Effects Of Early Life Environmental Unpredictability On Overeating

Overeating refers to energy intake that is disproportionately larger than energy expenditure.Chronic overeating is directly related to overweight,obesity,and problems such as depression,anxiety,self-injury and substance use.Life history theory posits that high early life environmental unpredictability(ELEU),such as punitive or inconsistent caregiving,frequent residential changes,lower socioeconomic status(SES),inadequate resources and social networks that include dangerous or unstable persons,represent threats,and material as well as emotional resources that are not enough to satisfy necessary needs.Such experiences cause children to develop relatively faster life history strategies — cognitive and behavioral tendencies that maximize current gratification despite potentially negative future consequences — that invest more time and effort in activities having immediate payoffs because the future is uncertain and delayed rewards or benefits may be unavailable later.Individuals with fast life history strategies have relatively shorter lifespan,reach sexual maturity earlier,have more offspring.Food,especially highly palatable food,has immediately rewarding properties that satisfy basic energy needs in addition to providing distraction from negative events.Thus individuals who process fast live history strategies would tend to overeating in front of food,suggesting that living in harsh,unstable circumstances,including inconsistent caregiving,frequent residential changes,lower socioeconomic status(SES),contribute to overeating and increased risk for obesity.However,there is a lack of studies that describes the current situation,developmental trajectory and demographic difference of overeating among Chinese population.Another limitation of studies based on life history theory has been retrospective studies within western cultures and did not recruit adolescents that are in their early stages to explore the links of ELEU and use of fast LHstrategies with overeating.Furthermore,possible behavioral and neural mechanism between these associations have never been tested using longitudinal design.Finally,previous overeating intervention has been limited to offline context,narrowing the intervention extension.After the outbreak of the COVID-19,face-to-face intervention increased the risk of virus spreading.It is necessary to explore online intervention method.The present study sought to investigate the prevalence of overeating,examining whether ELES affects overeating as well as the underlying behavioral and neural mechanism and investigating the effects of online overeating intervention through experimental design,longitudinal survey,and resting state f MRI method.Study 1 aimed at exploring the demographic features and the developmental trajectories of overeating.The study recruited 1,513 early adolescents aged from 11 to14.Participants were asked to fill the overeating scale at in September 2017(time 1),six months later in April 2018(time 2),thirteen months later in October 2018(time 3),and twenty months later in May 2019(time 4).Results indicated that girls scored higher than boys on overeating and the overeating scores were positively associated with age.Findings suggested that girls bear higher obesity risks.Future prevention interventions should focus more on girls and early adolescents.Study 2 aimed at investigating whether ELEU affects overeating.The study recruited 91 early adolescents aged from 12 to 14 and adopted the eating in the absence of hunger protocol.Participants were randomly allocated to two groups.Forty-three of them were assigned to the satiety condition and the other forty-eight of them were assigned to the hunger condition.After the experimental manipulation,all participants completed the food portion choice task and actual energy intake measures.Manipulation check showed that two groups did not differ at baseline hunger measure,while participants in hunger group reported significantly higher hunger scores than those in satiety group,suggesting the manipulation is valid.Further,moderation analyses showed that hunger state could moderate the association between ELEU and high-calorie as well as low-calorie food portion,but can not moderate the association between ELEU and actual food consumption or actual calorie consumption.Simpleanalyses indicated that,(a)in absence of hunger state,participants living in high environmental unpredictability selected more high-calorie/unhealthy food portion than those living in low environmental unpredictability,i.e.,overeating,while in hunger state environmental unpredictability was not associated with selected high-calorie/unhealthy food portion;(b)in absence of hunger state,environmental unpredictability was not associated with selected low-calorie/healthy food portion,while in hunger state,participants living in high environmental unpredictability selected less low-calorie/healthy food portion than those living in low environmental unpredictability.Hence,our results,on the one hand,supported the initial hypothesis that early life environmental unpredictability could promote overeating in the absence of hunger state.On the other hand,our findings demonstrated that individuals in the hunger state would be more impulsive,selecting less healthy food.Meanwhile,the study contributes to the prevention and intervention of overeating.The nurturers could try to improve the environmental stability(e.g.,act in consistency)in reducing overeating.Study 3 aimed at revealing the behavioral mechanism of how ELEU affects overeating.The study recruited 1513 early adolescents to complete ELEU scale,fast life history strategies scale(mini-k),and overeating scale at baseline in September 2017,six months later in April 2018,thirteen months later in October 2018,and twenty months later in May 2019.Structural equation modeling analyses indicated that baseline ELEU could affect overeating 20 months later through fast life history strategies for girls but not for boys.Life