The Long-term Value of Bariatric Surgery Interventions for American Adults With Type 2 Diabetes Mellitus.

BACKGROUND: Bariatric surgery can cause type 2 diabetes (diabetes) remission for individuals with comorbid obesity, yet utilization is <1%. Surgery eligibility is currently limited to body mass index (BMI) ≥35 kg/m 2 , though the American Diabetes Association recommends expansion to BMI ≥30 kg/m 2 . OBJECTIVE: We estimate the individual-level net social value benefits of diabetes remission through bariatric surgery and compare the population-level effects of expanding eligibility alone versus improving utilization for currently eligible individuals. METHODS: Using microsimulation, we quantified the net social value (difference in lifetime health/economic benefits and costs) of bariatric surgery-related diabetes remission for Americans with obesity and diabetes. We compared projected lifetime surgical outcomes to conventional management at individual and population levels for current utilization (1%) and eligibility (BMI ≥35 kg/m 2 ) and expansions of both (>1%, and BMI ≥30 kg/m 2 ). RESULTS: The per capita net social value of bariatric surgery-related diabetes remission was $264,670 (95% confidence interval: $234,527-294,814) under current and $227,114 (95% confidence interval: $205,300-248,928) under expanded eligibility, an 11.1% and 9.16% improvement over conventional management. Quality-adjusted life expectancy represented the largest gains (current: $194,706; expanded: $169,002); followed by earnings ($51,395 and $46,466), and medical savings ($41,769 and $34,866) balanced against the surgery cost ($23,200). Doubling surgical utilization for currently eligible patients provides higher population gains ($34.9B) than only expanding eligibility at current utilization ($29.0B). CONCLUSIONS: Diabetes remission following bariatric surgery improves healthy life expectancy and provides net social benefit despite high procedural costs. Per capita benefits appear greater among currently eligible individuals. Therefore, policies that increase utilization may produce larger societal value than expanding eligibility criteria alone.

Improving Diet Quality in U.S. Adults: A 30-Year Health and Economic Impact Microsimulation.

INTRODUCTION: Epidemiologic studies relating health outcomes to dietary patterns captured by diet quality indices have shown better quality scores associated with lower mortality and chronic disease incidence. However, changing chronic disease risk factors only alters population health over time, and initial diet quality systematically varies across the population by sociodemographic status. This study uses microsimulation to examine 30-year impacts of improved diet quality by sociodemographic group. METHODS: Diet quality across 12 sex-, race/ethnicity-, and education-defined subgroups was estimated from the 2011-2012 National Health and Nutrition Examination Survey. In 2021, the Future Adults (dynamic microsimulation) Model was used to simulate population health and economic outcomes over 30 years for these subgroups and all adults. The modeled pathway was through lowering risk for heart disease by following U.S. Dietary Guidelines. RESULTS: Diet quality varied across the sociodemographic subgroups, and half of U.S. adults had diet quality that would be classified as poor. Improving U.S. diet quality to that reported for the top 20% in 2 large health professionals' samples could reduce incidence of heart disease by 9.9% (7.6%-13.8% across the 12 sociodemographic groups) after 30 years. Year 30 would also have 37,000 fewer deaths, 694,000 more quality-adjusted life years, and healthcare cost savings of $59.6 billion (2019 U.S. dollars). CONCLUSIONS: Dynamic microsimulation enables predictions of socially important outcomes of prevention efforts, most of which are many years in the future and beyond the scope of trials. This paper estimates the 30-year population health and economic impact of poor diet quality by sociodemographic group.

Depressive Symptoms among US Adults during the Great Recession and Economic Recovery.

