Analysis of price changes and food purchases in obese and lean mothers

描述（由申请人提供）：我们最近发现，对不健康（营养高热量）食品征税减少了能量摄入和膳食脂肪的购买，增加了蛋白质的购买，而对健康食品（营养低热量）的补贴增加了购买的能量，但购买的大量营养素的分布没有变化。本应用程序的目的是研究收入、体重指数（BMI）、食物的相对强化值（RRV）和冲动性是否会调节价格对购买的能量和大量营养素以及饮食质量的影响，该影响涉及225名种族和经济状况不同的成年人。参与者将完成五次购物，与参考价格相比，所选休闲食品的税率为+12.5和+25%，水果和蔬菜和无糖水的补贴为-12.5%和-25%。具体目标1将评估价格变化对购买的能量和常量营养素的影响，预测税收将减少购买的能量和膳食脂肪，提高饮食质量，而补贴将增加水果和蔬菜以及购买的能量。具体目标2将评估收入对食品购买的调节作用，并预测低收入家庭对税收更敏感，与高收入家庭相比，当这些食品被征税时，他们购买的能量和脂肪的减少幅度更大，饮食质量的改善幅度更大。我们预测，低收入家庭对健康食品补贴的反应会更积极。具体目标3将评估BMI对食物购买的调节作用，并预测BMI较高的参与者对税收不太敏感，当这些食物被征税时，与BMI较低的参与者相比，他们购买的能量和脂肪减少较少，饮食质量改善更大。BMI指数较低的参与者对购买更多水果和蔬菜的补贴反应更积极。具体目标4将测试RRV作为食品购买的调节因素，并预测对较不健康食品的RRV较大的参与者对减少能量和脂肪购买和改善饮食质量的税收影响的反应较弱，相反，对较健康食品的RRV较大的参与者将显示出购买的能量和脂肪减少和改善饮食质量，因为水果和蔬菜和无糖水的补贴增加。具体目标5将评估冲动作为食物购买的调节因素，预测更冲动的参与者对减少能量和脂肪购买和改善饮食质量的税收影响的反应更弱，而那些发现食物增强和冲动的参与者在零食征税时，会显示出能量和脂肪购买的最小减少和饮食质量的改善。相反，当水果、蔬菜和无糖水的价格得到补贴时，那些不那么冲动的人更有可能增加水果、蔬菜或无糖水的购买量。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: 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.