More to eat
Mere experience of low subjective socioeconomic status stimulates appetite and food intake
Bobby Cheon & Ying-Yi Hong
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Among social animals, subordinate status or low social rank is associated with increased caloric intake and weight gain. This may reflect an adaptive behavioral pattern that promotes acquisition of caloric resources to compensate for low social resources that may otherwise serve as a buffer against environmental demands. Similarly, diet-related health risks like obesity and diabetes are disproportionately more prevalent among people of low socioeconomic resources. Whereas this relationship may be associated with reduced financial and material resources to support healthier lifestyles, it remains unclear whether the subjective experience of low socioeconomic status may alone be sufficient to stimulate consumption of greater calories. Here we show that the mere feeling of lower socioeconomic status relative to others stimulates appetite and food intake. Across four studies, we found that participants who were experimentally induced to feel low (vs. high or neutral) socioeconomic status subsequently exhibited greater automatic preferences for high-calorie foods (e.g., pizza, hamburgers), as well as intake of greater calories from snack and meal contexts. Moreover, these results were observed even in the absence of differences in access to financial resources. Our results demonstrate that among humans, the experience of low social class may contribute to preferences and behaviors that risk excess energy intake. These findings suggest that psychological and physiological systems regulating appetite may also be sensitive to subjective feelings of deprivation for critical nonfood resources (e.g., social standing). Importantly, efforts to mitigate the socioeconomic gradient in obesity may also need to address the psychological experience of low social status.
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Childhood Bullying Victimization and Overweight in Young Adulthood: A Cohort Study
Jessie Baldwin et al.
Psychosomatic Medicine, November/December 2016, Pages 1094-1103
Objective: To test whether bullied children have an elevated risk of being overweight in young adulthood and whether this association is: (1) consistent with a dose-response relationship, namely, its strength increases with the chronicity of victimization; (2) consistent across different measures of overweight; (3) specific to bullying and not explained by co-occurring maltreatment; (4) independent of key potential confounders; and (5) consistent with the temporal sequence of bullying preceding overweight.
Method: A representative birth cohort of 2,232 children was followed to age 18 years as part of the Environmental Risk Longitudinal Twin Study. Childhood bullying victimization was reported by mothers and children during primary school and early secondary school. At the age-18 follow-up, we assessed a categorical measure of overweight, body mass index, and waist-hip ratio. Indicators of overweight were also collected at ages 10 and 12. Co-twin body mass and birth weight were used to index genetic and fetal liability to overweight, respectively.
Results: Bullied children were more likely to be overweight than non-bullied children at age 18, and this association was (1) strongest in chronically bullied children (odds ratio = 1.69; 95% confidence interval [CI] = 1.21-2.35); (2) consistent across measures of overweight (body mass index: b = 1.12; 95% CI = 0.37-1.87; waist-hip ratio: b = 1.76; 95% CI = 0.84-2.69); (3) specific to bullying and not explained by co-occurring maltreatment; (4) independent of child socioeconomic status, food insecurity, mental health, and cognition, and pubertal development; and (5) not present at the time of bullying victimization, and independent of childhood weight and genetic and fetal liability.
Conclusion: Childhood bullying victimization predicts overweight in young adulthood.
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Vivian Veum et al.
American Journal of Clinical Nutrition, forthcoming
Design: Forty-six men (aged 30-50 y) with body mass index (in kg/m2) >29 and waist circumference >98 cm were randomly assigned to a very high-fat, low-carbohydrate (VHFLC; 73% of energy fat and 10% of energy carbohydrate) or low-fat, high-carbohydrate (LFHC; 30% of energy fat and 53% of energy carbohydrate) diet for 12 wk. The diets were equal in energy (8750 kJ/d), protein (17% of energy), and food profile, emphasizing low-processed, lower-glycemic foods. Fat mass was quantified with computed tomography imaging.
