s Health. Although the overall obesity prevalence stabilized, this trend masks a growing socioeconomic gradient: The prevalence of obesity among high-socioeconomic status adolescents has decreased in recent years, whereas the prevalence of obesity among their low-socioeconomic status peers has continued to increase. Additional analyses suggest that socioeconomic differences in the levels of physical activity, as well as differences in calorie intake, may have contributed to the growing obesity gradient.
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Financial Hardship and Obesity
Susan Averett & Julie Smith
Economics & Human Biology, forthcoming
Abstract:
There is a substantial correlation between household debt and health. Individuals with less healthy lifestyles are more likely to hold debt, yet there is little evidence as to whether this is merely a correlation or if financial hardship actually causes obesity. In this paper, we use data from the National Longitudinal Survey of Adolescent Health to test whether financial hardship affects body weight. We divide our sample into two groups: men and women, explore two different types of financial hardship: holding credit card debt and having trouble paying bills, and three outcomes: overweight, obese and Body Mass Index (BMI). We use a variety of econometric techniques: Ordinary Least Squares, Propensity Score Matching, Sibling Fixed Effects, and Instrumental Variables to investigate the relationship that exists between financial hardship and body weight. In addition, we conduct several robustness checks. Although our OLS and PSM results indicate a correlation between financial hardship and body weight these results appear to be largely driven by unobservables. Our IV results suggest that there is no causal relationship between credit card debt and overweight or obesity for either men or women. However, we find suggestive evidence that having trouble paying bills may be a cause of obesity for women.
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Pass the popcorn: “Obesogenic” behaviors and stigma in children's movies
Elizabeth Throop et al.
Obesity, forthcoming
Objective: To determine the prevalence of obesity-related behaviors and attitudes in children's movies.
Design and Methods: A mixed-methods study of the top-grossing G- and PG-rated movies, 2006-2010 (4 per year) was performed. For each 10-min movie segment, the following were assessed: 1) prevalence of key nutrition and physical activity behaviors corresponding to the American Academy of Pediatrics obesity prevention recommendations for families; 2) prevalence of weight stigma; 3) assessment as healthy, unhealthy, or neutral; 3) free-text interpretations of stigma.
Results: Agreement between coders was >85% (Cohen's kappa = 0.7), good for binary responses. Segments with food depicted: exaggerated portion size (26%); unhealthy snacks (51%); sugar-sweetened beverages (19%). Screen time was also prevalent (40% of movies showed television; 35% computer; 20% video games). Unhealthy segments outnumbered healthy segments 2:1. Most (70%) of the movies included weight-related stigmatizing content (e.g., “That fat butt! Flabby arms! And this ridiculous belly!”).
Conclusions: These popular children's movies had significant “obesogenic” content, and most contained weight-based stigma. They present a mixed message to children, promoting unhealthy behaviors while stigmatizing the behaviors' possible effects. Further research is needed to determine the effects of such messages on children.
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Influencing Food Choices by Training: Evidence for Modulation of Frontoparietal Control Signals
Tom Schonberg et al.
Journal of Cognitive Neuroscience, February 2014, Pages 247-268
Abstract:
To overcome unhealthy behaviors, one must be able to make better choices. Changing food preferences is an important strategy in addressing the obesity epidemic and its accompanying public health risks. However, little is known about how food preferences can be effectively affected and what neural systems support such changes. In this study, we investigated a novel extensive training paradigm where participants chose from specific pairs of palatable junk food items and were rewarded for choosing the items with lower subjective value over higher value ones. In a later probe phase, when choices were made for real consumption, participants chose the lower-valued item more often in the trained pairs compared with untrained pairs. We replicated the behavioral results in an independent sample of participants while they were scanned with fMRI. We found that, as training progressed, there was decreased recruitment of regions that have been previously associated with cognitive control, specifically the left dorsolateral pFC and bilateral parietal cortices. Furthermore, we found that connectivity of the left dorsolateral pFC was greater with primary motor regions by the end of training for choices of lower-valued items that required exertion of self-control, suggesting a formation of a stronger stimulus–response association. These findings demonstrate that it is possible to influence food choices through training and that this training is associated with a decreasing need for top–down frontoparietal control. The results suggest that training paradigms may be promising as the basis for interventions to influence real-world food preferences.
