Weighty Issues

Kevin Lewis

October 26, 2009

Obesity and Price Sensitivity at the Supermarket

Neil Gandal & Anastasia Shabelansky
Tel Aviv University Working Paper, September 2009

In this paper, we employ a rich data set at the individual level in order to examine which factors are most highly correlated with obesity. Our main result is that, even after controlling for income levels and other factors, we find that high 'price-sensitivity' for food products is associated with high obesity rates. We find that a woman who stated that prices were 'not important at all' when purchasing food products had a Body Mass Index (BMI) that was 1.3 units below those who stated that price was 'very important.' This suggests that the price effect is not trivial and obesity is a problem that is not limited to those with low income levels. A 1.3 unit reduction in the BMI would move approximately 28% of women who are in the 'overweight' category to the 'normal weight' category and 25% of women who are in the 'obese' category to the 'overweight' category.


Physician Respect for Patients with Obesity

Mary Margaret Huizinga, Lisa Cooper, Sara Bleich, Jeanne Clark & Mary Catherine Beach
Journal of General Internal Medicine, forthcoming

Introduction: Obesity stigma is common in our society, and a general stigma towards obesity has also been documented in physicians. We hypothesized that physician respect for patients would be lower in patients with higher body mass index (BMI).

Methods: We analyzed data from the baseline visit of 40 physicians and 238 patients enrolled in a randomized controlled trial of patient-physician communication. The independent variable was BMI, and the outcome was physician respect for the patient. We performed Poisson regression analyses with robust variance estimates, accounting for clustering of patients within physicians, to examine the association between BMI and physician ratings of respect for particular patients.

Results: The mean (SD) BMI of the patients was 32.9(8.1) kg/m2. Physicians had low respect for 39% of the participants. Higher BMI was significantly and negatively associated with respect [prevalence ratio (PrR) 0.83, 95% CI: 0.73-0.95; p = 0.006; per 10 kg/m2 increase in BMI]. BMI remained significantly associated with respect after adjustment for patient age and gender (PrR 0.86, 95%CI: 0.74-1.00; p = 0.049).

Conclusion: We found that higher patient BMI was associated with lower physician respect. Further research is needed to understand if lower physician respect for patients with higher BMI adversely affects the quality of care.


Height and Body Mass Index Values of Nineteenth Century New York Legislators

Howard Bodenhorn
Economics & Human Biology, forthcoming

Previous studies of mid-nineteenth century American BMI values have used data created by military academies and penitentiaries. This paper uses an alternative data set, constructed from legislative documents in which the heights and weights of New York State legislators were recorded. The results reveal that middle to upper-middle class Americans maintained BMI values closer to the modern standard than did students and prisoners. The average BMI value among this group was 24 and their height-weight combinations did not greatly diverge from historical mortality risk optima.


Life and death during the Great Depression

José Tapia Granados & Ana Diez Roux
Proceedings of the National Academy of Sciences, forthcoming

Recent events highlight the importance of examining the impact of economic downturns on population health. The Great Depression of the 1930s was the most important economic downturn in the U.S. in the twentieth century. We used historical life expectancy and mortality data to examine associations of economic growth with population health for the period 1920-1940. We conducted descriptive analyses of trends and examined associations between annual changes in health indicators and annual changes in economic activity using correlations and regression models. Population health did not decline and indeed generally improved during the 4 years of the Great Depression, 1930-1933, with mortality decreasing for almost all ages, and life expectancy increasing by several years in males, females, whites, and nonwhites. For most age groups, mortality tended to peak during years of strong economic expansion (such as 1923, 1926, 1929, and 1936-1937). In contrast, the recessions of 1921, 1930-1933, and 1938 coincided with declines in mortality and gains in life expectancy. The only exception was suicide mortality which increased during the Great Depression, but accounted for less than 2% of deaths. Correlation and regression analyses confirmed a significant negative effect of economic expansions on health gains. The evolution of population health during the years 1920-1940 confirms the counterintuitive hypothesis that, as in other historical periods and market economies, population health tends to evolve better during recessions than in expansions.


Early trauma and adult obesity: Is psychological dysfunction the mediating mechanism?

