Increasing blood glucose level via breakfast meals is not connected with changes in delay discounting

Perceived food palatability, blood glucose level and future discounting: Lack of evidence for blood glucose level's impact on reward discounting

Some previous studies have shown that an increase in blood glucose level makes people more future oriented, however, results are inconsistent, other studies failing to replicate this effect. Here, we tested whether psychological factors (in this instance, perception of food pleasantness after consumption of more palatable or less palatable meal) can play a moderating role. We hypothesized that consuming more palatable food (perceived as rewarding) should cause blood glucose levels to affect future discounting, but that this should not occur for the consumption of less palatable food. A high-powered, independent groups experiment (N = 149, power β = .90) showed that, subsequent to performing an initial discounting task, the two groups consuming a meal (a control group consumed no meal) displayed a significant increase in blood glucose levels 10 minutes after meal consumption and just before repeating the discounting task. However, the increased blood glucose levels did not cause changes in delay discounting in either experimental group.

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.