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Spatial Mobility and Environmental Effects on Obesity
Zhenxiang Zhao, Robert Kaestner & Xin Xu
Economics & Human Biology, forthcoming
Abstract:
In this paper, we used a randomized experiment, the Moving to Opportunity for Fair Housing Demonstration (MTO) study, to assess whether several environmental attributes are causes of obesity. To accomplish our objective, we linked the MTO data with several external data sources that provide information on potential determinants of obesity including food prices, restaurant and food store availability, physical activity facility availability, the prevalence of crime and population density. We find that the environmental factors we examined are unable to explain the observed decrease in obesity associated with the MTO experiment among low-income minority women.
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Maddalena Marini et al.
PLoS ONE, December 2013
Abstract:
Although a greater degree of personal obesity is associated with weaker negativity toward overweight people on both explicit (i.e., self-report) and implicit (i.e., indirect behavioral) measures, overweight people still prefer thin people on average. We investigated whether the national and cultural context – particularly the national prevalence of obesity – predicts attitudes toward overweight people independent of personal identity and weight status. Data were collected from a total sample of 338,121 citizens from 71 nations in 22 different languages on the Project Implicit website (https://implicit.harvard.edu/) between May 2006 and October 2010. We investigated the relationship of the explicit and implicit weight bias with the obesity both at the individual (i.e., across individuals) and national (i.e., across nations) level. Explicit weight bias was assessed with self-reported preference between overweight and thin people; implicit weight bias was measured with the Implicit Association Test (IAT). The national estimates of explicit and implicit weight bias were obtained by averaging the individual scores for each nation. Obesity at the individual level was defined as Body Mass Index (BMI) scores, whereas obesity at the national level was defined as three national weight indicators (national BMI, national percentage of overweight and underweight people) obtained from publicly available databases. Across individuals, greater degree of obesity was associated with weaker implicit negativity toward overweight people compared to thin people. Across nations, in contrast, a greater degree of national obesity was associated with stronger implicit negativity toward overweight people compared to thin people. This result indicates a different relationship between obesity and implicit weight bias at the individual and national levels.
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Body-mass index and mortality risk in US blacks compared to whites
Chandra Jackson et al.
Obesity, forthcoming
Objective: To compare body-mass index (BMI)-related mortality risk in US Blacks vs. Whites as the relationship appears to differ across race/ethnicity groups.
Design and Methods: We pooled cross-sectional surveys of nationally representative samples of 11,934 Blacks and 59,741 Whites aged 35-75 in the National Health Interview Survey from 1997-2002 with no history of cardiovascular disease or cancer. Mortality follow-up was available through 2006. BMI was calculated from self-reported height and weight. We used adjusted Cox regression analysis to adjust for potential confounders.
Results: Over 9 years of follow-up, there were 4,303 deaths (1,205 among never smokers). Age-adjusted mortality rates were higher in Blacks compared to Whites at BMI < 25 kg/m2 and showed no increase at higher levels of BMI. In men, adjusted hazard ratios for all-cause death rose in a similar fashion across upper BMI quintiles in Blacks and Whites; in women, however, BMI was positively associated with mortality risk in Whites, but inversely associated in Blacks (p interaction = 0.01). Racial disparities were amplified in subsidiary analyses that introduced a 12-month lag for mortality or focused on CVD mortality.
Conclusions: The relationship of elevated BMI to mortality appears weaker in US Blacks than in Whites, especially among women.
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Qian Xiao et al.
Obesity, January 2014, Pages 260–268
Objective: In a large prospective cohort, we examined the relationship of body mass index (BMI) with mortality among blacks and compared the results to those among whites in this population.
