Food prices and obesity: a review

Health Economic Aspects of Childhood Excess Weight: A Structured Review

An economic perspective is crucial to understand the broad consequences of childhood excess weight (CEW). These can manifest in the form of elevated health care and societal costs, impaired health status, or inefficiencies in the allocation of resources targeted at its prevention, management, or treatment. Although existing systematic reviews provide summaries of distinct economic research strands covering CEW, they have a restricted focus that overlooks relevant evidence. The overarching aim of this structured review was to update and enhance recent key reviews of four strands of economic evidence in this area, namely, (1) economic costs associated with CEW, (2) health utilities associated with CEW, (3) economic evaluations of interventions targeting CEW, and (4) economic determinants and broader consequences of CEW. Our de novo searches identified six additional studies for the first research strand, five studies for the second, thirty-one for the third, and two for the fourth. Most studies were conducted in a small number of high-income countries. Our review highlights knowledge gaps across all the research strands. Evidence from this structured review can act as data input into future economic evaluations in this area and highlights areas where future economic research should be targeted.

Impacts of bariatric surgery in health outcomes and health care costs in Brazil: Interrupted time series analysis of multi-panel data

Background

The increasing burden of obesity generates significant socioeconomic impacts for individuals, populations, and national health systems worldwide. The literature on impacts and cost-effectiveness of obesity-related interventions for prevention and treatment of moderate to severe obesity indicate that bariatric surgery presents high costs associated with high effectiveness in improving health status referring to certain outcomes; however, there is a lack of robust evidence at an individual-level estimation of its impacts on multiple health outcomes related to obesity comorbidities.

Methods

The study encompasses a single-centre retrospective longitudinal analysis of patient-level data using micro-costing technique to estimate direct health care costs with cost-effectiveness for multiple health outcomes pre-and post-bariatric surgery. Data from 114 patients who had bariatric surgery at the Hospital of Clinics of the University of Sao Paulo during 2018 were investigated through interrupted time-series analysis with generalised estimating equations and marginal effects, including information on patients' characteristics, lifestyle, anthropometric measures, hemodynamic measures, biochemical exams, and utilisation of health care resources during screening (180 days before) and follow-up (180 days after) of bariatric surgery.

Results

The preliminary statistical analysis showed that health outcomes presented improvement, except cholesterol and VLDL, and overall direct health care costs increased after the intervention. However, interrupted time series analysis showed that the rise in health care costs is attributable to the high cost of bariatric surgery, followed by a statistically significant decrease in post-intervention health care costs. Changes in health outcomes were also statistically significant in general, except in cholesterol and LDL, leading to significant improvements in patients' health status after the intervention.

Conclusions

Trends multiple health outcomes showed statistically significant improvements in patients' health status post-intervention compared to trends pre-intervention, resulting in reduced direct health care costs and the burden of obesity.

Association between the price of ultra-processed foods and obesity in Brazil

BACKGROUND AND AIMS

To estimate the relationship between the price of ultra-processed foods and prevalence of obesity in Brazil and examine whether the relationship differed according to socioeconomic status.

METHODS AND RESULTS

Data from the national Household Budget Survey from 2008/09 (n = 55 570 households, divided in 550 strata) were used. Weight and height of all individuals were used. Weight was measured by using portable electronic scales (maximum capacity of 150 kg). Height (or length) was measured using portable stadiometers (maximum capacity: 200 cm long) or infant anthropometers (maximum capacity: 105 cm long). Multivariate regression models (log-log) were used to estimate price elasticity. An inverse association was found between the price of ultra-processed foods (per kg) and the prevalence of overweight (Body mass index (BMI) ≥25 kg/m²) and obesity (BMI ≥30 kg/m²) in Brazil. The price elasticity for ultra-processed foods was -0.33 (95% CI: -0.46; -0.20) for overweight and -0.59 (95% CI: -0.83; -0.36) for obesity. This indicated that a 1.00% increase in the price of ultra-processed foods would lead to a decrease in the prevalence of overweight and obesity of 0.33% and 0.59%, respectively. For the lower income group, the price elasticity for price of ultra-processed foods was -0.34 (95% CI: -0.50; -0.18) for overweight and -0.63 (95% CI: -0.91; -0.36) for obesity.

