Just desserts

Kevin Lewis

December 17, 2013

The Ironic Effects of Weight Stigma

Brenda Major et al.
Journal of Experimental Social Psychology, March 2014, Pages 74–80

America’s war on obesity has intensified stigmatization of overweight and obese individuals. This experiment tested the prediction that exposure to weight-stigmatizing messages threatens the social identity of individuals who perceive themselves as overweight, depleting executive resources necessary for exercising self-control when presented with high calorie food. Women were randomly assigned to read a news article about stigma faced by overweight individuals in the job market or a control article. Exposure to weight-stigmatizing news articles caused self-perceived overweight women, but not women who did not perceive themselves as overweight, to consume more calories and feel less capable of controlling their eating than exposure to non-stigmatizing articles. Weight-stigmatizing articles also increased concerns about being a target of stigma among both self-perceived overweight and non-overweight women. Findings suggest that social messages targeted at combating obesity may have paradoxical and undesired effects.


Chocolate Cake: Guilt or Celebration? Associations with Healthy Eating Attitudes, Perceived Behavioural Control, Intentions and Weight-loss

Roeline Kuijer & Jessica Boyce
Appetite, forthcoming

Food and eating are often associated with ambivalent feelings: pleasure and enjoyment, but also worry and guilt. Guilt has the potential to motivate behaviour change, but may also lead to feelings of helplessness and loss of control. This study firstly examined whether a default association of either ‘guilt’ or ‘celebration’ with a prototypical forbidden food item (chocolate cake) was related to differences in attitudes, perceived behavioural control, and intentions in relation to healthy eating, and secondly whether the default association was related to weight change over an 18 month period (and short term weight-loss in a subsample of participants with a weight-loss goal). This study did not find any evidence for adaptive or motivational properties of guilt. Participants associating chocolate cake with guilt did not report more positive attitudes or stronger intentions to eat healthy than did those associating chocolate cake with celebration. Instead, they reported lower levels of perceived behavioural control over eating and were less successful at maintaining their weight over an 18 month period. Participants with a weight-loss goal who associated chocolate cake with guilt were less successful at losing weight over a 3 month period compared to those associating chocolate cake with celebration.


Overweight Adolescents and Life Events in Childhood

Julie Lumeng et al.
Pediatrics, December 2013, Pages e1506-e1512

Objectives: To test the association of life events in childhood with overweight risk in adolescence; to examine the effects of chronicity, timing, intensity, valence, and type of life events; and to test potential moderators.

Methods: Mothers of children enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Study of Early Child Care and Youth Development responded to the Life Experiences Survey at ages 4, 9, and 11 years. Using logistic regression analysis, we tested the association of experiencing many negative life events with being overweight at age 15 years, controlling for child gender, race/ethnicity, maternal education, and maternal obesity. Child gender, maternal education, maternal obesity, child’s ability to delay gratification for food, and maternal sensitivity were tested as moderators.

Results: Among the 848 study children (82% non-Hispanic white), experiencing many negative life events was associated with a higher risk of overweight (odds ratio: 1.47 [95% confidence interval: 1.04–2.10]). Greater chronicity and negative valence of the event were associated with greater overweight risk; timing of exposure and maternal reported impact of the event were not. The association was more robust for events related to family physical or mental health and among children of obese mothers and children who waited longer for food.

Conclusions: Children who experience many negative life events are at higher risk of being overweight by age 15 years. Future work should investigate mechanisms involved in this association, particularly those connected to appetitive drive and self-regulation; these mechanisms may hold promise for obesity prevention strategies.


Perceived weight in youths and risk of overweight or obesity six years later

Hao Duong & Robert Roberts
Journal of Psychosomatic Research, forthcoming

Objective: To examine the association between perceived overweight in adolescents and the development of overweight or obesity later in life.

Methods: This paper uses data from a prospective, two-wave cohort study. Participants are 2445 adolescents 11–17 years of age who reported perceived weight at baseline and also had height and weight measured at baseline and at follow-up six years later sampled from managed care groups in a large metropolitan area.

Results: Youths who perceived themselves as overweight at baseline were approximately 2.5 times as likely to be overweight or obese six years later compared to youths who perceived themselves as average weight (OR = 2.45, 95% CI = 1.77-3.39), after adjusting for weight status at baseline, demographic characteristics, major depression, physical activity and dieting behaviors. Those who perceived themselves as skinny were less likely to be overweight or obese later (OR = 0.36, 95% CI = 0.27-0.49).