Design and Methods: The study population consisted of 7,446 non-Hispanic black and 130,598 white participants, ages 49-78 at enrollment, in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. BMI at baseline, BMI at age 20, and BMI change were calculated using self-reported and recalled height and weight. Relative risks were stratified by race and sex and adjusted for age, education, marital status, and smoking.
Results: During follow-up, 1,495 black and 18,236 white participants died (mean = 13 years). Clear J-shaped associations between BMI and mortality were observed among white men and women. Among black men and women, the bottoms of these curves were flatter, and increasing risks of death with greater BMI were observed only at higher BMI levels (≥35.0). Associations for BMI at age 20 and BMI change also appeared to be stronger in magnitude in whites versus blacks, and these racial differences appeared to be more pronounced among women.
Conclusion: Our results suggest that BMI may be more weakly associated with mortality in blacks, particularly black women, than in whites.
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Kiarri Kershaw et al.
American Journal of Epidemiology, forthcoming
Abstract:
Few studies have examined longitudinal associations between close social relationships and weight change. Using data from 3,074 participants in the Coronary Artery Risk Development in Young Adults Study who were examined in 2000, 2005, and 2010 (at ages 33–45 years in 2000), we estimated separate logistic regression random-effects models to assess whether patterns of exposure to supportive and negative relationships were associated with 10% or greater increases in body mass index (BMI) (weight (kg)/height (m)2) and waist circumference. Linear regression random-effects modeling was used to examine associations of social relationships with mean changes in BMI and waist circumference. Participants with persistently high supportive relationships were significantly less likely to increase their BMI values and waist circumference by 10% or greater compared with those with persistently low supportive relationships after adjustment for sociodemographic characteristics, baseline BMI/waist circumference, depressive symptoms, and health behaviors. Persistently high negative relationships were associated with higher likelihood of 10% or greater increases in waist circumference (odds ratio = 1.62, 95% confidence interval: 1.15, 2.29) and marginally higher BMI increases (odds ratio = 1.50, 95% confidence interval: 1.00, 2.24) compared with participants with persistently low negative relationships. Increasingly negative relationships were associated with increases in waist circumference only. These findings suggest that supportive relationships may minimize weight gain, and that adverse relationships may contribute to weight gain, particularly via central fat accumulation.
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Daphne Hernandez & Emily Pressler
Journal of Epidemiology & Community Health, forthcoming
Background: Childhood poverty is positively correlated with overweight status during childhood, adolescence and adulthood. Repeated exposure of childhood poverty could contribute to race/ethnicity and gender disparities in young adult overweight/obese (OV/OB) weight status.
Methods: Young adults born between 1980 and 1990 who participated in the Young Adult file of the 1979 National Longitudinal Study of Youth were examined (N=3901). The accumulation of childhood poverty is captured via poverty exposure from each survey year from the prenatal year through age 18 years. Body mass index was calculated and categorised into the reference criteria for adults outlined by the Center for Disease Control. Logistic regression models were stratified by race/ethnicity and included a term interacting poverty and gender, along with a number of covariates, including various longitudinal socioeconomic status measures and indicators for the intergenerational transmission of economic disadvantage and body weight.
Results: Reoccurring exposure to childhood poverty was positively related to OV/OB for white, black and Hispanic young adult women and inversely related for white young adult men. A direct relationship between the accumulation of childhood poverty and OV/OB was not found for black and Hispanic young adult men.
Conclusions: Helping families move out of poverty may improve the long-term health status of white, black and Hispanic female children as young adults. Community area interventions designed to change impoverished community environments and assist low-income families reduce family level correlates of poverty may help to reduce the weight disparities observed in young adulthood.
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Jennifer Poti, Kiyah Duffey & Barry Popkin
American Journal of Clinical Nutrition, January 2014, Pages 162-171
Background: Although fast food consumption has been linked to adverse health outcomes, the relative contribution of fast food itself compared with the rest of the diet to these associations remains unclear.