CONCLUSION

The price of ultra-processed foods was inversely associated with the prevalence of overweight and obesity in Brazil, mainly in the lowest socioeconomic status population. Therefore, the taxation of ultra-processed foods emerges as a prominent tool in the control of obesity.

Association of Fast Food and Supermarket Density with Neonatal Outcomes of Pregnancies Affected by Gestational Diabetes

OBJECTIVE

To measure the association of fast food density (FFD) and supermarket density (SD) with adverse neonatal outcomes in pregnancies with gestational diabetes mellitus (GDM).

STUDY DESIGN

This was a retrospective cohort study of women with GDM who delivered at a tertiary care center in a large metropolitan area (1/2010-2/2016). ZIP codes were used to link women with surrounding food environment. FFD and SD were calculated as the number of establishments per 100,000 residents for each ZIP code and classified into quartiles. Quartile 1 represented lowest FFD or SD. Four neonatal outcomes were assessed: large for gestational age (LGA) neonate, shoulder dystocia, neonatal hypoglycemia, and neonatal intensive care unit admission > 3 days. Bivariable and multivariable analyses estimated associations of FFD and SD with outcomes.

RESULTS

A total of 2,373 women met eligibility criteria. Insurance, race/ethnicity, language, and body mass index differed between quartiles, although GDM type did not. High FFD was associated with lower odds of LGA but not with other outcomes. Low SD and FFD:SD ratios were not associated with any outcomes.

CONCLUSION

Among women with GDM, high FFD was associated with some neonatal outcomes, but low SD and FFD:SD ratio was not. Food environment may not be the only social determinant of neonatal outcomes in pregnancies with GDM.

Corporations' use and misuse of evidence to influence health policy: a case study of sugar-sweetened beverage taxation

Background

Sugar sweetened beverages (SSB) are a major source of sugar in the diet. Although trends in consumption vary across regions, in many countries, particularly LMICs, their consumption continues to increase. In response, a growing number of governments have introduced a tax on SSBs. SSB manufacturers have opposed such taxes, disputing the role that SSBs play in diet-related diseases and the effectiveness of SSB taxation, and alleging major economic impacts. Given the importance of evidence to effective regulation of products harmful to human health, we scrutinised industry submissions to the South African government’s consultation on a proposed SSB tax and examined their use of evidence.

Results

Corporate submissions were underpinned by several strategies involving the misrepresentation of evidence. First, references were used in a misleading way, providing false support for key claims. Second, raw data, which represented a pliable, alternative evidence base to peer reviewed studies, was misused to dispute both the premise of targeting sugar for special attention and the impact of SSB taxes on SSB consumption. Third, purposively selected evidence was used in conjunction with other techniques, such as selective quoting from studies and omitting important qualifying information, to promote an alternative evidential narrative to that supported by the weight of peer-reviewed research. Fourth, a range of mutually enforcing techniques that inflated the effects of SSB taxation on jobs, public revenue generation, and gross domestic product, was used to exaggerate the economic impact of the tax. This “hyperbolic accounting” included rounding up figures in original sources, double counting, and skipping steps in economic modelling.

Conclusions

Our research raises fundamental questions concerning the bona fides of industry information in the context of government efforts to combat diet-related diseases. The beverage industry’s claims against SSB taxation rest on a complex interplay of techniques, that appear to be grounded in evidence, but which do not observe widely accepted approaches to the use of either scientific or economic evidence. These techniques are similar, but not identical, to those used by tobacco companies and highlight the problems of introducing evidence-based policies aimed at managing the market environment for unhealthful commodities.

