DIET, OBESITY AND WEIGHT CHANGE IN PREGNANCY

在过去的几十年里，肥胖在美国的流行率不断上升，随之而来的是对健康的长期不利影响的蔓延，造成了严重的公共卫生和经济后果。虽然遗传因素对肥胖的影响是公认的，但导致个体对普通肥胖易感性的遗传因素影响不大，在某些触发环境因素的存在下，这种影响可能会被大大放大。现在，大约三分之二的育龄妇女进入怀孕时体重指数偏高，大多数妇女的妊娠相关体重增加超过了医学研究所的指导方针，导致母婴围产期和慢性健康风险增加。育龄妇女肥胖率的增加反映在妊娠期糖尿病患病率的增加上，妊娠期糖尿病增加了孕产妇和儿童健康不良后果的风险。先前有限的干预研究表明，短期产妇饮食和妊娠期体重增加有适度改善，很少有证据表明长期坚持。这些和传统的依赖于现有健康行为范式的减肥干预措施的充分证明的不足表明，需要创新，以允许改变饮食行为决定因素的理论框架。神经科学基础研究的最新发现表明，大脑对美味食物的奖励反应是当前理论框架中缺失的一个关键因素。个体在“食物奖励反应”方面有所不同，这是指对食物和饮食对大脑奖励系统的影响的敏感性。同时，食物的“强化价值”也各不相同，强化价值指的是食物激活大脑奖励系统的程度。虽然某些食物会引起对食欲稳态调节敏感的规范的食物奖励反应，但假设“超美味”食物会引起大脑奖励系统异常明显的激活，可能会减弱这种敏感性，导致以摄入超出能量需求的食物为特征的享乐性、非稳态暴饮暴食。反复食用超美味的食物会加强大脑的食物奖励反应，最终导致神经系统的变化，类似于滥用药物所观察到的变化。然而，这一迅速扩大的工作尚未纳入以人口为基础的研究。迄今为止，关于食物奖励反应和食物强化价值的研究主要是在普通人群中的小样本中进行的。然而，到目前为止，还没有研究在孕妇中检查这些构造。虽然我们知道，大多数妇女的体重增加超过了建议的水平，而且许多妇女没有恢复到孕前的体重，但关于怀孕期间和怀孕后饮食摄入量和体重变化的个人决定因素的数据不足。了解食物奖励反应性和食物强化值与孕期和产后饮食摄入和体重变化的关系，可能有助于制定临床和公共卫生干预措施，促进这一人群的最佳饮食和体重。

The rising prevalence of obesity in the U.S. over the past several decades and the accompanying spread of adverse long-ranging health effects pose serious public health and economic consequences. While a genetic contribution to obesity is well-established, genetic factors underlying individual susceptibility to common obesity have modest effects, which can be amplified considerably in the presence of certain triggering environmental factors. Approximately two-thirds of women of reproductive age now enter pregnancy at a high body mass index, and the majority of women experience pregnancy-associated weight gains in excess of Institute of Medicine guidelines, leading to increased perinatal and chronic health risks for both mother and child. The increased prevalence of obesity among women of reproductive age is reflected in a concomitant increase in the prevalence of gestational diabetes (GDM), which confers additional increased risk of adverse maternal and child health outcomes. Limited previous intervention research has indicated modest improvement in short-term maternal diet and gestational weight gain, with little evidence of long-term adherence. The well-documented inadequacies of these and traditional weight-loss interventions relying on existing health behavior paradigms suggest the need for innovations that allow for a shift in the theoretical framework underlying the determinants of eating behavior. Recent findings from basic research in neuroscience suggest that the brain reward response to highly palatable foods is a critical element that is currently absent in current theoretical frameworks. Individuals vary with respect to their �food reward responsivity�, which refers to susceptibility to the effects of food and eating on the brain reward system. Simultaneously, foods vary with respect to their �reinforcement value�, which refers to the degree to which foods activate the brain reward system. Whereas certain foods elicit a normative food reward response that is sensitive to homeostatic regulation of appetite, it is hypothesized that �hyperpalatable� foods, which elicit exceptionally pronounced activation of the brain reward system, may blunt this sensitivity, leading to hedonic, non-homeostatic overeating characterized by food intake beyond energetic needs. Repeated consumption of hyperpalatable foods reinforces the brain food reward response and culminates in neurological changes similar to those observed with drugs of abuse. However, this rapidly-expanding body of work has not yet been incorporated into population-based research. Research to date on food reward responsivity and food reinforcement value has been conducted primarily in small samples in the general population. However, to date, no studies have examined these constructs among pregnant women. While it is known that most women gain more weight than recommended and many do not return to their pre-pregnancy weight, there is insufficient data on individual determinants of dietary intake and weight change during and after pregnancy. Understanding the association of food reward responsivity and food reinforcement value with dietary intake and weight change during pregnancy and postpartum may be informative for the development of clinical and public health interventions that promote optimal diet and weight in this population.