We recently found taxing less healthy (high calorie for nutrient) foods reduced energy intake and dietary fat purchased, and increased protein purchased, while subsidizing healthier foods (low calorie for nutrient) increased energy purchased with no change in distribution of macronutrients purchased. The goal of this application is to study whether income, body mass index (BMI), relative reinforcing value of food (RRV) and impulsivity moderate the effects of prices on energy and macronutrients purchased and diet quality in a large sample of 225 ethnically and economically diverse adults. Participants will complete five shopping sessions that vary whether selected snack foods are taxed by +12.5 and +25%, or fruits and vegetables and non- sweetened water are subsidized by -12.5% and -25% in comparison to shopping at reference prices.
Specific Aim 1 will evaluate the effect of price changes on energy and macronutrients purchased, with the prediction that taxes will reduce energy and dietary fat purchased and improve diet quality, while subsidies will increase fruits and vegetables and energy purchased.
Specific Aim 2 will assess income as a moderator of food purchases, with the prediction that lower income families will be more sensitive to taxes, and show greater reduction in energy and fat purchased and greater improvement in diet quality when these foods are taxed than higher income families. We predict that lower income families will be more responsive to subsidies for healthier foods.
Specific Aim 3 will assess BMI as a moderator of food purchases, with the prediction that higher BMI participants will be less sensitive to taxes, and show less reduction in energy and fat purchased and greater improvement in diet quality when these foods are taxed than lower BMI participants. Lower BMI participants will be more responsive to subsidies in purchasing more fruits and vegetables.
Specific Aim 4 will test RRV as a moderator of food purchases with the prediction that participants with greater RRV for less healthy items will be less responsive to effects of taxes on reducing energy and fat purchasing and improving diet quality, and conversely, those who have greater RRV for healthier foods will show a reduction in energy and fat purchased and improvement in diet quality as subsidies for fruits and vegetables and non-sweetened water are increased.
Specific Aim 5 will assess impulsivity as a moderator of food purchases with the prediction that more impulsive participants will be less responsive to effects of taxes on reducing energy and fat purchasing and improving diet quality, and participants who find food reinforcing and are impulsive will show the smallest reductions in purchases of energy and fat and improvements in diet quality when snack foods are taxed. Conversely, those who are less impulsive will be more likely to show an increase in purchases of fruits and vegetables or non-sweetened water when the prices of fruits and vegetables and non-sweetened water are subsidized.
Project Narrative The proposed research will assess whether income, body mass index, the reinforcing value of food and behavioral impulsivity, moderate the influence of changing prices on energy intake, macronutrients purchased and diet quality. Examining the effects of individual difference factors that influence the effectiveness of price interventions to influence food purchasing will provide insight into public policy decisions that can use taxes or subsidies to influence population health.
|Epstein, Leonard H; Finkelstein, Eric; Raynor, Hollie et al. (2015) Experimental analysis of the effect of taxes and subsides on calories purchased in an on-line supermarket. Appetite 95:245-51|
|Epstein, Leonard H; Jankowiak, Noelle; Fletcher, Kelly D et al. (2014) Women who are motivated to eat and discount the future are more obese. Obesity (Silver Spring) 22:1394-9|
|Epstein, Leonard H; Jankowiak, Noelle; Nederkoorn, Chantal et al. (2012) Experimental research on the relation between food price changes and food-purchasing patterns: a targeted review. Am J Clin Nutr 95:789-809|