Electronic supplementary material

The online version of this article (10.1186/s12992-019-0495-5) contains supplementary material, which is available to authorized users.

Susceptibility to price discounting of soda by neighbourhood educational status: an ecological analysis of disparities in soda consumption using point-of-purchase transaction data in Montreal, Canada

Introduction

Price discounting is a marketing tactic used frequently by food industries and retailers, but the extent to which education modifies the effect of discounting on the purchasing of unhealthy foods has received little attention. We investigated whether there was a differential association of price discounting of soda with store-level soda purchasing records between 2008 and 2013 by store-neighbourhood education in Montreal, Canada.

Methods

Using data on grocery purchase transactions from a sample of supermarkets, pharmacies, supercentres and convenience stores, we performed an ecological time-series analysis, modelling weekly store-level sales of soda as a function of store-level price discounting, store- and neighbourhood-level confounders and an interaction term between discounting and categorical education in the neighbourhood of each store.

Results

Analysis by store type (n = 18 743, 12 437, 3965 and 49 533 store-weeks for superstores, pharmacies, supercentres and convenience stores, respectively) revealed that the effect measure modification of discounting by neighbourhood education on soda purchasing was lower in stores in the more educated neighbourhoods, most notably in pharmacies: -0.020 [95% confidence interval (CI): -0.028, -0.012] and -0.038 (95% CI: -0.051, -0.025), for middle- and high-education categories, respectively). Weaker effect modification was observed in convenience stores. There was no evidence of effect modification in supercentres or superstores.

Conclusions

Price discounting is an important environmental risk factor for soda purchasing and can widen education inequalities in excess sugar intake across levels of education. Interventions to regulate price discounting warrant further investigation as a public health strategy to improve population nutrition, particularly in lower-education neighbourhoods.

"There is no way to avoid the first bite": A qualitative investigation of addictive-like eating in treatment-seeking Brazilian women and men

There has been polarizing debate on addictive-like eating in recent years. To move toward valid definition and measurement of this construct, qualitative research describing individuals' experiences is needed. The present study explored how Brazilian men and women define and experience addictive-like eating. Interviews were conducted with 7 men and 8 women (M_age = 46.6 years, M_BMI = 35.43 kg/m²) seeking treatment for addictive-like eating. Thematic analysis of interviews identified three saturated, overarching themes describing participants' conceptualizations of the (1) characteristics, (2) causal factors, and (3) consequences of addictive-like eating. Lack of control was a key characteristic of addictive-like eating described by all participants. A causal factor which most participants described was emotional eating. Consequences included emotional, interpersonal, occupational, and health-related impairments which appeared primarily related to weight gain, rather than to the pattern of addictive-like eating itself. These results are largely consistent with those of previous qualitative studies. Importantly, the symptoms described by our participants and in previous qualitative studies may be inadequately captured by existing self-report questionnaires designed to assess addictive-like eating. To address this potential limitation, we provide recommendations for assessing the full range of possible addictive-like eating symptoms.

Food price trends in South Korea through time series analysis

OBJECTIVES

This study analyzed the relative time trends of prices of healthy versus unhealthy foods in South Korea for the 20 years from 1995 to 2015.

STUDY DESIGN

Time series analysis was used.

METHODS

We analyzed price trends of selected food items in the food groups of grains, vegetables, meats, sweets, spices, fast foods, and non-alcoholic beverages. We obtained nominal prices from the monthly reports of the 2006 Consumer Price Survey for representative items in each food group.

RESULTS

The real price of processed meat increased by 1.2 percentage points less than the overall Consumer Price Index (CPI) increase, whereas beef prices increased by 2.4 percentage points more than the CPI increase. The price of soda was cheaper than that of other non-alcoholic beverages, whereas the real prices of milk showed statistically significantly larger yearly increases (by 1.4 percentage points, respectively) than that of the CPI. The yearly increases in the real prices of pizza, hamburgers, and fried chicken-three representative fast-food items that were mostly consumed by eating out or through home delivery-were statistically significantly less than those of the CPI (by 1.5, 1.4, and 0.3 percentage points, respectively).

