All Consuming
Thought for Food: Imagined Consumption Reduces Actual Consumption
Carey Morewedge, Young Eun Huh & Joachim Vosgerau
Science, 10 December 2010, Pages 1530-1533
Abstract:
The consumption of a food typically leads to a decrease in its subsequent intake through habituation-a decrease in one's responsiveness to the food and motivation to obtain it. We demonstrated that habituation to a food item can occur even when its consumption is merely imagined. Five experiments showed that people who repeatedly imagined eating a food (such as cheese) many times subsequently consumed less of the imagined food than did people who repeatedly imagined eating that food fewer times, imagined eating a different food (such as candy), or did not imagine eating a food. They did so because they desired to eat it less, not because they considered it less palatable. These results suggest that mental representation alone can engender habituation to a stimulus.
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Chad Meyerhoefer & Ephraim Leibtag
American Journal of Agricultural Economics, October 2010, Pages 1271-1282
Abstract:
We investigate the impact of changes in the relative price of low- and high-carbohydrate foods on medical expenditures for diabetes care using Nielsen Homescan price data merged to the 2000-2005 Medical Expenditure Panel Survey. We find that an increase in low-(high-)carbohydrate food price increases (decreases) both the likelihood of a diabetes diagnosis and the level of medical expenditures among those with diabetes. We also find small impacts of food prices on body mass index that differ by gender. Policy simulations suggest that subsidizing the low-carbohydrate food purchases of people with diabetes could result in significant reductions in health care costs.
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Snacking while watching TV impairs food recall and promotes food intake on a later TV free test meal
Dolly Mittal, Richard Stevenson, Megan Oaten & Laurie Miller
Applied Cognitive Psychology, forthcoming
Abstract:
Eating while viewing TV may impair memory of food intake and promote over-consumption on a later meal. In Experiment 1, females ate a similar amount of snack-food either with or without TV. Later, participants who had snacked with TV ate more food on a TV-free lunch and were less accurate in recalling their earlier snack-food intake. Experiment 2 explored whether the nature of the TV content might alter these effects. Using a similar design, females watched boring, sad or funny TV, or no-TV at all. Relative to the no-TV control, all TV while snacking conditions ate a similarly greater amount on the later TV-free test lunch. Recall accuracy for the snack phase was also similarly poorer in all TV conditions. These findings suggest that eating with TV per se impacts on later food intake, and a mnemonic-based explanation seems to be the best account for these findings.
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Is Poor Fitness Contagious? Evidence from Randomly Assigned Friends
Scott Carrell, Mark Hoekstra & James West
NBER Working Paper, November 2010
Abstract:
The increase in obesity over the past thirty years has led researchers to investigate the role of social networks as a contributing factor. However, several challenges make it difficult to demonstrate a causal link between friends' physical fitness and own fitness using observational data. To overcome these problems, we exploit data from a unique setting in which individuals are randomly assigned to peer groups. We find statistically significant peer effects that are 40 to 70 percent as large as the own effect of prior fitness scores on current fitness outcomes. Evidence suggests that the effects are caused primarily by friends who were the least fit, thus supporting the provocative notion that poor physical fitness spreads on a person-to-person basis.
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Impaired decision making among morbidly obese adults
Amy Brogan, David Hevey, Georgia O'Callaghan, Ruth Yoder & Donal O'Shea
Journal of Psychosomatic Research, forthcoming
Objective: The Iowa Gambling Task (IGT) measures affective decision making and has revealed decision making impairments across a wide range of eating disorders. This study aimed to investigate affective decision making in severely obese individuals.
Methods: Forty-two (12 male, 30 female) morbidly obese participants (mean BMI=41.45) and 50 comparison participants (17 male, 33 female) matched for age, gender and education, completed the IGT.
Results: Obese participants performed significantly worse on the IGT compared to the comparison group, with 69% of the obese group demonstrating clinically impaired decision making. There was no evidence of learning across the five trial blocks in obese participants, with significant differences between the groups emerging in blocks 3, 4, and 5. IGT impairment was unrelated to BMI or eating pathology.
Conclusion: Obese participants were significantly impaired on the IGT. The pattern of performance suggested a potential inability to maximise an immediate reward or program a delayed reward. The findings support the view that common decision making impairments exist across disordered eating populations. Future research is required to specify the source and mechanisms of these decision making deficits. The logical progression of this research is the development of interventions which improve decision making capacity and measure subsequent impact on psychological and physical outcomes.
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Are socio-economic disparities in diet quality explained by diet cost?
