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There is limited research on how taxes and subsidies would influence the energy and nutritional quality of food purchases. Using an experimental analogue purchasing task, we examined the effects of increasing the price of high-calorie-for-nutrient foods or reducing the price of low-calorie-for-nutrient foods by 12.5% and 25% on mothers' purchases of 68 common foods and drinks. Taxing less healthy foods with low nutrient density reduced energy (caloric) intake, while reducing the proportion of fat and increasing the proportion of protein purchased. Subsidizing more healthful foods with high nutrient density increased energy intake, without changing the macronutrient profile of foods purchased. These results favor taxes as a way to reduce caloric intake.

Recent theoretical approaches to food intake hypothesize that eating represents a balance between reward-driven motivation to eat versus inhibitory executive function processes, however this hypothesis remains to be tested. The objective of the current study was to test the hypothesis that the motivation to eat, operationalized by the relative reinforcing value (RRV) of food, and inhibitory processes, assessed by delay discounting (DD), interact to influence energy intake in an ad libitum eating task. Female subjects (n = 24) completed a DD of money procedure, RRV task, and an ad libitum eating task in counterbalanced sessions. RRV of food predicted total energy intake, however the effect of the RRV of food on energy intake was moderated by DD. Women higher in DD and RRV of food consumed greater total energy, whereas women higher in RRV of food but lower in DD consumed less total energy. Our findings support the hypothesis that reinforcing value and executive function mediated processes interactively influence food consumption.

These results show the relevance of considering price change as a way to influence food purchases of LED compared with HED foods and the possibility that individual differences may influence the own-price elasticity of HED foods and substitution of LED for HED foods.

Behavioral choice theory and laboratory choice paradigms can provide a framework to understand the reinforcing efficacy or reinforcing value of food. Reinforcing efficacy is measured in the laboratory by assessing how much effort one will engage in to gain access to food as the amount of work progressively increases. However, this method to establish demand curves as estimates of reinforcer efficacy is time consuming and limits the number of reinforcers that can be tested. The general aim of this study was to compare the reinforcing efficacy of snack foods using a behavioral task that requires subjects to respond to gain access to portions of food (LAB task) with a questionnaire version of a purchasing task designed to determine demand curves (QUES task) in nonobese and obese adults (n = 24). Results showed correlations between the maximal amount of money that individuals were willing to spend for food (QUES O max ) and the maximal amount of responses made on the highest reinforcement schedule completed (LAB O max ) (r = 0.45, p < 0.05), and between BMI and the LAB O max (r = 0.43, p < 0.05) and the QUES O max (r = 0.52, p < 0.05). The study suggests the questionnaire provides valid measures of reinforcing efficacy that can be used in place of or in conjunction with traditional laboratory paradigms to establish demand curves that describe the behavioral maintaining properties of food. Keywords Reinforcement; Eating; Behavioral economicsFood is a powerful reinforcer, and developing a better understanding of the motivation to eat may be important for the treatment or prevention of obesity (Epstein, Leddy, Temple, & Faith, 2007). We have shown in a series of studies that obese adults and children are more motivated to work for palatable, favorite foods than leaner peers (Saelens & Epstein, 1996; Temple, * Corresponding author. Department of Pediatrics, School of Medicine and Biomedical Sciences, University at Buffalo, Farber Hall, Room G56, 3435 Main Street, Building #26, Buffalo, New York 14214-3000, United States. Tel.: +1 716 829 3400; fax: +1 716 829 3993. Contributors: Dr. Epstein obtained funding for the study, and designed, analyzed and interpreted data, and supervised writing of the manuscript. Ms. Dearing assisted with the design, analysis, interpretation and writing of the manuscript, while Ms. Roba assisted in the data collection and writing of the manuscript. Conflict of interest:The authors have no conflict of interest. Dr. Epstein is a consultant to Kraft Foods. Publisher's Disclaimer:This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. Legerski, Giacomelli, Salvy, & Eps...