A behavioral economic analysis of changes in food-related and food-free reinforcement during weight loss treatment

Abstract

Objective: Behavioral economic theory predicts that reductions in consumption of highly valued commodities, such as drugs or palatable food items, are facilitated by increasing engagement in reinforcing substitutes. The current study prospectively examines changes in engagement in and enjoyment of food versus food-free activities during an 18-month behavioral weight loss intervention.

Method: Participants were 202 overweight/obese individuals who took part in an 18-month behavioral weight loss treatment and were randomly assigned to a traditional hypocaloric, low-fat diet condition or a traditional hypocaloric, low-fat diet plus a goal to limit variety in snack food consumption condition. At baseline and 6, 12, and 18 months, participants were weighed and completed a measure that assessed recent frequency of engagement in and enjoyment of a variety of both food and food-free activities.

Results: Growth models revealed a statistically significant decrease in the relative percentage of food-related reinforcement (vs. food-free) over time (reinforcement ratio, or RR), with the greatest reduction during the first 6 months of treatment. Food-related reinforcement decreased over time, and food-free reinforcement increased. Additionally, the RR change predicted change in body mass index (BMI) from 0 to 6 months and 0 to 18 months, such that greater changes in RR were associated with greater changes in BMI.

Conclusions: Findings suggest that behavioral weight loss treatment may promote a shift away from food-related reinforcement toward food-free reinforcement and that this change may predict BMI change. Future interventions may consider targeting increasing engagement in enjoyable food-free activities to help with long-term maintenance.

PsycINFO Database Record (c) 2014 APA, all rights reserved.

Figures

Figure 1

Change in Reinforcement Ratio from Baseline to 18 months Note. The Y-axis contains the average reinforcement ratio (RR) values. The RRs were computed with the following formula: average food-related cross product / average food-related plus average food-free cross product. RR values can range from 0 (no reinforcement related to food) to 1 (100% of reinforcement related to food) Error bars reflect one standard error of the mean.

Figure 2

Change in Food and Food-Free Reinforcement from Baseline to 18 months Note. The Y-axis contains the average food-related and food-free reinforcement values. Both frequency and enjoyment are rated on a 4 point scale [range=0 (zero times per week) to 4 (more than once per day)] and enjoyment ratings [range=0 (unpleasant or neutral) to 4 (extremely pleasant), respectively]. A cross-product, reflecting “obtained reinforcement” from each activity, was computed by multiplying the frequency and the enjoyment ratings (separately for food-related and food-free participation). The average of the food-related and food-free cross-product scores were computed to measure average food-related and food-free reinforcement for each individual. Error bars reflect one standard error of the mean.