Pablo Monsivais, Anju Aggarwal & Adam Drewnowski
Journal of Epidemiology and Community Health, forthcoming
Background: Socio-economic disparities in nutrition are well documented. This study tested the hypothesis that socio-economic differences in nutrient intakes can be accounted for, in part, by diet cost.
Methods: A representative sample of 1295 adults in King County (WA) was surveyed in 2008-2009, and usual dietary intakes were assessed based on a food-frequency questionnaire. The monetary value of individual diets was estimated using local retail supermarket prices for 384 foods. Nutrients of concern as identified by the 2005 Dietary Guidelines Advisory Committee were fibre, vitamins A, C and E, calcium, magnesium and potassium. A nutrient density score based on all seven nutrients was another dependent measure. General linear models and linear regressions were used to examine associations among education and income, nutrient density measure and diet cost. Analyses were conducted in 2009-2010.
Results: Controlling for energy and other covariates, higher-cost diets were significantly higher in all seven nutrients and in overall nutrient density. Higher education and income were positively and significantly associated with the nutrient density measure, but these effects were greatly attenuated with the inclusion of the cost variable in the model.
Conclusions: Socio-economic differences in nutrient intake can be substantially explained by the monetary cost of the diet. The higher cost of more nutritious diets may contribute to socio-economic disparities in health and should be taken into account in the formulation of nutrition and public health policy.
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Bree Dority, Mary McGarvey & Patricia Kennedy
Journal of Public Policy & Marketing, Fall 2010, Pages 204-218
Abstract:
Beginning with the 2006-2007 academic year, the U.S. government required that all federally funded schools have local wellness policies to promote healthful living and reduce obesity among their students; however, little evidence exists on which school food policies are effective. This article finds evidence that prohibiting à la carte junk food sales during meals reduces the likelihood that students will be overweight or obese by 18 percentage points. The data are merged student-parent-school survey responses collected from a small sample of schools in one Great Plains state. The estimation controls for students' activity levels, genetics, and socioeconomic factors; parents' activity levels and attitudes; and the overall mix of school marketing policies that promote healthful eating and drinking habits. The results indicate that banning à la carte junk food sales is a potentially effective policy to reduce the likelihood of students being overweight and obese.
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Does Early School Entry Prevent Obesity Among Adolescent Girls?
Ning Zhang & Qi Zhang
Journal of Adolescent Health, forthcoming
Purpose: To examine the relationship between early school entry and body weight status among adolescent girls.
Methods: Using nationally representative data from the 1997 cohort of the National Longitudinal Survey of Youth, we exploited state-specific first-grade entrance policy as a quasi-experimental research design to examine the effect of early school entry on the body weight status of adolescent girls. Fixed-effects models were used to compare the body mass index (BMI), BMI z-score, and likelihood of overweight and obesity between teenage girls born before school cut-off dates and those born after, while controlling for age, race/ethnicity, maternal education status, and maternal body weight status.
Results: Late starters had higher BMIs and a higher prevalence of overweight and obesity and the results were found to be consistent across age groups. Among girls whose birthdays were within 1 month of the cut-off dates, the coefficient of late starting was significantly positive (β = .311; p = .02), indicating that it might be correlated with weight gain in adolescence.
Conclusions: Early admission to a school environment might have a long-term protective effect in terms of adolescent girls' propensity to obesity. Future studies are needed to examine the effect of early school entry on the eating behavior and physical activities of adolescent girls.
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The selfish brain: Competition for energy resources
Achim Peters
American Journal of Human Biology, January/February 2011, Pages 29-34
Abstract:
Obesity and type 2 diabetes have become the major health problems in many industrialized countries. Here, I present the unconventional concept that a healthy organism maintains its systemic homeostasis by a "competent brain-pull", i.e., the brain's ability to properly demand glucose from the body, and that the underlying cause of obesity is "incompetent brain-pull." I describe the energy fluxes from the environment, through the body, toward the brain as the final consumer in a "supply chain" model. There is data-based support for the hypothesis, which states that under conditions of food abundance incompetent brain-pull will lead to build ups in the supply chain culminating in obesity and type 2 diabetes. There is also support for the related hypothesis, which states that under conditions of food deprivation, a competent brain-pull mechanism is indispensable for the continuation of the brain's high energy level. To experimentally determine how the competent brain-pull functions to demand for cerebral energy, healthy young men undergoing psychosocial stress were studied. It was found that the brain under stressful conditions demands for energy from the body by using a brain-pull mechanism, which is referred to as "cerebral insulin suppression" and in so doing it can satisfy its excessive needs during stress. This article gives an overview about the recent work on the "Selfish Brain" theory dealing with the maintenance of the cerebral and peripheral energy homeostasis.