Objective: Our objective was to compare the independent associations with overweight/obesity or dietary outcomes for fast food consumption compared with dietary pattern for the remainder of intake.
Design: This cross-sectional analysis studied 4466 US children aged 2–18 y from NHANES 2007–2010. Cluster analysis identified 2 dietary patterns for the non–fast food remainder of intake: Western (50.3%) and Prudent. Multivariable-adjusted linear and logistic regression models examined the association between fast food consumption and dietary pattern for the remainder of intake and estimated their independent associations with overweight/obesity and dietary outcomes.
Results: Half of US children consumed fast food: 39.5% low-consumers (≤30% of energy from fast food) and 10.5% high-consumers (>30% of energy). Consuming a Western dietary pattern for the remainder of intake was more likely among fast food low-consumers (OR: 1.51; 95% CI: 1.24, 1.85) and high-consumers (OR: 2.21; 95% CI: 1.60, 3.05) than among nonconsumers. The remainder of diet was independently associated with overweight/obesity (β: 5.9; 95% CI: 1.3, 10.5), whereas fast food consumption was not, and the remainder of diet had stronger associations with poor total intake than did fast food consumption.
Conclusions: Outside the fast food restaurant, fast food consumers ate Western diets, which might have stronger associations with overweight/obesity and poor dietary outcomes than fast food consumption itself. Our findings support the need for prospective studies and randomized trials to confirm these hypotheses.
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Using Incentives to Encourage Healthy Eating in Children
David Just & Joseph Price
Journal of Human Resources, Fall 2013, Pages 855-872
Abstract:
There is growing interest in the situations in which incentives have a significant effect on positive behaviors, particularly in children. Using a randomized field experiment, we find that incentives increase the fraction of children eating a serving of fruits or vegetables during lunch by 80% and reduces the amount of waste by 33%. At schools with a larger fraction of low-income children, the increase in the fraction of children who eat a serving of fruits or vegetables is even larger, indicating that incentives successfully target the children who are likely to benefit the most from the increased consumption.
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A randomized trial comparing two approaches to weight loss: Differences in weight loss maintenance
Robert Carels et al.
Journal of Health Psychology, February 2014, Pages 296-311
Abstract:
This study compared treatment outcomes for a new weight loss program that emphasized reducing unhealthy relationships with food, body image dissatisfaction, and internalized weight bias (New Perspectives) to a weight loss program that emphasizes environmental modification and habit formation and disruption (Transforming Your Life). Fifty-nine overweight and obese adults (body mass index ≥ 27 kg/m2) were randomly assigned to either a 12-week New Perspectives or Transforming Your Life intervention. Despite equivalent outcomes at the end of treatment, the Transforming Your Life participants were significantly more effective at maintaining their weight loss than New Perspectives participants during the 6-month no-treatment follow-up period.
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Is overweight and class I obesity associated with increased health claims costs?
Truls Østbye et al.
Obesity, forthcoming
Objectives: Evaluate the relationship between body mass index (BMI) and health claims costs over the last decade, assess the strength and nature of the relationship between BMI and costs, and identify comorbidities that may drive any increased costs.
Design and Methods: Using 2001-2011 claims data for employees participating in annual health appraisals, annual paid claims costs were calculated. One-part negative binomial models were fit to evaluate the relationship between BMI and costs, controlling for age, gender, race/ethnicity, and calendar year period.
Results: The relationship between increasing BMI and increasing health claims costs is gradual and starts already at a BMI of 19. The nature of the relationship did not change notably over time. The most important obesity-related comorbidities, expressed as percent increase in cost per BMI unit, was cardiovascular disease (males 10.53, 95% CI [6.46, 14.77], females 4.27, 95% CI [1.25, 7.38), while cardiovascular agents (7.23, 95% CI [6.08, 8.39]) were the most important driver of pharmacy costs.