Conclusions: Perceived overweight was associated with overweight or obesity later in life. This relationship was not fully explained by extreme weight control behaviors or major depression. Further research is needed to explore the mechanism involved.


Humans are not fooled by size illusions in attractiveness judgements

Melissa Bateson et al.
Evolution and Human Behavior, forthcoming

Could signallers use size contrast illusions to dishonestly exaggerate their attractiveness to potential mates? Using composite photographs of women from three body mass index (BMI) categories designed to simulate small groups, we show that target women of medium size are judged as thinner when surrounded by larger women than when surrounded by thinner women. However, attractiveness judgements of the same target women were unaffected by this illusory change in BMI, despite small true differences in the BMIs of the target women themselves producing strong effects on attractiveness. Thus, in the context of mate choice decisions, the honesty of female body size as a signal of mate quality appears to have been maintained by the evolution of assessment strategies that are immune to size contrast illusions. Our results suggest that receiver psychology is more flexible than previously assumed, and that illusions are unlikely to drive the evolution of exploitative neighbour choice in human sexual displays.


A brisk walk, compared with being sedentary, reduces attentional bias and chocolate cravings among regular chocolate eaters with different body mass

Hwajung Oh & Adrian Taylor
Appetite, December 2013, Pages 144–149

Poor self-regulation of high energy snacking has been linked to weight gain. Physical activity can acutely reduce chocolate consumption and cravings but the effects on attentional bias (AB) are unknown. The study aimed to test the effects of exercise among normal and overweight/obese individuals during temporary and longer abstinence. Participants were 20 normal and 21 overweight regular female chocolate eaters (after 24 h abstinence), and 17 females (after ⩾1 week abstinence during Lent). They were randomly assigned to engage in 15 min brisk walking or rest, on separate days. AB was assessed using an adapted dot probe task pre and post-treatment at each session, with chocolate/neutral paired images presented for 200 ms (initial AB; IAB) or 1000 ms (maintained AB; MAB). Chocolate craving was assessed pre, during, immediately after, and 5 min and 10 min after treatment, using a 0–100 visual analogue score. Three-way mixed ANOVAs revealed that there was no significant interaction effect between group (i.e., BMI status, or abstinence status) and condition × time for craving and AB to chocolate cues. Fully repeated 2-way ANOVAS revealed a significant condition × time interaction for IAB (F(1, 57) = 6.39) and chocolate craving (F(2.34, 133.19) = 14.44). After exercise IAB (t(57) = 2.78, p < 0.01) was significantly lower than after the rest condition. Craving was significantly lower than the rest condition at all assessments post-baseline. A short bout of physical activity reduces cravings and AB to chocolate cues, relative to control, irrespective of BMI or abstinence period.


Personality Traits, Education, Physical Exercise, and Childhood Neurological Function as Independent Predictors of Adult Obesity

Helen Cheng & Adrian Furnham
PLoS ONE, November 2013

Objective: To investigate whether personality traits, education, physical exercise, parental socio-economic conditions, and childhood neurological function are independently associated with obesity in 50 year old adults in a longitudinal birth cohort study.

Method: The sample consisted of 5,921 participants born in Great Britain in 1958 and followed up at 7, 11, 33, 42, and 50 years with data on body mass index measured at 42 and 50 years.

Results: There was an increase of adult obesity from 14.2% at age 42 to 23.6% at 50 years. Cohort members who were reported by teachers on overall clumsiness as “certainly applied” at age 7 were more likely to become obese at age 50. In addition, educational qualifications, traits Conscientiousness and Extraversion, psychological distress, and physical exercise were all significantly associated with adult obesity. The associations remained to be significant after controlling for birth weight and gestation, maternal and paternal BMI, childhood BMI, childhood intelligence and behavioural adjustment, as well as diet.

Conclusion: Neurological function in childhood, education, trait Conscientiousness, and exercise were all significantly and independently associated with adult obesity, each explained unique individual variability.


Acute Effect of Oatmeal on Subjective Measures of Appetite and Satiety Compared to a Ready-to-Eat Breakfast Cereal: A Randomized Crossover Trial

Candida Rebello et al.
Journal of the American College of Nutrition, July/August 2013, Pages 272-279

Objective: The physicochemical properties of soluble oat fiber (β-glucan) affect viscosity-dependent mechanisms that influence satiety. The objective of this study was to compare the satiety impact of oatmeal with the most widely sold ready-to-eat breakfast cereal (RTEC) when either was consumed as a breakfast meal.