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Reward, dopamine and the control of food intake: Implications for obesity
Nora Volkow, Gene-Jack Wang & Ruben Baler
Trends in Cognitive Sciences, forthcoming
Abstract:
The ability to resist the urge to eat requires the proper functioning of neuronal circuits involved in top-down control to oppose the conditioned responses that predict reward from eating the food and the desire to eat the food. Imaging studies show that obese subjects might have impairments in dopaminergic pathways that regulate neuronal systems associated with reward sensitivity, conditioning and control. It is known that the neuropeptides that regulate energy balance (homeostatic processes) through the hypothalamus also modulate the activity of dopamine cells and their projections into regions involved in the rewarding processes underlying food intake. It is postulated that this could also be a mechanism by which overeating and the resultant resistance to homoeostatic signals impairs the function of circuits involved in reward sensitivity, conditioning and cognitive control.
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In Fitness and Health? A Prospective Study of Changes in Marital Status and Fitness in Men and Women
Francisco Ortega, Wendy Brown, Duck-chul Lee, Meghan Baruth, Xuemei Sui & Steven Blair
American Journal of Epidemiology, forthcoming
Abstract:
The authors examined the prospective associations between marital status transitions and changes in fitness in men and women. Between 1987 and 2005, a total of 8,871 adults (6,900 men) aged 45.6 (standard deviation, 9.1) years were examined at the Cooper Clinic, Dallas, Texas; the median follow-up was ∼3 years. Marital transition categories (from single to married, married to divorced, divorced to remarried) were derived from self-reported marital status at baseline and follow-up. Fitness (maximal oxygen consumption) was assessed by a maximal treadmill test. Analyses were adjusted for baseline levels and changes in body mass index, physical activity, smoking, alcohol consumption, and major chronic diseases. Compared with the corresponding "control" groups (remaining single, married, or divorced), transitioning from being single to married was associated with a reduction in fitness in women (P = 0.03); divorce was associated with an increase in fitness in men (P = 0.04); and remarriage was associated with a reduction in fitness in men (P = 0.05). The authors conclude that the transitions to being married (from single to married or from divorced to remarried) are associated with a modest reduction, while divorce is associated with a modest increase in fitness levels in men. Study results suggest that these patterns may be different in women, but further research is required to confirm this.
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As Pleasure Unfolds: Hedonic Responses to Tempting Food
Wilhelm Hofmann et al.
Psychological Science, forthcoming
Abstract:
Why do chronic dieters often violate their dieting goals? One possibility is that they experience stronger hedonic responses to tempting food than normal eaters do. We scrutinized hedonic processing in dieters and normal eaters (a) by manipulating food preexposure and (b) by assessing both immediate and delayed hedonic responses to tempting food with an adapted affect-misattribution procedure. Without food preexposure, dieters showed less positive hedonic responses than normal eaters (Study 1). When preexposed to tempting-food stimuli, however, dieters exhibited more positive delayed hedonic responses than normal eaters (Studies 1 and 2). Furthermore, delayed hedonic responding was meaningfully related to self-reported power of food and state cravings (Study 2). These findings suggest that dieters experience difficulties in down-regulating hedonic affect when in a "hot" state and that self-regulation research may benefit from a greater emphasis on temporal dynamics rather than static differences.
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Larry Howard
Economics of Education Review, February 2011, Pages 157-176
Abstract:
This paper estimates models of the transitional effects of food insecurity experiences on children's non-cognitive performance in school classrooms using a panel of 4710 elementary students enrolled in 1st, 3rd, and 5th grade (1999-2003). In addition to an extensive set of child and household-level characteristics, we use information on U.S. counties to control for potential confounding effects of the local economic and noneconomic environment on children's household transitions between states of food insecurity and food security. The time horizon of our analysis affords insight into factors underlying children's formation of non-cognitive skills and the efficiency of classroom-based educational production in elementary school. Overall, we find significant negative developmental effects for children with food insecurity at home; and that children experiencing an early transition from food insecurity in 1st grade to food security in 3rd grade have even larger impairments that persist through 5th grade.