Conclusion: In contrast to recent evidence relating to effects on mortality, we observed a gradual increase in health claims costs starting at the low end of the recommended BMI range.
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The Stress of Stigma: Exploring the Effect of Weight Stigma on Cortisol Reactivity
Natasha Schvey, Rebecca Puhl & Kelly Brownell
Psychosomatic Medicine, forthcoming
Objective: To determine the physiological impact of exposure to weight stigma by examining alterations in salivary cortisol among lean and overweight women.
Methods: Participants were 123 lean and overweight adult women (mean body mass index = 26.99 [7.91] kg/m2). Participants’ salivary cortisol was assessed both before and after either a weight stigmatizing or a neutral video. Participants completed self-report measures of mood and reactions to the video. Height and weight were obtained at the conclusion of the study.
Results: Participants in the stigmatizing condition exhibited significantly greater cortisol reactivity when compared with those in the neutral condition, irrespective of weight status (Pillai trace = 0.077; F(1,85) = 7.22, p = .009). Lean and overweight women in the stigmatizing condition were equally likely to find the video upsetting and were equally likely to report that they would rather not see obese individuals depicted in a stigmatizing manner in the media.
Conclusions: Exposure to weight-stigmatizing stimuli was associated with greater cortisol reactivity among lean and overweight women. These findings highlight the potentially harmful physiological consequences of exposure to weight stigma.
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Increased Scalp Hair Cortisol Concentrations in Obese Children
Margriet Veldhorst et al.
Journal of Clinical Endocrinology & Metabolism, January 2014, Pages 285-290
Context: Pathologically increased cortisol exposure induces obesity, but it is not known whether relatively high cortisol within the physiological range is related to childhood obesity.
Objective: The aim of the study was to compare hair cortisol concentrations between obese and normal-weight children.
Design: We performed an observational case-control study.
Participants: Twenty obese children (body mass index-SD score [BMI-SDS] > 2.3) and 20 age- and sex-matched normal-weight children (BMI-SDS < 1.1) aged 8–12 years were recruited.
Main Outcome Measures: Scalp hair samples from the posterior vertex were collected, and hair cortisol concentrations were measured using ELISA. Body weight, height, and waist circumference were measured. From the obese children, additional data on blood pressure and blood lipid concentrations were collected.
Results: In both groups, five boys and 15 girls were included; their mean age was 10.8 ± 1.3 vs 10.8 ± 1.2 years (obese vs normal weight; not significant). Body weight, BMI, BMI-SDS, and waist circumference were higher in the obese children compared with the normal-weight children (69.8 ± 17.2 vs 35.5 ± 7.2 kg; 29.6 ± 4.9 vs 16.4 ± 1.6 kg/m2; 3.4 ± 0.5 vs −0.2 ± 0.8 SDS; 94 ± 13 vs 62 ± 6 cm; P < .001 all). Hair cortisol concentration was higher in obese than normal-weight children (median [interquartile range], 25 [17, 32] vs 17 [13, 21] pg/mg; P < .05).
Conclusions: Hair cortisol concentration, a measure for long-term cortisol exposure, was higher in obese children than normal-weight children. This suggests long-term activation of the hypothalamus-pituitary-adrenal axis in obese children and may provide a novel target for treatment of obesity in children.
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Sean Phelan et al.
Obesity, forthcoming
Objective: To examine the magnitude of explicit and implicit weight biases compared to biases against other groups; and identify student factors predicting bias in a large national sample of medical students.
Design and Methods: A web-based survey was completed by 4732 1st year medical students from 49 medical schools as part of a longitudinal study of medical education. The survey included a validated measure of implicit weight bias, the implicit association test, and 2 measures of explicit bias: a feeling thermometer and the anti-fat attitudes test.