Alberto D'Argenio, Cristina Mazzi, Luca Pecchioli, Giorgio Di Lorenzo, Alberto Siracusano & Alfonso Troisi
Physiology & Behavior, forthcoming

Several studies have shown that physical and/or sexual abuse during childhood may lead to the development of obesity later in life. Despite these consistent findings, the mechanism for the increased risk of obesity following developmental trauma is unknown. It has been suggested that psychological dysfunction, including the presence of disordered eating behavior, may account for the added risk of adult obesity. To test this hypothesis, we analyzed the prevalence and severity of different types of early traumatic life events, assessed the presence of co-existing psychiatric disorders and measured adult attachment style in a sample of 200 subjects including non-obese healthy volunteers and obese participants undergoing a psychiatric assessment to determine suitability for bariatric surgery. Participants who scored higher on a scale measuring the severity of traumatic events experienced during the first 15 years of their lives were more likely to be obese at the time of testing. The exclusion of the participants who experienced physical and/or sexual abuse did not change the results of statistical analysis. Severity of early trauma remained a significant predictor of adult obesity when the influence of psychiatric diagnosis and anxious attachment was taken into account. These findings suggest that: (1) not only sexual or physical abuse but also less severe forms of early-life stress are linked to the development of obesity later in life; and (2) psychological dysfunction is not the only mechanism mediating the elevated risk of obesity in persons exposed to early life trauma.


Evolution of obesity by social status in France, 1981-2003

Thibaut de Saint Pol
Economics & Human Biology, December 2009, Pages 398-404

Although France is less affected by the rise in obesity than neighboring countries, the prevalence of obesity has increased, changing the distribution of this pathology in the population. We analyze this evolution by social status, education, income and gender, region of residence, using the three French national Health Surveys conducted in 1981, 1992 and 2003. The average body weight of both women and men has increased in France since 1981 and accelerated since the 1990s. This trend is obtained among all age groups. Nevertheless, this process did not affect all socioeconomic groups similarly. Geographical differences increased between north-east, where the prevalence of obesity is higher, and the Mediterranean region, where it is lower. Likewise, the gap between social and occupational categories has greatly widened: obesity has increased much faster among farmers and blue-collar workers than among managers and professionals. In contrast to women, poorer men are not more likely to be more obese than others. Our findings suggest that differences in BMI values increased substantially among social groups in France, in particular among women.


Economics of Food Energy Density and Adolescent Body Weight

Christopher Auld & Lisa Powell
Economica, October 2009, Pages 719-740

We present a simple microeconomic behavioral model showing that decreases in the price of energy-dense foods increase body weight if the price of obtaining a calorie from dense food is lower than that of less dense food. Estimates of the determinants of adolescent BMI suggest that the price of high-density food is negatively related to BMI whereas the price of low density food is positively related. Restaurant availability is not associated with weight, but increases in supermarket density predict lower weight. Quantile regressions show that most of the changes in body weight occur in the top quintile of the conditional distribution of BMI.


Unsure What the Future Will Bring? You May Overindulge: Uncertainty Increases the Appeal of Wants over Shoulds

Katherine Milkman
University of Pennsylvania Working Paper, April 2009

This paper examines the effect of uncertainty about the future on whether individuals select want options (e.g., junk foods, lowbrow films) or should options (e.g., healthy foods, highbrow films). As predicted by the dual systems theory of want/should conflict, uncertainty about what the future may bring increases individuals' tendency to favor want options over should options, and these results hold even when individuals are able to make choices contingent upon the outcomes of uncertain events. These results are strongest in situations where uncertainty pertains to similar outcomes, suggesting that the effects of uncertainty are enhanced when a decision maker finds it more difficult to distinguish between the possible contingencies she faces. Overall, this work suggests that reducing uncertainty in a decision maker's environment may have a "halo effect", leading to less impulsive choices. Implications for theories of want/should conflict, managers, policy makers, and individuals are discussed.


