People with overweight and obesity consistently attempt to regulate their weight but typically fail to control their eating behaviors. Reward learning impairments have recently been utilized to explain the problem. According to dual-system theory, reward learning and performance depend on the balance between goal-directed and habitual behavioral control system. As the goal-directed control system need time to operate, time pressure was exploited to temporarily hinder the goal-directed control system and unmask latent habitual responses. In the present study, we evaluated the reward learning behaviors, particularly goal-directed and habitual responses, in individuals with overweight and obesity, and evaluated the effects of time pressure on the expression of habits. A total of sixty-eight overweight/obesity and lean undergraduates underwent four outcome-revaluation tasks in food or non-food context, and under no or high time pressure conditions. We found that compared to lean individuals, individuals with overweight/obesity showed more habitual responses toward both food and non-food reward under the high time pressure condition; however, there was no group difference in habitual responses under the no time pressure condition. These results indicate a deficit in the formation of goal-directed control or an overreliance on habits under time pressure among individuals with overweight and obesity. These results support the Habit Hypothesis for Overeating that overweight and obesity are related to habit-like eating behaviors, due to a maladaptive adjustment between the habit and the goal-directed behavioral control systems. As a result, further developments of habit-based interventions can benefit weight loss and long-term weight loss maintenance.

Background: Overweight people have been revealed to have poor cognitive flexibility. Cognitive flexibility reflects proactive and reactive control abilities. However, the impairment had not been explicitly positioned at the cognitive stage. Therefore, this study provides increased support for impairment of cognitive flexibility due to overweight. Method: The study included 34 overweight and 35 normal-weight participants. They were required to complete the food and flower target AX-continuous performance test (AX–CPT), including the resting-state fMRI and cue-triggered food craving subscales. We compared the performance difference between the two tasks. Furthermore, we investigated whether the cue-triggered food cravings and the corresponding brain regions mediated the effect of overweight on the two control mechanisms. Result: Significant differences were found only in the food target AX-CPT task, where overweight participants performed worse. Cue-triggered food cravings mediated this relationship. Additionally, we found that the brain regions associated with cue-triggered food cravings (bilateral SFG) can completely mediate the relationship between BMI and the z-value of the fat mass index and sensitivity to proactive control. Conclusion: In the food target task, overweight participants performed worse in both control mechanisms. Moreover, we also revealed the potential mechanism by which being overweight might affect the two control mechanisms through cue-triggered food cravings.

Objectives: This study aims to reveal the individual differences in Neuroticism and cognitive flexibility among successful restrained eaters (SREs), unsuccessful restrained eaters (UREs), and non-restrained eaters (NREs). Moreover, this study is dedicated to investigating whether certain personality traits and cognitive flexibility could concurrently influence disinhibited eating behaviors among restrained eaters and reveal the pathways through which they interact. Methods: Female participants aged 17 and 24 years (NREs = 23; SREs = 24; UREs = 23) were assessed with body mass index (BMI) and appetite state measurement, the Dutch Eating Behavior Questionnaire (DEBQ), the NEO Five-Factor Inventory (NEO-FFI), and the Positive and Negative Affect Schedule. To measure behavioral and neural responses related to cognitive flexibility, participants were required to complete a food-related switching task, and their brain activities were recorded through the technique of electroencephalography (EEG). Here we analyzed two widely investigated components-the N2 and P3 components that separately relate to conflict monitoring and response inhibition. Results: The behavioral performance of food-related task switching did not show significant between-group differences. However, in comparison to NREs and SREs, UREs elicited larger N2 and lower P3 amplitudes during task switching. In addition, UREs exhibited a lower level of Neuroticism than SREs and NREs. Furthermore, food-related task switching induced N2 amplitude fully mediated the association between Neuroticism and disinhibited eating behavior in restrained eaters controlled for BMI and negative affect. Importantly, when a parallel mediation model with N2 and P3 was built concurrently, N2 was still able to fully mediate the association. Conclusion: According to behavioral and neural evidence, increased N2 amplitude induced by food-related task switching totally mediated the negative association between Neuroticism and disinhibited eating in restrained eaters.