BACKGROUND AND AIMS: We study the trajectory of depressive symptoms among US adults before, during, and after the 2008/2009 Great Recession. METHODS: We use repeated cross-sectional surveys of the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2018. Mental health is assessed with the Patient Health Questionnaire-9 (PHQ-9), with the following categorization for depressive symptoms: none or mild (score 0-9), moderate or severe (score 10-27). A parallel time series was calculated from the Behavioral Risk Factor Surveillance System (BRFSS) on self-reported number of days with poor mental health. RESULTS: NHANES data show a statistically significant increase in depressive symptoms from 2005/2006 to 2007/2008 (the beginning of the Great Recession), but there were no significant or consistent changes after 2007/2008. In particular, the deterioration in the adjusted predicted PHQ-9 scores occurred prior to the large increase in unemployment rate (2009/2010). As the macroeconomic situations improved and unemployment rates recovered, mental health did not return to the previous level. In the latest wave of NHANES (2017/2018), unemployment rates were at the lowest level over the analysis period; however, the adjusted predicted PHQ-9 scores were higher than that at the beginning of the Great Recession. Trends of PHQ-9 scores were similar across income groups - all groups had an increase in depressive symptoms after 2005/2006 and PHQ-9 scores were still high in 2017/2018 after controlling for sociodemographic status. Group with the lowest income had higher levels of depressive symptoms at every time point. BRFSS data shows no consistent changes in the number of days with poor mental health that parallel economic conditions. DISCUSSION: Depressive symptoms at the population level did not match the economic cycle before, during and after the Great Recession. Future research is needed to better understand the lack of correlation between population mental health and macroeconomic conditions.

Microsimulation projections of obesity interventions on cardiometabolic health disparities in the United States.

OBJECTIVE: The aim of this study was to estimate long-term impacts of health education interventions on cardiometabolic health disparities. METHODS: The model simulates how health education implemented in the United States throughout 2019 to 2049 would lead to changes in adult BMI and consequent hypertension and type 2 diabetes. Health outcome changes by sex, racial/ethnic (non-Hispanic White, non-Hispanic Black, and Hispanic), and weight status (normal: 18.5 ≤ BMI < 25; overweight: 25 ≤ BMI < 30; and obesity: 30 ≤ BMI) subpopulations were compared under a scenario with and one without health education. RESULTS: By 2049, the intervention would reduce average BMI of women with obesity to 27.7 kg/m2 (CI: 27.4-27.9), which would be 2.9 kg/m2 lower than the expected average BMI without an intervention. Education campaigns would reduce type 2 diabetes prevalence, but it would remain highest among women with obesity at 27.7% (CI: 26.2%-29.2%). The intervention would reduce hypertension prevalence among White women by 4.7 percentage points to 38.0% (CI: 36.4%-39.7%). For Black women in the intervention, the 2049 hypertension prevalence would be 52.6% (CI: 50.7%-54.5%). Results for men and women were similar. CONCLUSIONS: Long-term health education campaigns can reduce obesity-related disease. All population groups benefit, but they would not substantially narrow cardiometabolic health disparities.

Diet Quality in the United States Improved during the Great Recession and Deteriorated During Economic Recovery.

BACKGROUND: Macroeconomic changes are associated with population health outcomes, such as mortality, accidents, and alcohol use. Diet quality is a risk or protective factor that could be influenced by economic conditions. OBJECTIVE: This study examined the trajectory of diet quality measured by the Healthy Eating Index 2015 before, during, and after the 2008-2009 Great Recession. DESIGN: Repeated cross-sectional survey data from the National Health and Nutrition Examination Survey were analyzed. PARTICIPANTS/SETTING: The analytic sample included 48,679 adults who completed at least one dietary recall from National Health and Nutrition Examination Survey 1999-2018. MAIN OUTCOME MEASURES: Diet quality was assessed with a 24-hour dietary recall to calculate the Healthy Eating Index 2015 total scores, a measure of the conformance with the 2015-2020 Dietary Guidelines for Americans. STATISTICAL ANALYSES PERFORMED: Least squares regression was used to adjust for demographic changes across waves. RESULTS: Diet quality improved noticeably during the Great Recession and deteriorated as economic conditions improved. CONCLUSIONS: Deteriorating economic circumstances may constrain choices, but that does not necessarily imply a worsening of dietary quality. During the Great Recession, American diets became more consistent with Dietary Guidelines for Americans recommendations, possibly because of a shift toward food prepared at home instead of prepared food bought away from home.

Diet quality improvement and 30-year population health and economic outcomes: a microsimulation study.