CONCLUSIONS

Our results show that relatively healthy foods showed higher real price increases than the CPI increase, whereas the opposite occurred for unhealthy foods.

Cancers Due to Excess Weight, Low Physical Activity, and Unhealthy Diet

BACKGROUND

Excess weight, low physical activity, low intakes of dietary fiber, fruits, and vegetables, and high meat and salt intake increase cancer risk.

METHODS

Numbers and proportions (population-attributable fractions, PAF) of incident cancer cases in Germany in 2018 attributable to these factors were estimated by sex and age groups for ages 35 to 84 years using population projections, national cancer incidence and exposure data, and published risk estimates.

RESULTS

Estimated numbers (percentages) of attributable cancers were 30 567 (7%) for excess weight, 27 081 (6%) for low physical activity, 14 474 (3%) for low dietary fiber intake, 9447 (2%) for low fruit and vegetable consumption, 9454 (2%) and 1687 (0.4%) for processed meat and high red meat consumption, respectively, and 1204 (0.3%) for high salt intake. Excess weight substantially contributed to endometrial, renal, and liver cancer (PAF = 24 to 35%). Low physical activity contributed to endometrial, renal, and lung cancer (PAF = 15 to 19%), and dietary factors mainly contributed to colorectal, breast, and lung cancer (PAF = 9 to 16%).

CONCLUSION

A considerable proportion of cancer cases are attributable to excess weight, physical inactivity, and unhealthy dietary habits. Major prevention efforts are needed to reduce the cancer incidence attributable to these avoidable factors.

Neighborhood price of healthier food relative to unhealthy food and its association with type 2 diabetes and insulin resistance: The multi-ethnic study of atherosclerosis

This study examined the association between the price of healthier food relative to unhealthy food and type 2 diabetes prevalence, incidence and insulin resistance (IR). Data came from the Multi-Ethnic Study of Atherosclerosis exam 5 administered 2010-2012 (exam 4, five years prior, was used only for diabetes incidence) and supermarket food/beverage prices derived from Information Resources Inc. For each individual, average price of a selection of healthier foods, unhealthy foods and their ratio was computed for supermarkets within 3miles of the person's residential address. Diabetes status was confirmed at each exam and IR was assessed via the homeostasis model assessment index. Multivariable-adjusted logistic, modified Poisson and linear regression models were used to model diabetes prevalence, incidence and IR, respectively as a function of price and covariates; 2353 to 3408 participants were included in analyses (depending on the outcome). A higher ratio of healthy-to-unhealthy neighborhood food price was associated with greater IR (4.8% higher HOMA-IR score for each standard deviation higher price ratio [95% CI -0.2% to 10.1%]) after adjusting for region, age, gender, race/ethnicity, family history of diabetes, income/wealth index, education, smoking status, physical activity, and neighborhood socioeconomic status. No association with diabetes incidence (relative risk=1.11, 95% CI 0.85 to 1.44) or prevalence (odds ratio=0.95, 95% CI 0.81 to 1.11) was observed. Higher neighborhood prices of healthier food relative to unhealthy food were positively associated with IR, but not with either diabetes outcome. This study provides new insight into the relationship between food prices with IR and diabetes.

Aquisição domiciliar de refrigerantes e de biscoitos reduz o efeito de uma intervenção de promoção de frutas e hortaliças