Results: Recorded intake of carbohydrate and total and saturated fat in the LFHC and VHFLC groups were 51% and 11% of energy, 29% and 71% of energy, and 12% and 34% of energy, respectively, with no difference in protein and polyunsaturated fatty acids. Mean energy intake decreased by 22% and 14% in the LFHC and VHFLC groups. The diets similarly reduced waist circumference (11-13 cm), abdominal subcutaneous fat mass (1650-1850 cm3), visceral fat mass (1350-1650 cm3), and total body weight (11-12 kg). Both groups improved dyslipidemia, with reduced circulating triglycerides, but showed differential responses in total and low-density lipoprotein cholesterol (decreased in LFHC group only), and high-density lipoprotein cholesterol (increased in VHFLC group only). The groups showed similar reductions in insulin, insulin C-peptide, glycated hemoglobin, and homeostasis model assessment of insulin resistance. Notably, improvements in circulating metabolic markers in the VHFLC group mainly were observed first after 8 wk, in contrast to more acute and gradual effects in the LFHC group.
Conclusions: Consuming energy primarily as carbohydrate or fat for 3 mo did not differentially influence visceral fat and metabolic syndrome in a low-processed, lower-glycemic dietary context. Our data do not support the idea that dietary fat per se promotes ectopic adiposity and cardiometabolic syndrome in humans.
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David Polidori et al.
Obesity, November 2016, Pages 2289-2295
Methods: A validated mathematical method was used to calculate energy intake changes during a 52-week placebo-controlled trial in 153 patients treated with canagliflozin, a sodium glucose co-transporter inhibitor that increases urinary glucose excretion, thereby resulting in weight loss without patients being directly aware of the energy deficit. The relationship between the body weight time course and the calculated energy intake changes was analyzed using principles from engineering control theory.
Results: It was discovered that weight loss leads to a proportional increase in appetite resulting in eating above baseline by ∼100 kcal/day per kilogram of lost weight - an amount more than threefold larger than the corresponding energy expenditure adaptations.
Conclusions: While energy expenditure adaptations have often been considered the main reason for slowing of weight loss and subsequent regain, feedback control of energy intake plays an even larger role and helps explain why long-term maintenance of a reduced body weight is so difficult.
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Body Weight Can Change How Your Emotions Are Perceived
Yujung Oh, Norah Hass & Seung-Lark Lim
PLoS ONE, November 2016
Abstract:
Accurately interpreting other’s emotions through facial expressions has important adaptive values for social interactions. However, due to the stereotypical social perception of overweight individuals as carefree, humorous, and light-hearted, the body weight of those with whom we interact may have a systematic influence on our emotion judgment even though it has no relevance to the expressed emotion itself. In this experimental study, we examined the role of body weight in faces on the affective perception of facial expressions. We hypothesized that the weight perceived in a face would bias the assessment of an emotional expression, with overweight faces generally more likely to be perceived as having more positive and less negative expressions than healthy weight faces. Using two-alternative forced-choice perceptual decision tasks, participants were asked to sort the emotional expressions of overweight and healthy weight facial stimuli that had been gradually morphed across six emotional intensity levels into one of two categories - “neutral vs. happy” (Experiment 1) and “neutral vs. sad” (Experiment 2). As predicted, our results demonstrated that overweight faces were more likely to be categorized as happy (i.e., lower happy decision threshold) and less likely to be categorized as sad (i.e., higher sad decision threshold) compared to healthy weight faces that had the same levels of emotional intensity. The neutral-sad decision threshold shift was negatively correlated with participant’s own fear of becoming fat, that is, those without a fear of becoming fat more strongly perceived overweight faces as sad relative to those with a higher fear. These findings demonstrate that the weight of the face systematically influences how its emotional expression is interpreted, suggesting that being overweight may make emotional expressions appear more happy and less sad than they really are.
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Economic preferences and fast food consumption in US adults: Insights from behavioral economics
Kerem Shuval et al.
Preventive Medicine, December 2016, Pages 204-210
Objective: To examine the relationship between economic time preferences and frequency of fast food and full-service restaurant consumption among U.S. adults.