OBJECTIVE: Diets closer aligned with nutritional guidelines could lower the risk of several chronic conditions and improve economic outcomes, such as employment and healthcare costs. However, little is known about the range, order of magnitude and timing of these potential effects. DESIGN: We used a microsimulation approach to predict US population changes over 30 years in health and economic outcomes that could result from a substantial (but not impossible) improvement in diet quality - an improvement from the third to the fifth quintile of US scores on the Alternate Healthy Eating Index, 2010 version. SETTING: Risk ratios from the literature for diabetes, heart disease and stroke were used to modify the Future Adult Model (FAM) to simulate outcomes from a higher-quality diet. Model parameter uncertainty was assessed using bootstrap and sensitivity analysis examined the variation in published risk ratios. PARTICIPANTS: FAM simulates outcomes for the US adult population aged 25 and older. RESULTS: Improved diet quality initially leads to very small changes in chronic disease prevalence, but these accumulate over time. If diets improved beginning in 2019, after 30 years diabetes prevalence could be reduced by 5·9 million cases (11·5 %), heart disease prevalence by 4·0 million cases (7·2 %) and stroke prevalence by 1·9 million cases (10·3 %). These reductions in disease prevalence would be accompanied that same year by fewer deaths (88 000) and healthcare cost savings of $144·0 billion (2019 USD). CONCLUSIONS: This microsimulation study suggests that improvements in diet are likely to improve health and economic population outcomes over time.

Free Time and Physical Activity Among Americans 15 Years or Older: Cross-Sectional Analysis of the American Time Use Survey.

INTRODUCTION: Many Americans fail to meet physical activity guidelines. We investigated whether this failure is due in part to a lack of free time. METHODS: We analyzed data from the American Time Use Survey, 2014 through 2016, with 32,048 respondents aged 15 years or older, categorizing every activity during a 24-hour period. Free or leisure time includes time spent socializing, being entertained, in sports and recreation activities, volunteering, in religious activities, taking classes for personal interest, and in associated travel time. Working in the labor market, education (unless only for personal interest), household work and home production (cooking, cleaning, child care, shopping), or self-care (sleeping, eating, grooming) are not free time. We stratified by sociodemographic characteristics, health, and body mass index, and we calculated descriptive statistics adjusted for the multistage sampling design. RESULTS: Americans averaged more than 5 hours (>300 minutes) of free time per day; no subgroup reported having less than 4.5 hours (270 minutes) of free time. Men had more free time (mean [standard deviation], 356 [3] min/d) and spent more on leisure time physical activity (mean [SD], 24 [3] min/d) than women did (free time mean [SD], 318 [2] min/d, P < .001; and leisure time physical activity mean [SD], 14 [1] min/d, P < .001). Compared with those with a higher income and a college education, those with income below 185% of federal poverty guidelines and those with a high school education reported more free time but spent more time on television, movies, and other screen time and less on physical activity (all comparisons P < .001). CONCLUSION: Lack of free time is not responsible for low levels of leisure time physical activity at the population level.

Obesity Prevention Interventions and Implications for Energy Balance in the United States and Mexico: A Systematic Review of the Evidence and Meta-Analysis.

OBJECTIVE: Obesity is preventable and yet continues to be a major risk factor for chronic disease. Multiple prevention approaches have been proposed across multiple settings where people live, work, learn, worship, and play. This review searched the vast literature on obesity prevention interventions to assess their effects on daily energy consumed and energy expended. METHODS: This systematic review (PROSPERO registration CRD42017077083) searched seven databases for systematic reviews and studies reporting energy intake and expenditure. Two independent reviewers screened 5,977 citations; data abstraction supported an evidence map, comprehensive evidence tables, and meta-analysis; critical appraisal assessed risk of bias; and the quality of evidence was evaluated using Grading of Recommendations Assessment, Development and Evaluation (GRADE). RESULTS: Hundreds of published reviews were identified. However, few studies reported on energy intake and expenditure to determine intervention success. Ninety-nine studies across all intervention domains were identified. Few areas demonstrated statistically significant effects across studies; school-based approaches and health care initiatives reduced energy consumed, education reduced energy consumed and increased energy expended, and social-group approaches increased energy expenditure. CONCLUSIONS: Despite the amount of research on obesity prevention interventions, very few studies have provided relevant information on energy intake and expenditure, two factors determining weight gain. Future research needs to fill this gap to identify successful public health policies.

