Obesity and non-communicable disease in Malaysia: an imaging study of 6000 adults in the Malaysian Cohort Study

过多的体脂是世界范围内糖尿病、心脏病发作和中风的主要原因。身体质量指数(BMI；定义为体重(公斤)除以身高(米)的平方)是世界卫生组织定义超重和肥胖的基础，BMI在25到30公斤/平方米之间被归类为超重，超过30公斤/平方米被归类为肥胖。然而，越来越多的证据表明，特定BMI的体脂水平可能会因人群而异，这引发了对普遍适用的基于BMI的超重和肥胖指南的质疑。虽然体重指数在马来西亚经常被用来评估多余的身体脂肪，但还没有直接测量身体脂肪及其分布的大规模成像研究，这将使我们更好地了解身体组成和疾病结果之间的关系。从2006年到2012年，由马来西亚政府发起的马来西亚队列研究招募了106527名年龄在35岁及以上的成年人。参与者完成了一份生活方式问卷，接受了身体测量，提供了血液样本，现在正在跟踪健康活动。在6000名马来西亚队列参与者中，我们将使用英国生物库(由牛津大学纳菲尔德人口健康系协调的大型队列研究)建立的方案进行全身双能X射线吸收(DXA)成像(除提供身体脂肪百分比外，还提供身体脂肪分布的数据)。通过使用DXA成像，这项研究将可靠地评估传统的身体成分估计方法(包括BMI、腰围和腰臀比)与从DXA测量得出的马来西亚人口的绝对区域脂肪质量之间的关系。然后，它将评估这些措施与糖尿病和心血管疾病风险之间的关系，为公共卫生指南提供信息，说明这些人群中过量体脂的适当衡量标准，这些措施的理想“正常”范围，以及是否应该为马来西亚不同的种族群体提供不同的指南。DXA成像还将显著增强马来西亚队列研究肥胖的遗传和环境决定因素，以及肥胖导致糖尿病和心血管疾病的生物途径的潜力。并不是所有超重或肥胖的人都会因超重而遭受不良后果，部分原因是脂肪分布的差异。事实上，正如马来西亚队列最近报道的那样，马来西亚主要民族(马来人、印度人和中国人)的肥胖症(基于BMI)和2型糖尿病的患病率差异很大，BMI只能部分解释这一点。因此，更好地了解基于组织和器官特定脂肪储存库的种族间风险，将能够更准确地将有限的资源对准那些将获得最大利益的人。

Excess body fat is a major cause of diabetes, heart attacks and strokes, worldwide. Body-mass index (BMI; defined as weight in kilograms divided by height in meters squared) is the basis of the World Health Organisation's definition of overweight and obesity, with a BMI of between 25 and 30 kg/m2 classified as overweight, and over 30 kg/m2 as obese. However, there is increasing evidence that levels of body fat for a given BMI may vary between populations, raising questions regarding universally applied BMI-based guidelines for overweight and obesity. Although BMI is frequently used in Malaysia to assess excess body fat, there have been no large-scale imaging studies with direct measurements of body fat and its distribution which would allow us to understand better the relationship between body composition and disease outcomes in this population. From 2006-2012, The Malaysia Cohort study - initiated by the Malaysian government - recruited 106,527 adults aged 35 years or over. Participants completed a lifestyle questionnaire, underwent physical measurements, provided a blood sample and are now being followed for health events. In 6000 of The Malaysia Cohort participants, we will conduct whole-body Dual-energy X-ray Absorptiometry (DXA) imaging (which provides data on body fat distribution in addition to body fat percentage) using protocols established by the UK Biobank (a large cohort study co-ordinated by the Nuffield Department of Population Health, University of Oxford). This imaging sub-study will significantly enhance this national biomedical resource.Using DXA imaging, this study will reliably assess the relationship between conventional measures for estimating body composition (including BMI, waist circumference and waist-hip ratio) with the absolute regional fat masses derived from the DXA measurements in the Malaysian population. It will then assess the relationship between these measures and risk of diabetes and cardiovascular disease, to inform public health guidance on the appropriate measure of excess body fat in this population, the ideal 'normal' range of these measures, and whether guidance should vary for the different ethnic groups in Malaysia. DXA imaging will also significantly enhance the potential of The Malaysia Cohort to investigate the genetic and environmental determinants of obesity in Malaysia, and the biological pathways through which it causes diabetes and cardiovascular disease.Not all people who are overweight or obese suffer adverse consequence from their excess weight, in part due to differences in fat distribution. Indeed, as recently reported from The Malaysia Cohort, the prevalence of obesity (based on BMI) and type 2 diabetes is very divergent between the major ethnic groups in Malaysia (Malay, Indian and Chinese) and this is only partly explained by BMI. Therefore, a better understanding of the between-ethnic group risk, based on tissue and organ-specific fat depots, will enable more precise targeting of limited resources to those who will gain the most benefit.