Resumo: O presente estudo examina a influência do aumento da disponibilidade intradomiciliar de refrigerantes e biscoitos sobre os efeitos de uma intervenção de promoção do consumo de frutas e hortaliças. Foram analisados os dados de 70 famílias que viviam em comunidades de baixa renda na cidade do Rio de Janeiro, Brasil, que foram selecionadas por meio de uma amostra probabilística estratificada e completaram registro alimentar de 30 dias antes e depois da intervenção. A intervenção contribuiu para um aumento significativo na disponibilidade intradomiciliar de frutas e hortaliças (+2,7 p.p.; IC95%: 1,5; 4,0), superando a tendência de estagnação na população brasileira. Já a aquisição de refrigerantes e biscoitos, que não foi objeto da intervenção, acompanhou a tendência crescente de consumo destes produtos (+5,8 p.p.; IC95%: 3,3; 8,4). As famílias que aumentaram a aquisição de refrigerantes e biscoitos apresentaram menores aumentos, ou decréscimos, na aquisição de frutas e hortaliças (p < 0,05) e tiveram uma chance quase quatro vezes menor de experimentar algum aumento na disponibilidade intradomiciliar de frutas e hortaliças.

Changes in regional body composition over 8 years in a randomized lifestyle trial: The look AHEAD study

OBJECTIVE

To test the hypothesis that an 8-year intensive lifestyle intervention (ILI) suppresses aging-dependent changes in regional lean mass (LM) and fat mass (FM) among people with overweight/obesity and type 2 diabetes.

METHODS

Regional body composition was measured by dual-energy X-ray absorptiometry within a subset of 1,019 volunteers (45-75 years old) in the Look AHEAD study randomized to ILI or diabetes support and education (DSE). The ILI goal was to achieve and maintain ≥7% weight loss through increased physical activity and reduced caloric intake.

RESULTS

Over 8 years, the DSE group exhibited a linear loss of LM and FM. During year 1, the ILI group lost LM and FM. Between years 1 and 8, the ILI group regained most FM in all regions; regional LM converged with that of the DSE group; the percent of LM loss was greater for the leg than for the trunk. Among both groups, regional LM and FM change was proportional to the size of the region, trunk > leg > arm.

CONCLUSIONS

Aging-dependent LM losses, particularly in the leg region, were not suppressed by ILI. The long-term consequences of rapid LM and FM loss and subsequent regain mostly as fat are unknown.

Study protocol: combining experimental methods, econometrics and simulation modelling to determine price elasticities for studying food taxes and subsidies (The Price ExaM Study)

Background

There is a need for accurate and precise food price elasticities (PE, change in consumer demand in response to change in price) to better inform policy on health-related food taxes and subsidies.

Methods/Design

The Price Experiment and Modelling (Price ExaM) study aims to: I) derive accurate and precise food PE values; II) quantify the impact of price changes on quantity and quality of discrete food group purchases and; III) model the potential health and disease impacts of a range of food taxes and subsidies. To achieve this, we will use a novel method that includes a randomised Virtual Supermarket experiment and econometric methods. Findings will be applied in simulation models to estimate population health impact (quality-adjusted life-years [QALYs]) using a multi-state life-table model. The study will consist of four sequential steps:

We generate 5000 price sets with random price variation for all 1412 Virtual Supermarket food and beverage products. Then we add systematic price variation for foods to simulate five taxes and subsidies: a fruit and vegetable subsidy and taxes on sugar, saturated fat, salt, and sugar-sweetened beverages.

Using an experimental design, 1000 adult New Zealand shoppers complete five household grocery shops in the Virtual Supermarket where they are randomly assigned to one of the 5000 price sets each time.

Output data (i.e., multiple observations of price configurations and purchased amounts) are used as inputs to econometric models (using Bayesian methods) to estimate accurate PE values.

A disease simulation model will be run with the new PE values as inputs to estimate QALYs gained and health costs saved for the five policy interventions.

Discussion

The Price ExaM study has the potential to enhance public health and economic disciplines by introducing internationally novel scientific methods to estimate accurate and precise food PE values. These values will be used to model the potential health and disease impacts of various food pricing policy options. Findings will inform policy on health-related food taxes and subsidies.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12616000122459 (registered 3 February 2016).

Impact of sugars and sugar taxation on body weight control: A comprehensive literature review

OBJECTIVE

To conduct a comprehensive literature review in the field of added-sugar consumption on weight gain including the effect of fructose-containing caloric sweeteners and sugar taxation.