A Cash-back Rebate Program for Healthy Food Purchases in South Africa: Selection and Program Effects in Self-reported Diet Patterns.

OBJECTIVES: A South African insurer launched a rebate program for healthy food purchases for its members, but only available in program-designated supermarkets. To eliminate selection bias in program enrollment, we estimated the impact of subsidies in nudging the population towards a healthier diet using an instrumental variable approach. METHODS: Data came from a health behavior questionnaire administered among members in the health promotion program. Individual and supermarket addresses were geocoded and differential distances from home to program-designated supermarkets versus competing supermarkets were calculated. Bivariate probit and linear instrumental variable models were performed to control for likely unobserved selection biases, employing differential distances as a predictor of program enrollment. RESULTS: For regular fast-food, processed meat, and salty food consumption, approximately two-thirds of the difference between participants and nonparticipants was attributable to the intervention and one-third to selection effects. For fruit/ vegetable and fried food consumption, merely one-eighth of the difference was selection. The rebate reduced regular consumption of fast food by 15% and foods high in salt/sugar and fried foods by 22%- 26%, and increased fruit/vegetable consumption by 21% (0.66 serving/day). CONCLUSIONS: Large population interventions are an essential complement to laboratory experiments, but selection biases require explicit attention in evaluation studies conducted in naturalistic settings.

Seasonal cycles in food purchases and changes in BMI among South Africans participating in a health promotion programme.

OBJECTIVE: Improving diet quality is a key factor for promoting population health. Social norms can support or undermine these efforts. The present study aimed to investigate the relationship between seasonal variation in food purchases and BMI. DESIGN: The study population comprises members of a South African health promotion programme. Data come from scanner data of food purchases by 400 000 enrolled households at supermarkets and repeated individual surveys (about 500 000 participants) between 2009 and 2013. RESULTS: Members in the health promotion programme spent 16·7 % of total food expenditure on nutritionally undesirable foods (sugar-sweetened beverages, candy, ice cream, etc.) and 24·7 % on healthy foods (fruit/vegetables, whole grains, non-fat dairy, etc.). Fruits and vegetables accounted for 13·5 % of purchases (half of all healthy food spending). Yet there were pronounced seasonal variations, with December being the peak month for unhealthy food purchases, which were 40 % higher than in January. This holiday peak was associated with short-term weight gain, but average body mass did not revert to pre-holiday levels. From 2009 to 2013, respondents gained about 0·13 BMI units per year (0·43 kg for men, 0·30 for women). From November to January alone, the increase was 0·1 BMI units for men (0·35 kg) and 0·8 BMI units for women (0·20 kg). CONCLUSIONS: Purchases of nutritionally undesirable foods peak in December and are accompanied by weight gain from November to January. Despite weight loss after January, the November to January weight gain accounts for 60-70 % of the annual gain.

Neighborhood Food Environment, Diet, and Obesity Among Los Angeles County Adults, 2011.

INTRODUCTION: The objective of this study was to examine whether an association exists between the number and type of food outlets in a neighborhood and dietary intake and body mass index (BMI) among adults in Los Angeles County. We also assessed whether this association depends on the geographic size of the food environment. METHODS: We analyzed data from the 2011 Los Angeles County Health Survey. We created buffers (from 0.25 to 3.0 miles in radius) centered in respondents' residential addresses and counted the number of food outlets by type in each buffer. Dependent variables were weekly intake of fruits and vegetables, sugar-sweetened beverages, and fast food; BMI; and being overweight (BMI ≥25.0 kg/m(2)) or obese (BMI ≥30.0 kg/m(2)). Explanatory variables were the number of outlets classified as fast-food outlets, convenience stores, small food stores, grocery stores, and supermarkets. Regressions were estimated for all sets of explanatory variables and buffer size combinations (150 total effects). RESULTS: Only 2 of 150 effects were significant after being adjusted for multiple comparisons. The number of fast-food restaurants in nonwalkable areas (in a 3.0-mile radius) was positively associated with fast-food consumption, and the number of convenience stores in a walkable distance (in a 0.25-mile radius) was negatively associated with obesity. DISCUSSION: Little evidence was found for associations between proximity of respondents' homes to food outlets and dietary intake or BMI among adults in Los Angeles County. A possible explanation for the null finding is that shopping patterns are weakly related to neighborhoods in Los Angeles County because of motorized transportation.