Methods: Forty-eight healthy individuals ≥18 years of age were enrolled in a randomized crossover trial. Following an overnight fast, subjects consumed either oatmeal or RTEC in random order at least a week apart. The breakfasts were isocaloric and contained 363 kcal (250 kcal cereal, 113 kcal milk). Visual analogue scales measuring appetite and satiety were completed before breakfast and throughout the morning. The content and physicochemical properties of oat β-glucan were determined. Appetite and satiety responses were analyzed by area under the curve (AUC). Physicochemical properties were analyzed using t tests.

Results: Oatmeal, higher in fiber and protein but lower in sugar than the RTEC, resulted in greater increase in fullness (AUC: p = 0.005 [120 minute: p = 0.0408, 180 minute: p = 0.0061, 240 minute: p = 0.0102]) and greater reduction in hunger (AUC: p = 0.0009 [120 minute: p = 0.0197, 180 minute: p = 0.0003, 240 minute: p = 0.0036]), desire to eat (AUC: p = 0.0002 [120 minute: p = 0.0168, 180 minute: p < 0.0001, 240 minute: p = 0.0022]), and prospective intake (AUC: p = 0.0012 [120 minute: p = 0.0058, 180 minute: p = 0.006, 240 minute: p = 0.0047]) compared to the RTEC. Oatmeal had higher β-glucan content, higher molecular weight (p < 0.0001), higher viscosity (p = 0.025), and larger hydration spheres (p = 0.0012) than the RTEC.

Conclusion: Oatmeal improves appetite control and increases satiety. The effects may be attributed to the viscosity and hydration properties of its β-glucan content.


Calories and portion sizes in recipes throughout 100 years: An overlooked factor in the development of overweight and obesity?

Maj Bloch Eidner et al.
Scandinavian Journal of Public Health, December 2013, Pages 839-845

Background: Large portion sizes have been associated with large energy intake, which can contribute to the development of overweight and obesity. Portion sizes of non-home cooked food have increased in the past 20 years, however, less is known about portion sizes of home-cooked food.

Aim: The aim of the study was to assess if the portion sizes measured in calories in Danish cookbook recipes have changed throughout the past 100 years.

Methods: Portion size measured in calories was determined by content-analysis of 21 classic Danish recipes in 13 editions of the famous Danish cookbook “Food” from 1909 to 2009. Calorie content of the recipes was determined in standard nutritional software, and the changes in calories were examined by simple linear regression analyses.

Results: Mean portion size in calories increased significantly by 21% (β = 0.63; p < 0.01) over the past 100 years in the analyzed recipes. The mean portion size in calories from a composed homemade meal increased by 77% (β = 2.88; p < 0.01). The mean portion size in calories from meat increased by 27% (β = 0.85; p = 0.03), starchy products increased by 148% (β = 1.28; p < 0.01), vegetables increased by 37% (β = 0.21; p = 0.13) and sauce increased by 47% (β = 0.56; p = 0.02) throughout the years.

Conclusions: Portion sizes measured in calories in classical Danish recipes have increased significantly in the past 100 years and can be an important factor in increased energy intake and the risk of developing overweight and obesity.


Maternal Work and Children's Diet, Activity, and Obesity

Ashlesha Datar, Nancy Nicosia & Victoria Shier
University of Southern California Working Paper, November 2013

Mothers’ work hours are likely to affect their time allocation towards activities related to children’s diet, activity and well-being. For example, mothers who work more may be more reliant on processed foods, foods prepared away from home and school meal programs for their children’s meals. A greater number of work hours may also lead to more unsupervised time for children that may, in turn, allow for an increase in unhealthy behaviors among their children such as snacking and sedentary activities such as TV watching. Using data on a national cohort of children, we examine the relationship between mothers’ average weekly work hours during their children’s school years on children’s dietary and activity behaviors, BMI and obesity in 5th and 8th grade. Our results are consistent with findings from the literature that maternal work hours are positively associated with children’s BMI and obesity especially among children with higher socioeconomic status. Unlike previous papers, our detailed data on children’s behaviors allow us to speak directly to affected behaviors that may contribute to the increased BMI. We show that children whose mothers work more consume more unhealthy foods (e.g. soda, fast food) and less healthy foods (e.g. fruits, vegetables, milk) and watch more television. Although they report being slightly more physically active, likely due to organized physical activities, the BMI and obesity results suggest that the deterioration in diet and increase in sedentary behaviors dominate.