Methods: Participants included 5871 U.S. adults who responded to a survey conducted in 2011 pertaining to the lifestyle behaviors of families and the social context of these behaviors. The primary independent variable was a measure of time preferences, an intertemporal choice assessing delay discounting. This was elicited via responses to preferences for an immediate dollar amount or a larger sum in 30 (30-day time horizon) or 60 days (60-day time horizon). Outcomes were the frequency of fast food and full-service restaurant consumption. Ordered logistic regression was performed to examine the relationship between time preferences and food consumption while adjusting for covariates (e.g. socio-demographics).
Results: Multivariable analysis revealed that higher future time preferences were significantly related to less frequent fast food intake for both the 30- and 60-day time horizon variables (P for linear trend < 0.05; both). Notably, participants with the highest future time preference were significantly less likely to consume fast food than those with very low future time preferences (30-day: OR = 0.74, 95%CI: 0.62-0.89; and 60-day: OR = 0.86, 95%CI: 0.74-1.00). In comparison, higher future time preferences were not significantly associated with full-service restaurant intake (30-day: p for linear trend = 0.73; 60-day: p for linear trend = 0.83).
Conclusions: Higher future time preferences were related to a lower frequency of fast food consumption. Utilizing concepts from behavioral economics (e.g. pre-commitment contracts) to facilitate more healthful eating is warranted using experimental studies.
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The Effects of the Graduated Driver Licensing Restrictions on Teenage Obesity
Qihua Qiu
Georgia State University Working Paper, October 2016
Abstract:
Little evidence exists on the association between driving and obesity among teenagers. In this paper, I estimate the effects of Graduated Driver Licensing (GDL) restrictions on obesity prevalence among adolescents aged 14 to 17 in the U.S. My findings suggest that a mandatory holding period, nighttime restriction, or passenger restriction significantly raises adolescents’ probability of being obese by 1.57, 1.04, and 0.94 percentage points respectively, corresponding to increases in obesity rate of 12.6%, 8.3%, and 7.5%. These effects are generally stronger among male or white teenagers. Overall, I estimate that nearly 24% of the rise in obesity among teenagers aged 14 to 17 in the U.S from 1999 to 2015 can be explained by less driving due to the GDL restrictions. In addition, I find that the restrictions reduce teenagers’ exercise frequency while increasing their time spent watching TV, which may help to explain the adverse effects on obesity.
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Beyond Supermarkets: Food Outlet Location Selection in Four U.S. Cities Over Time
Pasquale Rummo et al.
American Journal of Preventive Medicine, forthcoming
Methods: Neighborhood-level data from four U.S. cities (Birmingham, AL; Chicago, IL; Minneapolis, MN; Oakland, CA) from 1986, 1993, 1996, 2001, 2006, and 2011 were used with two-step econometric models to estimate longitudinal associations between neighborhood-level characteristics (z-scores) and the log-transformed count/km2 (density) of food outlets within real estate-derived neighborhoods. Associations were examined with lagged neighborhood-level sociodemographics and lagged density of food outlets, with interaction terms for neighborhood-level income. Data were analyzed in 2016.
Results: Neighborhood-level income at earlier years was negatively associated with the current density of convenience stores (β= -0.27, 95% CI= -0.16, -0.38, p<0.001). The percentage of neighborhood white population was negatively associated with fast food restaurant density in low-income neighborhoods (10th percentile of income: β= -0.17, 95% CI= -0.34, -0.002, p=0.05), and the density of smaller grocery stores across all income levels (β= -0.27, 95% CI= -0.45, -0.09, p=0.003). There was a lack of policy-relevant associations between the pre-existing food environment and the current density of food outlet types, including supermarkets.
Conclusions: Socioeconomically disadvantaged and minority populations may attract “unhealthy” food outlets over time. To support equal access to healthy food outlets, the availability of “less healthy” food outlets types may be relatively more important than the potential lack of supermarkets or full-service restaurants.