METHODS

A search of three databases was conducted in the time period from the inception of the databases to August 2015. Sensitive search strategies were used in order to retrieve systematic reviews (SR) of fructose, sucrose, or sugar-sweetened beverages (SSBs) on weight gain and metabolic adverse effects, conducted on humans and written in English, Spanish, or French. In addition, a review about SSB taxation and weight outcomes was conducted.

RESULTS

The search yielded 24 SRs about SSBs and obesity, 23 SRs on fructose or SSBs and metabolic adverse effects, and 24 studies about SSB taxation and weight control.

CONCLUSIONS

The majority of SRs, especially the most recent ones, with the highest quality and without any disclosed conflict of interest, suggested that the consumption of SSBs is a risk factor for obesity. The effect of fructose-containing caloric sweeteners, on weight gain is mediated by overconsumption of beverages with these sweeteners, leading to an extra provision of energy intake. The tax tool alone on added sugars appears insufficient to curb the obesity epidemic, but it needs to be included in a multicomponent structural strategy.

Effects of nutrient profiling and price changes based on NuVal® scores on food purchasing in an online experimental supermarket

OBJECTIVE

The goal of the present study was to apply experimental economic methods in an online supermarket to examine the effects of nutrient profiling, and differential pricing based on the nutrient profile, on the overall diet quality, energy and macronutrients of the foods purchased, and diet cost.

DESIGN

Participants were provided nutrient profiling scores or price adjustments based on nutrient profile scores while completing a hypothetical grocery shopping task. Prices of foods in the top 20 % of nutrient profiling scores were reduced (subsidized) by 25 % while those in the bottom 20 % of scores were increased (taxed) by 25 %. We evaluated the independent and interactive effects of nutrient profiling or price adjustments on overall diet quality of foods purchased as assessed by the NuVal® score, energy and macronutrients purchased and diet cost in a 2×2 factorial design.

SETTING

A large (>10 000 food items) online experimental supermarket in the USA.

SUBJECTS

Seven hundred and eighty-one women.

RESULTS

Providing nutrient profiling scores improved overall diet quality of foods purchased. Price changes were associated with an increase in protein purchased, an increase in energy cost, and reduced carbohydrate and protein costs. Price changes and nutrient profiling combined were associated with no unique benefits beyond price changes or nutrient profiling alone.

CONCLUSIONS

Providing nutrient profile score increased overall NuVal® score without a reduction in energy purchased. Combining nutrient profiling and price changes did not show an overall benefit to diet quality and may be less useful than nutrient profiling alone to consumers who want to increase overall diet quality of foods purchased.

Experimental analysis of the effect of taxes and subsides on calories purchased in an on-line supermarket

Taxes and subsidies are a public health approach to improving nutrient quality of food purchases. While taxes or subsidies influence purchasing, it is unclear whether they influence total energy or overall diet quality of foods purchased. Using a within subjects design, selected low nutrient dense foods (e.g. sweetened beverages, candy, salty snacks) were taxed, and fruits and vegetables and bottled water were subsidized by 12.5% or 25% in comparison to a usual price condition for 199 female shoppers in an experimental store. Results showed taxes reduced calories purchased of taxed foods (coefficient = -6.61, CI = -11.94 to -1.28) and subsidies increased calories purchased of subsidized foods (coefficient = 13.74, CI = 8.51 to 18.97). However, no overall effect was observed on total calories purchased. Both taxes and subsidies were associated with a reduction in calories purchased for grains (taxes: coefficient = -6.58, CI = -11.91 to -1.24, subsidies: coefficient = -12.86, CI = -18.08 to -7.63) and subsidies were associated with a reduction in calories purchased for miscellaneous foods (coefficient = -7.40, CI = -12.62 to -2.17) (mostly fats, oils and sugars). Subsidies improved the nutrient quality of foods purchased (coefficient = 0.14, CI = 0.07 to 0.21). These results suggest that taxes and subsidies can influence energy purchased for products taxed or subsidized, but not total energy purchased. However, the improvement in nutrient quality with subsidies indicates that pricing can shift nutritional quality of foods purchased. Research is needed to evaluate if differential pricing strategies based on nutrient quality are associated with reduction in calories and improvement in nutrient quality of foods purchased.

