Understanding the psychological basis of obesity

肥胖症的流行是我们这个时代最大的公共卫生危机之一，每年有超过3万人因肥胖而英年早逝。与正常体重的人相比，肥胖者的生活质量大幅下降，更有可能出现健康问题，死得更早。肥胖症传统上被认为是一种“有机”或生物学的疾病模型：肥胖症之所以持续存在，是因为体内平衡系统防止体重减轻，肥胖症患者英年早逝的原因可归因于体内脂肪过多的生物压力。然而，目前我们缺乏对肥胖症如此难以治疗的细微差别的理解，为什么有些人会发展成更严重的高风险肥胖症，以及为什么肥胖症与预期寿命减少有关。在这里，我们引入并测试了一个肥胖的“心理负担”模型，该模型提出，与较重体重相关的一系列心理因素对于理解肥胖的持久性(为什么减肥和保持体重如此困难)、进展(为什么有些人进展为严重的“高风险”肥胖)以及与肥胖相关的疾病负担(为什么肥胖预示着健康状况不佳和早期死亡)是关键。为了测试这一点，我们首先利用英国大型队列研究(千禧队列研究、国家儿童发展研究、英国队列研究)来量化心理因素在解释(I)一个人在一生中是否保持超重/肥胖与恢复到更健康的体重以及ii)严重肥胖的发展中所起的共同作用。我们通过检查心理因素如何共同解释肥胖的跟踪和儿童和成年期间严重肥胖的发展来做到这一点。接下来，我们利用大规模流行病学研究(英国老龄化纵向研究、美国健康与退休研究)的数据来检验肥胖相关疾病负担(即身体健康生物标记物的下降、慢性健康状况的发展以及与肥胖相关的早期死亡)在多大程度上是由与体重较重相关的一系列心理因素的集体影响所解释的。这个项目超越了理解肥胖的传统方法，这些方法要么主要依赖生物学描述，要么孤立地研究有限数量的心理因素。通过了解与体重较重相关的心理因素对肥胖和肥胖相关疾病的集体影响，本项目有可能改变医疗和公共卫生界对肥胖的理解方式，并改进治疗方法，以减少肥胖和肥胖相关疾病负担。目前，英国在体重管理干预和服务方面缺乏心理支持，在国家政府肥胖战略中也缺乏对肥胖的心理基础的考虑。我们的项目将突出导致肥胖结果的心理因素，因此有可能为政策提供信息。我们还将能够确定在治疗工作中可能有针对性的心理因素。为了确保这项研究的设计和传播是为了在学术界之外产生长期的影响，我们正在与肥胖健康联盟(OHA)合作，这是一个由44个组织(包括健康慈善机构、医学会和运动团体)组成的联盟，通过制定和倡导循证政策建议并影响决策者和媒体来塑造英国的肥胖政策。OHA成员将为最终研究设计提供意见，以最大限度地发挥可能的影响，并支持我们确保在适当的情况下，将我们的研究结果传播和传达给关键的利益相关者和政策制定者(例如，英国政府卫生和社会保障部、国家健康和护理卓越研究所)。

The obesity epidemic is one of the largest public health crises of our time and every year more than 30,000 die young because of obesity. Compared to people with normal weight, people living with obesity experience a dramatically reduced quality of life, are far more likely to develop ill health and die younger. Obesity has been traditionally characterised using an 'organic' or biological model of disease: obesity is persistent because homeostatic systems defend against weight loss and the reason people with obesity die young is attributable to the biological strain of excess body fat. However, at present we lack a nuanced understanding of why obesity is so difficult to treat, why some people go on to develop more severe 'high risk' obesity and why obesity is associated with reduced life expectancy. Here we introduce and test a 'psychological burden' model of obesity, which proposes that the range of psychological factors associated with heavier body weight collectively are key to understanding obesity's persistence (why it is so difficult to lose weight and keep it off), progression (why some people progress to severe 'high risk' obesity) and the obesity-related disease burden (why obesity is predictive of ill health and early mortality). To test this, we first make use of large UK cohort studies (Millenium Cohort Study, National Child Development Study, British Cohort Study) to quantify the role that psychological factors collectively have in explaining (i) whether a person remains overweight/obese vs. returns to a healthier weight over the life course and ii) the development of severe obesity. We do so by examining how psychological factors collectively explain the tracking of obesity and the development of severe obesity across childhood and adulthood. Next, we exploit data from large-scale epidemiological studies (English Longitudinal Study of Ageing, US Health and Retirement Study) to examine how much of the obesity-related disease burden (i.e. declines in biomarkers of physical health, development of chronic health conditions and early mortality associated with obesity) is explained by the collective effect of the range of psychological factors associated with heavier body weight. This project moves beyond traditional approaches to understanding obesity that have either relied largely on biological accounts or studied a limited number of psychological factors in isolation. By understanding the collective effect that the psychological factors associated with heavier body weight have on obesity and obesity-related ill health, the present project has potential to change the way that the medical and public health community understand obesity and improve treatment approaches to reduce obesity and the obesity-related disease burden. There is currently a lack of psychological support in weight management interventions and services in the UK and a lack of consideration of the psychological basis of obesity in national government obesity strategy. Our project will highlight the psychological factors contributing to obesity outcomes and therefore has potential to inform policy. We will also be able to identify psychological factors that could be targeted in treatment efforts. To ensure this research is designed and disseminated in order to achieve long lasting impact outside of academia, we are partnering with the Obesity Health Alliance (OHA); a coalition of 44 organisations (including health charities, medical societies and campaign groups) that shape UK obesity policy by developing and advocating for evidence-based policy recommendations and influencing decision makers and the media. OHA members will provide input into final study designs to maximise likely impact and support us in ensuring that our findings are disseminated and communicated to key stakeholders and policy makers (e.g. UK Government Department of Health and Social Care, National Institute for Health and Care Excellence), where appropriate.