肥胖與老化是世界兩大重要趨勢並和許多慢性疾病、失能與死亡率相關。「肥胖」指的是營養攝入多而能量消耗少，致使身體有過多脂肪堆積的慢性過程。老化引起身體組成的改變，使脂肪細胞堆積在内臟且浸潤到肌肉細胞的同時，肌肉質量與肌力也漸漸減少。老人若同時存在肥胖與肌肉質量和肌力過低，我們稱之為「肌少型肥胖症」，其對骨頭健康、心血管風險、代謝症候群與死亡率的危害遠較兩者單一存在時為大。肌少型肥胖症起因於身體活動減少、基礎代謝率下降並受到發炎反應、胰島素阻抗、荷爾蒙調節等體内因子的影響。要打破這樣的惡性循環，最有效的介入性治療是營養與運動並行，藉由規律的有氧與阻抗運動搭配低熱量高蛋白飲食來改善。藥物治療如肌生成抑制素的抑制劑、生長激素釋放激素類似物等則仍需進一步研究探討。

Obesity and ageing, highly related to chronic illness, physical ability and mortality, are two main trends worldwide. Obesity is a chronic excess of nutrient intake relative to the level of energy expenditure and stored as an excess of adipose tissue. Given the age-related changes in body composition, the adipocyte accumulates in the visceral area and infiltrates into the muscle cells while the muscle mass and muscle strength decreases. Obesity and loss of muscle mass and strength may coexist in some elders, so called sarcopenic obesity (sarcobesity). Sarcobesity may pose a negative synergic effect to bone health, cardiovascular risk, metabolic syndrome and mortality. The etiology of sarcobesity includes sedentary lifestyle and decreased basal metabolic rate, followed by inflammation response, insulin resistance and hormone regulation. To break down the vicious circle, the most beneficial treatment is diet and exercise intervention. Sarcobesity could be reduced by regular aerobic and resistance exercise combined with low energy and adequate protein diet. Pharmacologic therapy such as myostatin inhibitors or growth-hormone-releasing hormone analogs may have a role in the treatment of sarcobesity that requires further investigation.