Diet and obesity in Los Angeles County 2007-2012: Is there a measurable effect of the 2008 "Fast-Food Ban"?

We evaluate the impact of the "Los Angeles Fast-Food Ban", a zoning regulation that has restricted opening/remodeling of standalone fast-food restaurants in South Los Angeles since 2008. Food retail permits issued after the ban are more often for small food/convenience stores and less often for larger restaurants not part of a chain in South Los Angeles compared to other areas; there are no significant differences in the share of new fast-food chain outlets, other chain restaurants, or large food markets. About 10% of food outlets are new since the regulation, but there is little evidence that the composition has changed differentially across areas. Data from the California Health Interview Survey show that fast-food consumption and overweight/obesity rates have increased from 2007 to 2011/2012 in all areas. The increase in the combined prevalence of overweight and obesity since the ban has been significantly larger in South Los Angeles than elsewhere. A positive development has been a drop in soft drink consumption since 2007, but that drop is of similar magnitude in all areas.

Impact of a patient incentive program on receipt of preventive care.

OBJECTIVES: Patient financial incentives are being promoted as a mechanism to increase receipt of preventive care, encourage healthy behavior, and improve chronic disease management. However, few empirical evaluations have assessed such incentive programs. STUDY DESIGN: In South Africa, a private health plan has introduced a voluntary incentive program which costs enrollees approximately $20 per month. In the program, enrollees earn points when they receive preventive care. These points translate into discounts on retail goods such as airline tickets, movie tickets, or cell phones. METHODS: We chose 8 preventive care services over the years 2005 to 2011 and compared the change between those who entered the incentive program and those that did not. We used multivariate regression models with individual random effects to try to address selection bias. RESULTS: Of the 4,186,047 unique individuals enrolled in the health plan, 65.5% (2,742,268) voluntarily enrolled in the incentive program. Joining the incentive program was associated with statistically higher odds of receiving all 8 preventive care services. The odds ratio (and estimated percentage point increase) for receipt of cholesterol testing was 2.70 (8.9%); glucose testing 1.51 (4.7%); glaucoma screening 1.34 (3.9%); dental exam 1.64 (6.3%); HIV test 3.47 (2.6%); prostate specific antigen testing 1.39 (5.6%); Papanicolaou screening 2.17 (7.0%); and mammogram 1.90 (3.1%) (P < .001 for all 8 services). However, preventive care rates among those in the incentive program was still low. CONCLUSIONS: Voluntary participation in a patient incentive program was associated with a significantly higher likelihood of receiving preventive care, though receipt of preventive care among those in the program was still lower than ideal.

Proximity to urban parks and mental health.

BACKGROUND: Urban parks have received attention in recent years as a possible environmental factor that could encourage physical activity, prevent obesity, and reduce the incidence of chronic conditions. Despite long hypothesized benefits of parks for mental health, few park studies incorporate mental health measures. AIMS OF THE STUDY: To test the association between proximity to urban parks and psychological distress. METHODS: Cross-sectional analysis of individual health survey responses. Data were collected for a study of capital improvements of neighborhood parks in Los Angeles. A survey was fielded on a sample of residential addresses, stratified by distance from the park (within 400m, 800m, 1.6 km, and 3.2km; N=1070). We used multiple regression to estimate the relationship between the psychological distress as measured by the MHI-5 (outcome variable) and distance to parks (main explanatory variable), controlling for observed individual characteristics. RESULTS: Mental health is significantly related to residential distance from parks, with the highest MHI-5 scores among residents within short walking distance from the park (400m) and decreasing significantly over the next distances. The number of visits and physical activity minutes are significantly and independently related to distance, although controlling for them does not reduce the association between distance and mental health. DISCUSSION AND LIMITATIONS: This paper provides a new data point for an arguably very old question, but for which empirical data are sparse for the US. A nearby urban park is associated with the same mental health benefits as decreasing local unemployment rates by 2 percentage points, suggesting at least the potential of environmental interventions to improve mental health. The analysis is cross-sectional, making it impossible to control for important confounders, including residential selection. IMPLICATIONS FOR HEALTH POLICY: Mental health policy has traditionally focused on individual-centered interventions. Just as health policy for preventable chronic illnesses has shifted attention to modifiable environmental determinants, population mental health may benefit substantially from environmental interventions. IMPLICATIONS FOR FUTURE RESEARCH: Policy evaluations should incorporate mental health measures when assessing neighborhood improvement programs and physical environments. Many recent and ongoing studies have excluded mental health measure in the belief that they are too burdensome for respondents or irrelevant. If a causal relationship is confirmed, then ameliorating neighborhood conditions and physical environments could represent a scalable way to improve mental health issues for large populations.

