生命早期环境不可预测性对过度进食的影响:基于生命史理论

Early life environmental unpredictability and overeating:Based on life history theory

在生命史理论的视角下,本研究通过两个研究揭示了生命早期环境不可预测性对过度进食的影响及其作用机制。研究1招募处于生命早期阶段的91名初中生(年龄12~14岁),采用饱食进食(Eating in the absence of hunger,EAH)范式,结果发现生命早期环境不可预测性能够显著正向预测个体饱食状态下的高热量食物选择(即过度进食);研究2招募新冠病毒疾病(COVID-19)爆发背景下301名武汉市居民(高死亡威胁组)和179名其他省市居民(控制组)(年龄18~60岁)为被试,通过问卷法回溯性地测量生命早期环境不可预测性并探究其影响当前过度进食的机制,结果发现生命早期环境不可预测性通过生命史策略的中介作用间接影响过度进食。同时,死亡威胁(新冠病毒疫情)扩大了环境不可预测性通过生命史策略间接影响过度进食的效应,而社会支持则能缓冲这一效应。研究结果为COVID-19背景下和灾后居民的健康进食干预提供了依据。

According to life history theory,organisms face necessary trade-offs in allocating limited energy and resources between somatic effort and reproductive effort.How an individual allocates resources to cope with survival and reproductive tasks reflects their life history strategies.In unpredictable environments,individuals tend to invest more in reproductive efforts and prioritize immediate payoffs because the future is uncertain,and the delayed benefits may not be available later.Food may be considered an immediate reward and overeating may more likely occur among people living in unpredictable environments.Our research investigated how early life environmental unpredictability affects overeating and the underlying mechanism between the association.Study 1 recruited 91 adolescent participants and utilized the Eating in the Absence of Hunger protocol(EAH).Participants were randomly assigned either to the"hunger"or"absence of hunger"groups.Both groups completed a food portion choice task.Participants were presented with photographs of 36 food types(18 high-calorie and 18 low-calorie),where participants chose their desired food portion on each picture from 0(none)to 4(four portions).Results indicated that the hunger state could moderate the effects of early life environmental unpredictability on overeating.Specifically,(a)in hunger state,environmental unpredictability was not associated with selected high-calorie/unhealthy food portion,while participants living in high environmental unpredictability selected more high-calorie/unhealthy food portion than those living in low environmental unpredictability,i.e.,overeating;(b)in hunger state,participants living in high environmental unpredictability selected less low-calorie/healthy food portion than those living in low environmental unpredictability,while in the absence of hunger state,environmental unpredictability was not associated with selected low-calorie/healthy food portion.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.Study 2 examined differences in overeating between participants with high and low perceived death threat states.The former group was comprised of 301 community residents from Wuhan City,the epicenter of the Coronavirus Disease 2019(COVID-19)outbreak.The latter group was comprised of 179 community residents from the 42 other cities in China.Participants completed questionnaires regarding early life environmental unpredictability,fast life history strategy(Mini-K),overeating,perceived death threat,and social support.Results indicated that early life environmental unpredictability may affect overeating through the mediating role of fast life history strategies.Moreover,perceived death threat and social support may moderate the path between fast life history strategies and overeating.Evidently,participants with both high and low death threats,fast life history strategies were positively associated with overeating;however,the effect was smaller for the latter grouping.For individuals with high social support,fast life history strategies were not associated with overeating;while for individuals with low social support,fast life history strategies were positively associated with overeating.Findings indicated that environmental unpredictability in early life was positively associated with overeating through fast life history strategies.Additionally,this effect intensifies when the current environment is life-threatening;while the effect would be buffered for individuals with high social support.Findings provided evidence for the prevention and intervention of healthy eating promotion in the context of COVID-19.