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Food insecurity as a driver of obesity in humans: The insurance hypothesis
Daniel Nettle, Clare Andrews & Melissa Bateson
Behavioral and Brain Sciences, forthcoming
Abstract:
Integrative explanations of why obesity is more prevalent in some sectors of the human population than others are lacking. Here, we outline and evaluate one candidate explanation, the insurance hypothesis (IH). The IH is rooted in adaptive evolutionary thinking: the function of storing fat is to provide a buffer against shortfall in the food supply. Thus, individuals should store more fat when they receive cues that access to food is uncertain. Applied to humans, this implies that an important proximate driver of obesity should be food insecurity rather than food abundance per se. We integrate several distinct lines of theory and evidence that bear on this hypothesis. We present a theoretical model that shows it is optimal to store more fat when food access is uncertain, and we review the experimental literature from non-human animals showing that fat reserves increase when access to food is restricted. We provide a meta-analysis of 125 epidemiological studies of the association between perceived food insecurity and high body weight in humans. There is a robust positive association, but it is restricted to adult women in high-income countries. We explore why this could be in light of the IH and our theoretical model. We conclude that whilst the IH alone cannot explain the distribution of obesity in the human population, it may represent a very important component of a pluralistic explanation. We also discuss insights it may offer into the developmental origins of obesity, dieting-induced weight gain, and Anorexia Nervosa.
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John Cullinan & John Cawley
Economics & Human Biology, February 2017, Pages 92-103
Abstract:
Childhood overweight and obesity is a major public health challenge for policymakers in many countries. As the most common supervisors of children’s activities, parents have a potentially important role to play in obesity prevention. However, a precondition for parents to improve their children’s diets, encourage them to be more physically active, or take them to see a doctor about their weight is for the parent to first recognize that their child is overweight or obese. This paper examines the extent of parental misclassification of child weight status, and its correlates, focusing on the role of parental education and the parent’s own obesity status. We find evidence that, among non-obese parents, those who are better-educated report their child’s weight status more accurately, but among obese parents, the better-educated are 45.18% more likely than parents with lower secondary education to give a false negative report of their child’s overweight/obesity; this may reflect social desirability bias.
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Social Norms Shift Preferences for Healthy and Unhealthy Foods
Emma Templeton, Michael Stanton & Jamil Zaki
PLoS ONE, November 2016
Abstract:
This research investigated whether people change their food preferences and eating behavior in response to health-based social norms. One hundred twenty participants rated a series of healthy and unhealthy food images. After each rating, participants sometimes viewed a rating that ostensibly represented the average rating of previous participants. In fact, these average ratings were manipulated to convey a particular social norm. Participants either saw average ratings that favored healthy foods, favored unhealthy foods, or did not see any average ratings. Participants then re-rated those same food images after approximately ten minutes and again three days later. After the norm manipulation, participants were given the chance to take as many M&Ms as they wanted. Participants exposed to a healthy social norm consistently reported lower preferences for unhealthy foods as compared to participants in the other two conditions. This preference difference persisted three days after the social norm manipulation. However, health-based social norm manipulations did not influence the amount of M&Ms participants took. Although health-based social norm manipulations can influence stated food preferences, in this case they did not influence subsequent eating behavior.
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Paul von Hippel & Joseph Workman
Obesity, November 2016, Pages 2296-2300
Methods: In the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11, a nationally representative complex random sample of 18,170 U.S. children was followed from the fall of kindergarten in 2010 through the spring of second grade in 2013. Children's weight and heights were measured in schools each fall and spring. A multilevel growth model was used to estimate growth in mean BMI, overweight prevalence, and obesity prevalence during each summer and each school year.
Results: From the fall of kindergarten to the spring of second grade, the prevalence of obesity increased from 8.9% to 11.5%, and the prevalence of overweight increased from 23.3% to 28.7%. All of the increase in prevalence occurred during the two summer vacations; no increase occurred during any of the three school years.
Conclusions: The risk of obesity is higher when children are out of school than when they are in school.