history theory tenets that children who experience ELEU are prone to adopting faster LH strategies characterized by a quest for immediate gratification of current needs instead of pursuits having long-term benefits.In general,overeating facilitates fat storage and protects against potential food scarcity as a result of ELEU.That is,if the future availability of food is uncertain,then eating as much as possible while one has access to food is adaptive,at least in the short-run.However,for girls,in particular,storing fat facilitates sexual maturation.Hence,early adolescent girls who experiences more ELEU may have stronger orientations toward fast life history strategies reflecting the prioritization of more immediate rewards and reproductioncapacities.Findings suggested that overeating intervention should focus more on girls to reduce the possible physical and psychological outcomes.Educators could guide children to shift their fast life history strategies tendency,and focus on long-term benefits and healthy behaviors in reducing overeating.Study 4 aimed at examining the underlying neural basis of how ELEU affects overeating.The study recruited 440 late adolescents aged from 16 to 22 to complete the resting state functional magnetic resonance imaging scan.Participants also filled the retrospective measures of ELEU scale(recall of ELEU at their early age),death threat scale,social support scale and overeating scale at six months follow-up,and participants also completed the death threat scale and overeating scale at eight months follow-up.Results revealed that retrospective reports of ELEU was negatively associated with inferior frontal gyrus(IFG)connectivity,and it was further correlated to overeating at six and right months follow-ups.IFG specializes in processing silent information and regulating behaviors.Decreased connectivity in this region may underlie deficits in behavioral control in adolescents.A possibility exists that ELEU may shape the IFG functions to become less able to regulate emotions or control behaviors and lead to subsequent overeating.It is suggested that in the adaption of ELEU,individuals may have evolved in their brain to be more impulsive and the changes further caused loss of control eating and overeating.Intervention program could develop cognitive training to improve the ability of emotional regulation and inhibitory control in order to reduce overeating.Study 5 aimed at exploring if death threat and social support moderated the IFG activity/connectivity and overeating.Results indicated that,when death threat was low,the mediation model was established;while when death threat was high,the mediation model cannot be established.In addition,when social support was low,the mediation model was established,however when social support was high,the mediation model cannot be established.Findings suggested that when death threat was low,the ability to control behaviors and regulate emotions were able to decrease overeating;while when death threat was high,all participants tend to maximize the current gratification to adaptthe extreme environment,causing loss of control and the inhibitory control ability was not able to regulate behaviors.Meanwhile,the effects of current environment on behaviors were larger than that of regulation ability,indicating the behavioral strategies has changed into overeat in response to extreme environment.It is also suggested that social support could buffer the effects of low inhibitory control on overeating and could act as an protective factor of overeating.Family,friends could try to provide social support and the policy makers could encourage a “supportive” atmosphere in order to reduce overeating.Based on the evidence that social support could act as a buffer of overeating,study6 aimed at testing the effects of online supportive community overeating intervention based on cognitive dissonance theory.372 adolescents were randomly assigned to intervention group(n=191)and control group(n=181).The intervention group received intervention(for 35-45 minutes)based on cognitive dissonance theory in online supportive community once a week while the control group read the educational brochure for 35 minutes a week.The intervention lasts for 6 weeks for two groups.All participants completed baseline,6-week posttest and 6 months follow-up test regarding self-esteem,positive body image and overeating symptoms.Results indicated that,compared to brochure controls,participants in the intervention group reduced more in overeating symptoms,increased more in self-esteem from baseline to posttest.Moreover,compared to brochure controls,participants in the intervention group increased more in self-esteem symptoms and positive body image from baseline to follow-up.Results of this study suggested the e Body Project has utility in reducing overeating as well as promoting positive self-perceptions among young women in China.Women who took part in the e Body Project program experienced significantly greater baseline to posttreatment improvements on self-esteem and reduction in overeating than did women in an education brochure control condition.Reassuringly,the intervention difference of self-esteem and positive body image remained significant in pretreatment to 6-month follow-up comparisons,though effect sizes were attenuated over time.Due to its format and effectiveness,the e Body Project appears to have potential advantagesover moderated interventions in that it is suitable in China where resources for therapy and supervision are limited or unavailable altogether.The study described the current situation,revealed whether ELEU affected overeating as well as the underlying behavioral and neural mechanism,and made an intervention attempt to reduce overeating through five serial studies.Findings provided an evolutionary explanation for the prevalence and maintain of overeating,and extended life history theory into neural studies,and provide a neuro-evolutionary perspective in explaining impulsive actions such as substance use and risk taking.