Is Sugar the new Tobacco? Insights from Laboratory Studies, Consumer Surveys and Public Health

In the Americas, mean energy intake from added sugar exceeds recent World Health Organization recommendations for free sugars in the diet. As a leading contributor to this excess, sugar-sweetened beverage (SSB) overconsumption represents a risk for the population's health. This article provides an overview of clinical and epidemiological evidence, marketing practices, corporate influence and prevention strategies related to added sugar and SSB. For each aspect of this multidimensional profile, we briefly compare SSB to the case of tobacco pointing to similarities but also major differences. Tobacco control has demonstrated the effectiveness of long term multifaceted prevention strategies in multiple settings supported by strong public policies which may be applied to the consumption of SSB. However, translating these policies to the specific case of SSB is urgently needed, to inform preventive actions, decide which intervention mix will be used, and evaluate the process and impact of the chosen strategy.

Food environment and obesity

OBJECTIVE

The food environment plays an important and often dominant role in food choice, eating patterns, and ultimately, energy intake. The Obesity Society and the American Society for Nutrition jointly sponsored a series of reviews on topics of interest to both memberships. The goal was to consider the state of understanding on selected issues related to the food environment and obesity and to identify key knowledge gaps.

RESULTS

The first article (not necessarily of importance) targeted energy density (ED) and focuses on the role of ED in the regulation of energy intake and body weight. It offers recommendations for prioritizing research. The second article addresses economic factors and examines food and beverage purchases as a function of price changes. It concludes that targeted food taxes and subsidies alone are unlikely to substantially affect obesity. The third article concerns sweetened beverages and points out the difficulty in establishing the strength of the association between intake of sugar-sweetened beverages and weight gain and obesity. In the fourth article, the contributions of palatability and variety to eating behavior and weight are reviewed. Article five explores the influence of portion size on energy intake and weight management. It finds that consumers generally tend to eat proportionally more as portion size increases. The sixth article focuses on the efficacy and effectiveness of eating frequency manipulations for body weight management and finds that such manipulations have consistently yielded null results. Finally, article seven identifies several limitations of the existing literature regarding neighborhood access to healthy foods.

CONCLUSIONS

This series of reviews addresses important questions regarding the contribution of the food environment to obesity. Independent of physiological/genetic determinants, factors such as ED, cost, food form, palatability, variety, portion size, eating frequency, and access to healthy food are each evaluated for their role in the etiology of obesity and metabolic health. This series of reviews also identifies important gaps in knowledge.

Research issues: the food environment and obesity

"Research Issues: The Food Environment and Obesity" is an article series commissioned by the American Society for Nutrition and The Obesity Society in an attempt to consider the state of understanding on this topic and identify key knowledge gaps. Roberts and Karl focus on the role of energy density in the regulation of energy intake and body weight and offer recommendations for prioritizing research. Finkelstein et al examine food and beverage purchases as a function of price changes and conclude that targeted food taxes and subsidies alone are unlikely to substantially affect obesity. Pereira points out the difficulty in establishing the strength of the association between intake of sugar-sweetened beverages and weight gain and obesity. Johnson and Wardle review the effects of palatability and variety on eating behavior and weight. Livingstone and Pourshahidi examine the impact of portion size manipulations on energy intake and weight management and find that consumers generally tend to eat proportionally more as portion size increases. Kant focuses on the efficacy and effectiveness of eating frequency manipulation for body weight management and finds that such manipulation has consistently yielded null results. Finally, Gordon-Larsen identifies several limitations of the existing literature regarding neighborhood access to healthy foods.