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Constriction in the Variety of Urban Food Pantry Donations by Private Individuals
Michèle Companion
Journal of Urban Affairs, December 2010, Pages 633-646
Abstract:
The urban poor face a number of health challenges, many linked to lack of sufficient and consistent access to nutritious foods. Social ecology models demonstrate the negative impacts of high food cost and limited availability in urban areas. These studies note that "food deserts" have a profound impact on physiological pathologies of urban poor populations. Food pantries are an understudied feature of these urban landscapes. To address this gap, this study surveys the contents of food pantry donations during the month of September 2008. Data demonstrate the socioeconomic impact of reductions of charitable food donations on the diets of the urban poor.
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Cue-Reactors: Individual Differences in Cue-Induced Craving after Food or Smoking Abstinence
Stephen Mahler & Harriet de Wit
PLoS ONE, November 2010, e15475
Background: Pavlovian conditioning plays a critical role in both drug addiction and binge eating. Recent animal research suggests that certain individuals are highly sensitive to conditioned cues, whether they signal food or drugs. Are certain humans also more reactive to both food and drug cues?
Methods: We examined cue-induced craving for both cigarettes and food, in the same individuals (n = 15 adult smokers). Subjects viewed smoking-related or food-related images after abstaining from either smoking or eating.
Results: Certain individuals reported strong cue-induced craving after both smoking and food cues. That is, subjects who reported strong cue-induced craving for cigarettes also rated stronger cue-induced food craving.
Conclusions: In humans, like in nonhumans, there may be a "cue-reactive" phenotype, consisting of individuals who are highly sensitive to conditioned stimuli. This finding extends recent reports from nonhuman studies. Further understanding this subgroup of smokers may allow clinicians to individually tailor therapies for smoking cessation.
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Obesity-mediated inflammation may damage the brain circuit that regulates food intake
Fanny Cazettes, Jessica Cohen, Po Lai Yau, Hugues Talbot & Antonio Convit
Brain Research, forthcoming
Abstract:
Adiposity is associated with chronic low-grade systemic inflammation and increased inflammation in the hypothalamus, a key structure in feeding behavior. It remains unknown whether inflammation impacts other brain structures that regulate feeding behavior. We studied 44 overweight/obese and 19 lean individuals with MRI and plasma fibrinogen levels (marker of inflammation). We performed MRI-based segmentations of the medial and lateral orbitofrotal cortex (OFC) and hippocampal volumes. Gray matter (GM) volumes were adjusted for head size variability. We conducted logistic and hierarchical regressions to assess the association between fibrinogen levels and brain volumetric data. Using diffusion tensor imaging (DTI), we created apparent diffusion coefficient (ADC) maps and conducted voxelwise correlational analyses. Fibrinogen concentrations were higher among the overweight/obese (t[61]=-2.33, P=0.023). Lateral OFC associated together with fibrinogen correctly classified those with excess of weight (accuracy=76.2%, sensitivity=95.5%, specificity=31.6%). The lateral OFC volumes of overweight/obese were negatively associated with fibrinogen (r=-0.37, P=0.016) and after accounting for age, hypertension, waist/hip ratio and lipid and sugar levels, fibrinogen significantly explained an additional 9% of the variance in the lateral OFC volume (β=-0.348, ΔR2=0.093, ΔF P=0.046). Among overweight/obese the associations between GM ADC and fibrinogen were significantly positive (P<0.001) in the left and right amygdala and the right parietal region. Among lean individuals these associations were negative and located in the left prefrontal, the right parietal and the left occipital lobes. This is the first study to report that adiposity-related inflammation may reduce the integrity of some of the brain structures involved in reward and feeding behaviors.
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How (much) do food prices contribute to obesity in Russia?
Matthias Staudigel
Economics & Human Biology, forthcoming
Abstract:
High BMI and obesity contribute to the Russian health crisis. Previous studies have shown that weight status varies along socioeconomic lines but remains largely unaffected by economic shocks over time. This study is the first that explicitly analyses the impact of food prices on adult BMI and obesity in the Russian Federation. Using panel data from the Russia Longitudinal Monitoring Survey from 1994 to 2005, that included 10.551 urban respondents over 18 years, a reduced form weight demand function is estimated. Controlling for individual heterogeneity by a fixed-effects model, price-weight elasticities are derived. The main result is that food prices are not the essential determinants of BMI and obesity in Russia. Elasticities of BMI with respect to single food prices are low and show absolute values smaller than 0.01. However, some products like chicken meat, milk, onions and butter show significant price effects on body mass. A 20% increase in the price of chicken meat would cause a reduction in body weight of 112 g on average. In contrast to the United States, it is mainly high-income households that show significant weight reactions to food prices in Russia. Separate regressions by gender showed significant effects of milk and butter prices on male BMI and of onion prices on female BMI. The risk of being obese is even less affected by price.