Wahlqvist Mark L, Chuang Shao-Yuan
Division of Preventive Medicine and Health Services Research, Institute of Population Health Sciences, National Health Research Institutes, No. 35 Keyan Road, Zhunan Town, Miaoli County, Taiwan 35053, ROC.
Asia Pac J Clin Nutr. 2012;21(4):471-5.
The body mass index (BMI) has served public health and clinical medicine well in the recognition of obesity. However, its use has generated some instructive paradoxes and misunderstandings which argue for the appreciation of body compositional disorders (BCD) as such and, in particular, for the parallel evaluation of muscle mass with a definition of 'orthosarcal' conditions to enable the early detection of sarcopenia. Across the life-span, and with gender and ethnic differentials, BCD is basic to the full spectrum of nutritionally-related disorders and diseases. In the case of metabolic diseases like diabetes, muscle, fatness and its distribution, and even bone seem to play pathogenetic roles. Optimal body fat and distribution are relevant to child development, maternal health and healthy ageing, with much more to learn about the mechanisms. The economic and societal costs of obesity tend to increase progressively with the BMI, but the health outcomes, at least for mortality, are J-or U-shaped. With some established chronic diseases, like diabetes, renal failure or cardiac failure, overfatness may be protective; sometimes this may be because contaminant fat-soluble endocrine disrupters are segregated in fat tissue. This means that some of the relatively favourable survival in the elderly who have more body fat is at the expense of the health care system. Younger children with chronic energy deficiency, on the other hand, may succumb before expenditure saves them. In these respects, our species is more vulnerable than we have thought. Fortunately, a better understanding of BMI and health is emerging.
体重指数（BMI）在肥胖识别方面对公共卫生和临床医学起到了很好的作用。然而，其应用也产生了一些具有启发性的矛盾和误解，这表明需要重视身体成分紊乱（BCD）本身，特别是要对肌肉量进行平行评估，并定义“正常肌肉量”状态，以便早期发现肌肉减少症。在整个生命周期中，考虑到性别和种族差异，BCD是所有营养相关疾病谱的基础。就糖尿病等代谢性疾病而言，肌肉、肥胖及其分布，甚至骨骼似乎都起着致病作用。最佳体脂及其分布与儿童发育、孕产妇健康和健康老龄化相关，关于其机制仍有许多有待了解之处。肥胖的经济和社会成本往往随着BMI的增加而逐渐上升，但健康结果，至少就死亡率而言，呈J形或U形。对于一些已确诊的慢性病，如糖尿病、肾衰竭或心力衰竭，超重可能具有保护作用；有时这可能是因为脂溶性内分泌干扰污染物被隔离在脂肪组织中。这意味着一些体脂较多的老年人相对较好的生存率是以医疗保健系统为代价的。另一方面，患有慢性能量缺乏的年幼儿童可能在支出节省之前就已死亡。在这些方面，我们人类比我们想象的更脆弱。幸运的是，对BMI与健康的认识正在不断提高。