Results: A majority of students exhibited implicit (74%) and explicit (67%) weight bias. Implicit weight bias scores were comparable to reported bias against racial minorities. Explicit attitudes were more negative toward obese people than toward racial minorities, gays, lesbians, and poor people. In multivariate regression models, implicit and explicit weight bias was predicted by lower BMI, male sex, and non-Black race. Either implicit or explicit bias was also predicted by age, SES, country of birth, and specialty choice.
Conclusions: Implicit and explicit weight bias is common among 1st year medical students, and varies across student factors. Future research should assess implications of biases and test interventions to reduce their impact.
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Brian Wansink & Koert van Ittersum
Journal of Experimental Psychology: Applied, December 2013, Pages 320-332
Abstract:
Research on the self-serving of food has empirically ignored the role that visual consumption norms play in determining how much food we serve on different sized dinnerware. We contend that dinnerware provides a visual anchor of an appropriate fill-level, which in turn, serves as a consumption norm (Study 1). The trouble with these dinnerware-suggested consumption norms is that they vary directly with dinnerware size — Study 2 shows Chinese buffet diners with large plates served 52% more, ate 45% more, and wasted 135% more food than those with smaller plates. Moreover, education does not appear effective in reducing such biases. Even a 60-min, interactive, multimedia warning on the dangers of using large plates had seemingly no impact on 209 health conference attendees, who subsequently served nearly twice as much food when given a large buffet plate 2 hr later (Study 3). These findings suggest that people may have a visual plate-fill level — perhaps 70% full — that they anchor on when determining the appropriate consumption norm and serving themselves. Study 4 suggests that the Delboeuf illusion offers an explanation why people do not fully adjust away from this fill-level anchor and continue to be biased across a large range of dishware sizes. These findings have surprisingly wide-ranging win–win implications for the welfare of consumers as well as for food service managers, restaurateurs, packaged goods managers, and public policy officials.
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The Effect of Prices on Nutrition: Comparing the Impact of Product- and Nutrient-Specific Taxes
Matthew Harding & Michael Lovenheim
NBER Working Paper, January 2014
Abstract:
This paper provides an analysis of the role of prices in determining food purchases and nutrition using very detailed transaction-level observations for a large, nationally-representative sample of US consumers over the period 2002-2007. Using product- specific nutritional information, we develop a new method of partitioning the product space into relevant nutritional clusters that define a set of nutritionally-bundled goods, which parsimoniously characterize consumer choice sets. We then estimate a large utility-derived demand system over this joint product-nutrient space that allows us to calculate price and expenditure elasticities. Using our structural demand estimates, we simulate the role of product taxes on soda, sugar-sweetened beverages, packaged meals, and snacks, and nutrient taxes on fat, salt, and sugar. We find that a 20% nutrient tax has a significantly larger impact on nutrition than an equivalent product tax, due to the fact that these are broader-based taxes. However, the costs of these taxes in terms of consumer utility are not higher. A sugar tax in particular is a powerful tool to induce healthier nutritive bundles among consumers.
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Life Years Lost Associated with Obesity-Related Diseases for U.S. Non-Smoking Adults
Su-Hsin Chang, Lisa Pollack & Graham Colditz
PLoS ONE, June 2013
Abstract:
The objectives of this paper are to predict life years lost associated with obesity-related diseases (ORDs) for U.S. non-smoking adults, and to examine the relationship between those ORDs and mortality. Data from the National Health Interview Survey, 1997–2000, were used. We employed mixed proportional hazard models to estimate the association between those ORDs and mortality and used simulations to project life years lost associated with the ORDs. We found that obesity-attributable comorbidities are associated with large decreases in life years and increases in mortality rates. The life years lost associated with ORDs is more marked for younger adults than older adults, for blacks than whites, for males than females, and for the more obese than the less obese. Using U.S. non-smoking adults aged 40 to 49 years as an example to illustrate percentage of the life years lost associated with ORDs, we found that the mean life years lost associated with ORDs for U.S. non-smoking black males aged 40 to 49 years with a body mass index above 40 kg/m2 was 5.43 years, which translates to a 7.5% reduction in total life years. White males of the same age range and same degree of obesity lost 5.23 life years on average – a 6.8% reduction in total life years, followed by black females (5.04 years, a 6.5% reduction in life years), and white females (4.7 years, a 5.8% reduction in life years). Overall, ORDs increased chances of dying and lessened life years by 0.2 to 11.7 years depending on gender, race, BMI classification, and age.
