South Asians (SAs) develop type 2 diabetes at lower body mass index values than white Europeans (WEs). This basic human experimental study aimed to compare the metabolic consequences of weight gain in SA and WE men without overweight or obesity. Fourteen SAs and 21 WEs had assessments of body composition, metabolic responses to mixed-meal ingestion, cardiorespiratory fitness and physical activity, and a subcutaneous abdominal adipose tissue biopsy, before and after 4–6 weeks of overfeeding to induce 5–7% weight gain. Here we show that body mass index and whole-body adipose tissue volume increases similarly between ethnic groups, but SAs gain less lean tissue. SAs experience a substantially greater decrease in insulin sensitivity compared with WEs (38% versus 7% decrease, P = 0.009), have fewer small (37.1% versus 60.0%, P = 0.003) and more large (26.2% versus 9.1%, P = 0.005) adipocytes at baseline and have a smaller decrease in very small adipocytes with weight gain (−0.1% versus −1.9%, P < 0.0001). Ethnic differences in adipocyte morphology are associated with SA’s greater adverse metabolic changes with weight gain. ClinicalTrials.gov registration: NCT02399423.

南亚人 (SA) 患 2 型糖尿病的体重指数低于欧洲白人 (WE)。这项基本的人体实验研究旨在比较体重增加对没有超重或肥胖的南澳和西澳男性的代谢影响。 14 名 SA 和 21 名 WE 在过度喂养 4-6 周以导致体重增加 5-7% 之前和之后对身体成分、混合膳食摄入的代谢反应、心肺健康和体力活动以及皮下腹部脂肪组织活检进行了评估。在这里，我们发现种族群体之间的体重指数和全身脂肪组织体积增加相似，但 SA 获得的瘦肉组织较少。与 WE 相比，SA 的胰岛素敏感性下降幅度更大（下降 38% 与 7%， P = 0.009），较小的胰岛素敏感性较少（37.1% 与 60.0%， P = 0.003），较大的胰岛素敏感性较大（26.2% 与 9.1%， P = 0.003）。 = 0.005) 基线时脂肪细胞的数量减少，并且随着体重增加，非常小的脂肪细胞减少幅度较小（-0.1% 与 -1.9%， P < 0.0001）。脂肪细胞形态的种族差异与SA随着体重增加而产生的更大的不利代谢变化有关。 ClinicalTrials.gov 注册：NCT02399423。