Racial Differences in the Influence of Female Adolescents’ Body Size on Dating and Sex

Mir Ali et al.
Economics & Human Biology, forthcoming

This paper investigates the effect of body size on dating and sexual experiences of white (non-Hispanic) and African American (non-Hispanic) female adolescents. Using data from Add-Health, we estimate the effects of obesity and BMI z-score on the probability of having been involved in a romantic relationship, having ever been touched in the genital area in a sexual way, and having ever engaged in sexual intercourse. We find that obese white teenage girls are less likely to have been in a romantic relationship compared to their non-obese counterparts. In addition, obese white girls are less likely to ever have had sex (intercourse) or to ever have been intimate. There are no systematic differences in relationship experiences and sexual behaviors between obese and non-obese black girls. Overall, the estimated relationships are very robust to common environmental influences at the school-level and to the inclusion of proxies for low self-esteem, attitudes towards sex and interviewer assessment of appearance and personality. Instrumental variables estimates and estimates from models with lagged weight status confirm the overall patterns.


Change in BMI Accurately Predicted by Social Exposure to Acquaintances

Rahman Oloritun et al.
PLoS ONE, November 2013

Research has mostly focused on obesity and not on processes of BMI change more generally, although these may be key factors that lead to obesity. Studies have suggested that obesity is affected by social ties. However these studies used survey based data collection techniques that may be biased toward select only close friends and relatives. In this study, mobile phone sensing techniques were used to routinely capture social interaction data in an undergraduate dorm. By automating the capture of social interaction data, the limitations of self-reported social exposure data are avoided. This study attempts to understand and develop a model that best describes the change in BMI using social interaction data. We evaluated a cohort of 42 college students in a co-located university dorm, automatically captured via mobile phones and survey based health-related information. We determined the most predictive variables for change in BMI using the least absolute shrinkage and selection operator (LASSO) method. The selected variables, with gender, healthy diet category, and ability to manage stress, were used to build multiple linear regression models that estimate the effect of exposure and individual factors on change in BMI. We identified the best model using Akaike Information Criterion (AIC) and R2. This study found a model that explains 68% (p<0.0001) of the variation in change in BMI. The model combined social interaction data, especially from acquaintances, and personal health-related information to explain change in BMI. This is the first study taking into account both interactions with different levels of social interaction and personal health-related information. Social interactions with acquaintances accounted for more than half the variation in change in BMI. This suggests the importance of not only individual health information but also the significance of social interactions with people we are exposed to, even people we may not consider as close friends.


Saturated fat consumption may not be the main cause of increased blood lipid levels

C.B. Dias et al.
Medical Hypotheses, forthcoming

Consumption of foods rich in saturated fatty acids (SFA) has often been associated with elevated blood lipid levels and consequently with risk for chronic diseases, including coronary heart disease. However, epidemiological and interventional studies on this topic are contradictory. While some studies have established a positive link, other studies have failed to show a significant association between saturated fat consumption and blood lipid levels, and others have even found an inverse association. Moreover, studies using animal models have demonstrated that dietary saturated fats raise blood lipid (cholesterol and triglycerides) levels only when the diet is deficient in omega-3 polyunsaturated fatty acids (n-3PUFA). The n-3PUFA are known for their potential in the management of hyperlipidaemia for the prevention of coronary heart disease, as well as for their anti-arrhythmic, anti-aggregatory and anti-inflammatory potential. We believe that with an adequate consumption of n-3PUFA dietary saturated fat may not result in elevated blood lipid levels. Therefore, we critically evaluated the literature regarding saturated fat and blood lipid level, with an emphasis on the role of n-3PUFA on this relationship. Evidence from animal studies and few clinical trials lead to the hypothesis that there are beneficial or neutral effects of saturated fatty acids when combined with recommended levels of n-3PUFA in the diet. However, an intervention focusing on the background fat when the volunteers’ diet is supplemented with n-3PUFA is yet to be done. Proving the authenticity of this hypothesis would mean a substantial change in public health messages regarding saturated fats and their health effects; and also a change in the strategies related to prevention of chronic cardiac and artery diseases.


