Effects Of Ego Depletion On Food Choices In Restrained Eaters And The Neural Mechanisms: Inhibition Of Conflict Monitoring Ability Of Brain

In the present society,restrained eating,as a weight loss method adopted by more and more women,has been proven by a large number of studies that it is not an effective strategy.In real life,in order to achieve dieting,restrained eaters often consciously suppress their desire and thought for delicious food.However,researchers have found that this suppression of the idea of delicious food makes them more difficult to control in subsequent eating behaviors.From the viewpoint of limited resources,this suppression of the idea of delicious food will consume people's self-regulation resources and cause ego depletion.Studies have shown that ego depletion can lead to control failures in subsequent activities involving self-control,such as excessive smoking and drinking after ego depletion(Leeman,O' Malley,White,& Mckee,2010),unreasonable economic behavior(Wan,Rucker,Tormala,& Clarkson,2010),and risky behaviors(Fischer,Kastenmüller,& Asal,2012),etc.In the field of restrained eating,current research has focused on finding that ego depletion can cause restrained eaters to overeat and reduce their ability to inhibit control in subsequent eating behaviors(Vohs & Heatherton,2002;Zhou,Gao,Chen,& Kong,2017).However,in addition to "how much to eat","what to eat" is also a key factor affecting the success of dieting for restrained eaters.As a weight-concerned group,choosing between healthy and unhealthy food is a typical self-control dilemma they face.It is about whether they can successfully control their weight.Under the Paradoxical contradiction between the "weight control goal" and the "food hedonistic goal",in order to achieve the purpose of weight control,they must exert self-control to solve this dilemma.Therefore,it is of great interest to focus on whether restrained eaters under ego depletion conditions could successfully exercise controlin food choices.This study has some new ideas.First,this study adopted a more ecologically valid method of ego depletion for the first time to simulate the real situation faced by restrained eaters in real life,providing a more credible support for the study of ego depletion in theoretical and practical respect.Second,in the field of diet,the research on ego depletion is relatively single,and there is no study exploring the effect of ego depletion on the food choice in restrained eaters.This study used choices of healthy or unhealthy food as a measure of self-control and explored the effect of ego depletion on food choices for restrained eaters.Third,previous studies of ego depletion mostly used behavioral and electrophysiological methods,and there was relatively little evidence on brain imaging.In order to further reveal the reasons for self-control failure after ego depletion,this study used functional magnetic resonance imaging(fMRI)to explore its neural mechanism.According to the process model of depletion,ego depletion will weaken people's ability to monitor conflicts,resulting in subsequent self-control failure.Based on this model,this study focused on the brain area of conflict monitoring(dorsal anterior cingulate gyrus),and explored changes in activity levels of this region in restrained eaters after ego depletion.Fourth,this study also used a longitudinal tracking method to collect BMI changes of subjects after six months.The relationship between the brain activity of dorsal anterior cingulate gyrus when choosing food and changes of BMI during six months was analyzed and compared under two conditions.In a theoretical sense,the research questions in this study help clarify why restrained eaters' strategies to suppress food thoughts and cravings in real life are not conducive to weight control,and provide theoretical support for why restrained eating do not work well as an effective weight loss strategy.In a practical sense,it can help guide people who care about weight to avoid incorrect diet control strategies and scientifically control weight and diet.Study 1 used behavioral experiments to investigate the effects of ego depletion on food choices in restrained eaters.After questionnaire test on 784 female college students,we screened 92 restrained eaters who met the conditions,and divided them into depletion group(N = 42)and non-depletion group(N = 50).A food selection task paradigm was adopted to compare the proportion of unhealthy food choices between the two groups.The results showed that after ego depletion,restrained eaters chose more unhealthy foods(F(1,92)= 5.98,p = 0.002),and their response time was significantly shortened during food selection(F(1,92)= 12.97,p = 0.001),indicating that they experienced relatively few conflicts in food choices and made decisions faster.In order to further explore the neural mechanism behind the failure of restrained eaters in food choice after ego depletion,,the second study further adopted functional MRI.The process model of ego depletion(Inzlicht & Schmeichel,2012)believes that ego depletion will weaken people's ability to monitor conflicts,resulting in subsequent self-control failure.Based on this model,the second study focused on brain regions involved in conflict monitoring(dorsal anterior cingulate gyrus),and explored the activity changes of this brain area of restrained eaters after ego depletion.We selected 59 restrained eaters from 342 female college students,and divided them into depletion group(N = 24)and non-depletion group(N = 35).The same food choice paradigm was used to compare the differences in brain activity between the two groups.The results showed that the activity of the dorsal anterior cingulate cortex,the brain region responsible for conflict monitoring,was reduced in the depletion group compared with those who did not consume a depletion(t=4.08,p<0.001).From the perspective of functional integration,the relationship between the brain region of conflict monitoring and other brain regions was explored.Physiological and psychological interaction analysis found that functional connectivity between the anterior cingulate cortex and the precuneus was increased in the depleted subjects.(t = 5.00,p<0.01).The results revealed that suppression of daily food ideas in restrained eaters might lead to a decline in their ability to monitor conflicts between current behaviors and goals,as well as greater attention to their internal feelings,such as hunger,desire to eat,etc.This can lead to unhealthy eating behaviors.Study 3 used a longitudinal study to track the change in body weight of the subjects(N = 53)after six months,and explored the relationship between activities of the dorsal anterior cingulate gyrus and the change of BMI in restrained eaters of study 2 under two conditions.The results showed that there was no significant correlation between the variables(p>0.05).This result does not validate our hypothesis,indicating that the activity of the dorsal anterior cingulate during the food selection process,whether in the depleted or non-depleted group,cannot predict subsequent changes in BMI.In all,the conclusions of this study are as follows:(1)After ego depletion,the selection proportion of unhealthy foods increased significantly when restrained eaters faced with healthy and unhealthy food simultaneously.(2)After ego depletion,the activity level of the dorsal anterior cingulate gyrus,a region responsible for conflict monitoring,was significantly reduced,and the functional connection between the dorsal anterior cingulate gyrus and the precuneus was significantly enhanced.(3)Regardless of the depletion group or non-depletion group,the activity intensity of the dorsal anterior cingulate during the food selection process cannot predict the BMI change after six months.