Delay discounting and utility for money or weight loss

Temporal discounting as a candidate behavioral marker of obesity

Although obesity is a result of processes operating at multiple levels, most forms result from decision-making behavior. The aim of this review was to examine the candidacy of temporal discounting (TD) (i.e. the reduction in the value of a reinforcer as a function of the delay to its receipt) as a behavioral marker of obesity. For this purpose, we assessed whether TD has the ability to: identify risk for obesity development, diagnose obesity, track obesity progression, predict treatment prognosis/outcomes, and measure treatment effectiveness. Three databases (Pubmed, PsycINFO, and Web of Science) were searched using a combination of terms related to TD and obesity. A total of 153 papers were reviewed. Several areas show strong evidence of TD's predictive utility as a behavioral marker of obesity (e.g., distinguishing obese from non obese). However, other areas have limited and/or mixed evidence (e.g., predicting weight change). Given the positive relationship for TD in the majority of domains examined, further consideration for TD as a behavioral marker of obesity is warranted.

Randomized controlled trials of self-monitoring interventions with or without incentives for diet and exercise among individuals with overweight or obesity: Psychological and behavioural effects

OBJECTIVES

To test the effects of three behavioural interventions (daily monetary incentives + self-monitoring, delayed lump sum monetary incentives + self-monitoring, and self-monitoring only) on psychological constructs and fruit and vegetable consumption or physical activity behaviour change among a sample of adults with overweight or obesity.

DESIGN

A pair of 3-arm longitudinal randomized controlled trials compared daily monetary incentives + self-monitoring, delayed lump sum monetary incentives + self-monitoring, and self-monitoring only interventions for either fruit and vegetable consumption or physical activity.

METHODS

Individuals reporting elevated weight status and insufficient engagement in one of the target behaviours were randomly assigned to one of three 3-week interventions. All three interventions involved daily self-monitoring of the behaviour, and two provided monetary incentives contingent upon reported behaviour. Participants completed measures of psychological constructs and reported behaviour at baseline, the end of the intervention, and two and four weeks post-intervention.

RESULTS

Participants across all three intervention conditions demonstrated increased engagement in the target behaviour from pre- to post-intervention and reported behaviour remained above baseline levels at both follow-up time points. Increases in reported behaviour during the intervention were associated with increases in self-efficacy, and this enhanced self-efficacy prospectively predicted sustained reported behaviour at follow-up. However, contrary to hypotheses, the incentive interventions including self-monitoring were not more efficacious than self-monitoring alone, and increased reported behaviour was not associated with enhancements in attitudes.

CONCLUSIONS

Self-monitoring interventions can aid behaviour change efforts, and behavioural practice during these interventions can increase self-efficacy. However, among adults with overweight or obesity who are seeking behaviour change interventions, incentive-based self-monitoring approaches may not be superior to self-monitoring alone in driving behaviour change and maintenance.

A review of cross-commodity delay discounting research with relevance to addiction

Delay discounting (DD) refers to the decrease in the subjective value of a reward as the delay to its receipt increases. As high rates of DD are consistently associated with measures of substance misuse, DD is an important construct in current conceptualizations of addiction. High rates of DD appear to model preference for the immediate rewards provided by substance use, resulting in the interpretation that individuals with substance use disorder are generally unable or unwilling to delay gratification to obtain larger but delayed rewards. This interpretation is largely based on literature implementing binary choice tasks using differing amounts of the same commodity (i.e., single-commodity), in which high rates of DD can result from relative preference for the immediate outcome or relative dispreference for the delayed outcome. We propose that tasks using different commodities (i.e., cross-commodity) for the immediate and delayed outcomes offer potential in disentangling these dissociable and consequentially distinct interpretations. Our review suggests that cross-commodity DD tasks provide unique insights into understanding addiction not captured by single-commodity designs. We conclude that more research implementing cross-commodity DD tasks is needed to better understand the role of intertemporal choice in addiction and recovery.

Temporal discounting does not influence body mass index

The prevalence of obesity has driven searches for cognitive or behavioural economic factors related to Body Mass Index (BMI). One candidate is delay discounting: those who prefer smaller sooner rewards over larger but later rewards are hypothesised to have higher BMI. The findings in the literature are mixed however, with meta analyses suggesting only a very small correlation between discounting and BMI. Here we present novel empirical data (N=381) and Bayesian analyses which suggest no such relationship between discounting of either monetary or weight loss rewards and BMI. We also find evidence against our novel proposal that discounting moderates the rate of BMI gain over time. We also present our data in the context of a random effects Bayesian meta-analytical result which does suggest the presence of a small correlation overall. The strength of the correlation is so weak (2.25% shared variance) that its practical significance may be minor to non existent. However because we found decisive evidence for unaccounted for study-level variance, due to study heterogeneity, we argue that we should treat such meta-analytic correlations with extreme caution. While the relationship between discounting and health outcomes such as BMI remain theoretically appealing, our empirical and meta-analytic results suggest we should be cautious in inferring a correlational, let alone a causal, role for discounting processes in driving BMI or moderating BMI gain with age.

Accumulating Data to Optimally Predict Obesity Treatment (ADOPT) Core Measures: Psychosocial Domain

BACKGROUND

Within the Accumulating Data to Optimally Predict obesity Treatment (ADOPT) Core Measures Project, the psychosocial domain addresses how psychosocial processes underlie the influence of obesity treatment strategies on weight loss and weight maintenance. The subgroup for the psychosocial domain identified an initial list of high-priority constructs and measures that ranged from relatively stable characteristics about the person (cognitive function, personality) to dynamic characteristics that may change over time (motivation, affect).

OBJECTIVES

This paper describes (a) how the psychosocial domain fits into the broader model of weight loss and weight maintenance as conceptualized by ADOPT; (b) the guiding principles used to select constructs and measures for recommendation; (c) the high-priority constructs recommended for inclusion; (d) domain-specific issues for advancing the science; and (e) recommendations for future research.

SIGNIFICANCE

The inclusion of similar measures across trials will help to better identify how psychosocial factors mediate and moderate the weight loss and weight maintenance process, facilitate research into dynamic interactions with factors in the other ADOPT domains, and ultimately improve the design and delivery of effective interventions.

Delay discounting and utility for money or weight loss

Objective

Obesity is related to a bias towards smaller immediate over larger delayed rewards. This bias is typically examined by studying single commodity discounting. However, weight loss often involves choices among multiple commodities. To our knowledge, no research has examined delay discounting of delayed weight loss compared with other commodities.

Methods

We examined single commodity discounting of money and cross commodity discounting of money and weight loss in a sample of 84 adults with obesity or overweight statuses interested in weight loss. The exchange rate between money and weight loss was calculated, and participants completed two delay discounting tasks: money now versus money later and money now versus weight loss later.

Results

Participants discounted weight loss more than money (p < 0.001). When participants were divided into those who preferred weight loss (n = 61) versus money (n = 23), those who preferred money over weight loss discounted weight loss even more than individuals that preferred weight loss (p = 0.003).

Conclusions

Greater discounting of weight loss for those who preferred money suggest that idiosyncratic preferences are related to multiple commodity discounting, and greater discounting of weight loss across all participants provide insight on important challenges for weight control.