Density and Proximity of Fast Food Restaurants and Body Mass Index Among African Americans

Lorraine Reitzel et al.
American Journal of Public Health, January 2014, Pages 110-116

Objectives: The purpose of this study was to address current gaps in the literature by examining the associations of fast food restaurant (FFR) density around the home and FFR proximity to the home, respectively, with body mass index (BMI) among a large sample of African American adults from Houston, Texas.

Methods: We used generalized linear models with generalized estimating equations to examine associations of FFR density at 0.5-, 1-, 2-, and 5-mile road network buffers around the home with BMI and associations of the closest FFR to the home with BMI. All models were adjusted for a range of individual-level covariates and neighborhood socioeconomic status. We additionally investigated the moderating effects of household income on these relations. Data were collected from December 2008 to July 2009.

Results: FFR density was not associated with BMI in the main analyses. However, FFR density at 0.5, 1, and 2 miles was positively associated with BMI among participants with lower incomes (P ≤ .025). Closer FFR proximity was associated with higher BMI among all participants (P < .001), with stronger associations emerging among those of lower income (P < .013) relative to higher income (P < .014).

Conclusions: Additional research with more diverse African American samples is needed, but results supported the potential for the fast food environment to affect BMI among African Americans, particularly among those of lower economic means.


Genetic Analysis of Low BMI Phenotype in the Utah Population Database

William Yates et al.
PLoS ONE, December 2013

The low body mass index (BMI) phenotype of less than 18.5 has been linked to medical and psychological morbidity as well as increased mortality risk. Although genetic factors have been shown to influence BMI across the entire BMI, the contribution of genetic factors to the low BMI phenotype is unclear. We hypothesized genetic factors would contribute to risk of a low BMI phenotype. To test this hypothesis, we conducted a genealogy data analysis using height and weight measurements from driver's license data from the Utah Population Data Base. The Genealogical Index of Familiality (GIF) test and relative risk in relatives were used to examine evidence for excess relatedness among individuals with the low BMI phenotype. The overall GIF test for excess relatedness in the low BMI phenotype showed a significant excess over expected (GIF 4.47 for all cases versus 4.10 for controls, overall empirical p-value<0.001). The significant excess relatedness was still observed when close relationships were ignored, supporting a specific genetic contribution rather than only a family environmental effect. This study supports a specific genetic contribution in the risk for the low BMI phenotype. Better understanding of the genetic contribution to low BMI holds promise for weight regulation and potentially for novel strategies in the treatment of leanness and obesity.


Does Walkability Influence Housing Prices?

Austin Boyle, Charles Barrilleaux & Daniel Scheller
Social Science Quarterly, forthcoming

Objective: We examine the effects of neighborhood walkability on house values. Recent research claims that walkability makes homes more valuable, ceteris paribus. We contend that some studies report a spurious effect of walkability because of differences between areas with high and low walkability.

Methods: We replicate the positive effect of walkability on prices for single-family homes and condominiums in Miami, Florida, using a unique data set of house values and characteristics. We employ a fixed effects regression model instead of a traditional ordinary least squares regression model to account for the unobserved heterogeneity of neighborhoods.

Results: We find that walkability's impact on housing value becomes statistically insignificant at the margin after controlling for heteroscedasticity and neighborhood fixed effects.

Conclusions: The significant impact of the fixed effects suggests that something other than walkability is affecting prices and that better specified models are needed to discern the real price effects of walkability.


Extraverted Children Are More Biased by Bowl Sizes than Introverts

Koert van Ittersum & Brian Wansink
PLoS ONE, October 2013

Extraverted children are hypothesized to be most at risk for over-serving and overeating due to environmental cues – such as the size of dinnerware. A within-subject field study of elementary school students found that extraverted children served themselves 33.1% more cereal in larger bowls (16-oz) than in smaller (12-oz) bowls, whereas introverted children were unaffected by bowl size (+5.6%, ns). However, when children were asked by adults how much cereal they wanted to eat, both extraverted and introverted children requested more cereal when given a large versus small bowl. Insofar as extraverted children appear to be more biased by environmental cues, this pilot study suggests different serving styles are recommended for parents and other caregivers. They should serve extraverts, but allow introverts to serve themselves. Still, since the average child still served 23.2% more when serving themselves than when served by an adult, it might be best for caregivers to do the serving whenever possible – especially for extraverted children.

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