Obesity and economic environments.

This review summarizes current understanding of economic factors during the obesity epidemic and dispels some widely held, but incorrect, beliefs. Rising obesity rates coincided with increases in leisure time (rather than increased work hours), increased fruit and vegetable availability (rather than a decline in healthier foods), and increased exercise uptake. As a share of disposable income, Americans now have the cheapest food available in history, which fueled the obesity epidemic. Weight gain was surprisingly similar across sociodemographic groups or geographic areas, rather than specific to some groups (at every point in time; however, there are clear disparities). It suggests that if one wants to understand the role of the environment in the obesity epidemic, one needs to understand changes over time affecting all groups, not differences between subgroups at a given time. Although economic and technological changes in the environment drove the obesity epidemic, the evidence for effective economic policies to prevent obesity remains limited. Taxes on foods with low nutritional value could nudge behavior toward healthier diets, as could subsidies/discounts for healthier foods. However, even a large price change for healthy foods could close only part of the gap between dietary guidelines and actual food consumption. Political support has been lacking for even moderate price interventions in the United States and this may continue until the role of environmental factors is accepted more widely. As opinion leaders, clinicians play an important role in shaping the understanding of the causes of obesity.

Changes in the energy and sodium content of main entrées in US chain restaurants from 2010 to 2011.

BACKGROUND: The food environment shapes individual diets, and as food options change, energy and sodium intake may also shift. Understanding whether and how restaurant menus evolve in response to labeling laws and public health pressures could inform future efforts to improve the food environment. OBJECTIVES: To track changes in the energy and sodium content of US chain restaurant main entrées between spring 2010 (when the Affordable Care Act was passed, which included a federal menu labeling requirement) and spring 2011. DESIGN: Nutrition information was collected from top US chain restaurants' websites, comprising 213 unique brands. Descriptive statistics and regression analysis evaluated change across main entrées overall and compared entrées that were added, removed, and unchanged. Tests of means and proportions were conducted for individual restaurant brands to see how many made significant changes. Separate analyses were conducted for children's menus. RESULTS: Mean energy and sodium did not change significantly overall, although mean sodium was 70 mg lower across all restaurants in added vs removed menu items at the 75th percentile. Changes were specific to restaurant brands or service model: family-style restaurants reduced sodium among higher-sodium entrées at the 75th percentile, but not on average, and entrées still far exceeded recommended limits. Fast-food restaurants decreased mean energy in children's menu entrées by 40 kcal. A few individual restaurant brands made significant changes in energy or sodium, but the vast majority did not, and not all changes were in the healthier direction. Among those brands that did change, there were slightly more brands that reduced energy and sodium compared with those that increased it. CONCLUSIONS: Industry marketing and pledges may create a misleading perception that restaurant menus are becoming substantially healthier, but both healthy and unhealthy menu changes can occur simultaneously. Our study found no meaningful changes overall across a 1-year time period. Longer-term studies are needed to track changes over time, particularly after the federal menu labeling law is implemented.

The obesity epidemic and changes in self-report biases in BMI.