Caught in the Bulimic Trap? Socioeconomic Status, State Dependence, and Unobserved Heterogeneity

Michelle Sovinsky Goeree, John Ham & Daniela Iorio
University of Southern California Working Paper, September 2009

Eating disorders are an important and growing health concern, and bulimia nervosa (BN) accounts for the largest fraction of eating disorders (ED). Health consequences of BN are substantial and especially serious given the increasingly compulsive nature of the disorder. However, remarkably little is known about the mechanisms underlying the persistent nature of BN and the socioeconomic groups that are most likely to be at risk. Using a unique panel data set on young women and instrumental variable techniques, we document that unobserved heterogeneity plays a role in the persistence of BN, but strikingly up to two thirds is due to true state dependence. Our results, together with support from the medical literature, provide strong evidence that bulimia should be considered an addiction. We also find that African Americans are more likely to exhibit and persist in bulimic behavior than Whites; as are girls from low income families compared to middle and high income families. These results stand in stark contrast to the popular conceptions of who is most likely to experience an ED, and we argue that an important cause of this is differences in diagnosis across racial and income classes. Our findings have important implications for public policy since they i) provide direction to policy makers regarding which adolescent females are most at risk for BN, and ii) suggest that the timing of the policy is crucial: preventive educational programs should be coupled with more intense (rehabilitation) treatment at the early stages of bingeing and purging behaviors. Our results are robust to different model specifications and identifying assumptions.


Percent Body Fat is Related to Delay and Probability Discounting for Food in Humans

Erin Rasmussen & Steven Lawyer
Behavioural Processes, forthcoming

This study describes delay and probability discounting patterns for hypothetical food and money in relation to percent body fat (PBF). Sixty university students completed four computerized discounting tasks in which they were asked to make a series of hypothetical decisions between a) 10 dollars after 1 of several different delays (1, 2, 30, 180, and 365 days) or a smaller amount of money available immediately; b) 10 bites of food after one of several delays (1, 2, 5, 10, and 20 hours) or a smaller number of bites available immediately; c) $10 at one of several probabilities (0.9, 0.75, 0.5, 0.25, 0.1) or a smaller amount of money to be received for sure; and d) 10 bites of food at one of several probabilities (0.9, 0.75, 0.5, 0.25, 0.1) or a smaller number of bites to be received for sure. Median indifference points for all participants across each task were well described using the hyperbolic discounting function. Results suggest that percent body fat (PBF) predicted discounting for hypothetical food, but not money, using regression analyses with the entire sample and when comparing individuals in the high and low quartiles for PBF. None of the other dietary variables (body mass index, subjective hunger, and time since last meal or snack) were related to discounting patterns. This suggests that individuals with high PBF may exhibit heightened sensitivities to delay and probability when making decisions about food.


Convergence of obesity and high glycemic diet on compounding diabetes and cardiovascular risks in modernizing China: An emerging public health dilemma

Eric Ding & Vasanti Malik
Globalization and Health, February 2008

As China is undergoing dramatic development, it is also experiencing major societal changes, including an emerging obesity epidemic, with the prevalence of overweight and obesity doubling in the past decade. However, the implications of a high glycemic index (GI) and glycemic load (GL) traditional Chinese diet are adversely changing in modern times, as a high-glycemic diet is becoming a greater contributor to diabetes and cardiovascular risks in a population with rising obesity and decreasing physical activity. Specifically, a high GI diet adversely impacts metabolism and appetite control regulation, and notably confers substantially greater risk of weight gain, type 2 diabetes, cardiovascular disease, and certain cancers among overweight and obese individuals (P<0.05 for all); leading to an emerging vicious cycle of compounding adverse health risks. Notably, while no elevated risk of cardiovascular disease and type 2 diabetes were observed with higher GL intake among normal weight individuals, among overweight individuals, higher GL was strongly associated with higher risk of coronary heart disease (RR=2.00, 95%CI: 1.31-2.96), stroke (RR=2.13, 1.28-3.53), and type 2 diabetes (RR=1.52, 1.22-1.89 among Chinese). Additionally, the influx of Western-diets rich in saturated fats and high-glycemic sugar-sweetened beverages also threaten the health of the population. This review highlights the emerging adverse convergence of a high-glycemic Asian diet with a Chinese society experiencing an emerging obesity epidemic, and the important implications of these combined factors on compounding cardiometabolic risks. Potential policy directions in China are also discussed.

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