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Janne Boone-Heinonen et al.
PLoS ONE, December 2013
Background: Recent obesity prevention initiatives focus on healthy neighborhood design, but most research examines neighborhood food retail and physical activity (PA) environments in isolation. We estimated joint, interactive, and cumulative impacts of neighborhood food retail and PA environment characteristics on body mass index (BMI) throughout early adulthood.
Methods and Findings: We used cohort data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study [n=4,092; Year 7 (24-42 years, 1992-1993) followed over 5 exams through Year 25 (2010-2011); 12,921 person-exam observations], with linked time-varying geographic information system-derived neighborhood environment measures. Using regression with fixed effects for individuals, we modeled time-lagged BMI as a function of food and PA resource density (counts per population) and neighborhood development intensity (a composite density score). We controlled for neighborhood poverty, individual-level sociodemographics, and BMI in the prior exam; and included significant interactions between neighborhood measures and by sex. Using model coefficients, we simulated BMI reductions in response to single and combined neighborhood improvements. Simulated increase in supermarket density (from 25th to 75th percentile) predicted inter-exam reduction in BMI of 0.09 kg/m2 [estimate (95% CI): -0.09 (-0.16, -0.02)]. Increasing commercial PA facility density predicted BMI reductions up to 0.22 kg/m2 in men, with variation across other neighborhood features [estimate (95% CI) range: -0.14 (-0.29, 0.01) to -0.22 (-0.37, -0.08)]. Simultaneous increases in supermarket and commercial PA facility density predicted inter-exam BMI reductions up to 0.31 kg/m2 in men [estimate (95% CI) range: -0.23 (-0.39, -0.06) to -0.31 (-0.47, -0.15)] but not women. Reduced fast food restaurant and convenience store density and increased public PA facility density and neighborhood development intensity did not predict reductions in BMI.
Conclusions: Findings suggest that improvements in neighborhood food retail or PA environments may accumulate to reduce BMI, but some neighborhood changes may be less beneficial to women.
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Demand for food-away-from-home: A multiple-discrete–continuous extreme value model
Timothy Richards & Lisa Mancino
European Review of Agricultural Economics, February 2014, Pages 111-133
Abstract:
Policymakers have suggested the use of taxes to raise the relative cost of buying fast food. Yet, little is known of the structure of demand for food-away-from-home (FAFH) in general. This study provides estimates of the price-elasticity of demand for four different types of FAFH using a new data set from NPD, Inc. and an econometric approach that accounts for the multiple-discrete–continuous nature of FAFH demand. We find that cross-price elasticities of demand are small, so consumers are unwilling to substitute between food-at-home and any type of FAFH or among types of FAFH. Therefore, taxing fast food may be effective in reducing the number of fast food visits and shifting consumption to at-home meals.
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Warren Bickel et al.
Appetite, forthcoming
Abstract:
Previous research comparing obese and non-obese samples on the delayed discounting procedure has produced mixed results. The aim of the current study was to clarify these discrepant findings by comparing a variety of temporal discounting measures in a large sample of internet users (n = 1163) obtained from a crowdsourcing service, Amazon Mechanical Turk (AMT). Measures of temporal, social–temporal (a combination of standard and social temporal), and probability discounting were obtained. Significant differences were obtained on all discounting measures except probability discounting, but the obtained effect sizes were small. These data suggest that larger-N studies will be more likely to detect differences between obese and non-obese samples, and may afford the opportunity, in future studies, to decompose a large obese sample into different subgroups to examine the effect of other relevant measures, such as the reinforcing value of food, on discounting.