OBJECTIVE: To assess time trends in measurement error of BMI and the sensitivity/specificity of classifying weight status in the United States by analyzing the difference in BMI between self-reported and measured height and weight. DESIGN AND METHODS: Data from 18,394 respondents aged 20-89 years from the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2008 were analyzed. Multiple linear regression and logistic regression models estimated trends in reporting bias and misclassification of weight status by BMI categories, sex, age, and racial/ethnic groups, adjusting for the sampling design. RESULTS: We find no evidence that there are time trends in the accuracy of self-report by BMI categories, sex, age, or racial/ethnic groups. The well-known downward bias in self-report has remained stable over the last decade; approximately one in six to seven obese individuals were misclassified as nonobese due to underestimation of BMI. CONCLUSION: Increases in obesity rates based on self-reported height and weight are likely to reflect actual weight increases and are not inflated by changes in reporting accuracy.

A cash-back rebate program for healthy food purchases in South Africa: results from scanner data.

BACKGROUND: Improving diet quality is a key health promotion strategy. There is much interest in the role of prices and financial incentives to encourage healthy diet, but no data from large population interventions. PURPOSE: This study examines the effect of a price reduction for healthy food items on household grocery shopping behavior among members of South Africa's largest health plan. METHODS: The HealthyFood program provides a cash-back rebate of up to 25% for healthy food purchases in over 400 designated supermarkets across all provinces in South Africa. Monthly household supermarket food purchase scanner data between 2009 and 2012 are linked to 170,000 households (60% eligible for the rebate) with Visa credit cards. Two approaches were used to control for selective participation using these panel data: a household fixed-effect model and a case-control differences-in-differences model. RESULTS: Rebates of 10% and 25% for healthy foods are associated with an increase in the ratio of healthy to total food expenditure by 6.0% (95% CI=5.3, 6.8) and 9.3% (95% CI=8.5, 10.0); an increase in the ratio of fruit and vegetables to total food expenditure by 5.7% (95% CI=4.5, 6.9) and 8.5% (95% CI=7.3, 9.7); and a decrease in the ratio of less desirable to total food expenditure by 5.6% (95% CI=4.7, 6.5) and 7.2% (95% CI=6.3, 8.1). CONCLUSIONS: Participation in a rebate program for healthy foods led to increases in purchases of healthy foods and to decreases in purchases of less-desirable foods, with magnitudes similar to estimates from U.S. time-series data.

Neighborhood food outlets, diet, and obesity among California adults, 2007 and 2009.

INTRODUCTION: Varying neighborhood definitions may affect research on the association between food environments and diet and weight status. The objective of this study was to examine the association between number and type of neighborhood food outlets and dietary intake and body mass index (BMI) measures among California adults according to the geographic size of a neighborhood or food environment. METHODS: We analyzed data from 97,678 respondents aged 18 years or older from the 2007 and 2009 California Health Interview Survey through multivariable regression models. Outcome variables were BMI, weight status of a BMI of 25.0 or more and a BMI of 30.0 or more, and the number of times per week the following were consumed: fruits, vegetables, sugar-sweetened soft drinks, fried potatoes, and fast food. Explanatory variables were the number of fast-food restaurants, full-service restaurants, convenience stores, small food stores, grocery stores, and large supermarkets within varying distances (0.25 to 3.0 miles) from the survey respondent's residence. We adopted as a measure of walking distance a Euclidean distance within 1 mile. Control variables included sociodemographic and economic characteristics of respondents and neighborhoods. RESULTS: Food outlets within walking distance (≤ 1.0 mile) were not strongly associated with dietary intake, BMI, or probabilities of a BMI of 25.0 or more or a BMI of 30.0 or more. We found significant associations between fast-food outlets and dietary intake and between supermarkets and BMI and probabilities of a BMI of 25.0 or more and a BMI of 30.0 or more for food environments beyond walking distance (> 1.0 mile). CONCLUSION: We found no strong evidence that food outlets near homes are associated with dietary intake or BMI. We replicated some associations reported previously but only for areas that are larger than what typically is considered a neighborhood. A likely reason for the null finding is that shopping patterns are weakly related, if at all, to neighborhoods in the United States because of access to motorized transportation.