NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
Obesity (Silver Spring). 2010 Jun;18(6):1092-9. doi: 10.1038/oby.2010.74. Epub 2010 Apr 1.
On entering a cold environment, people react by increasing insulation and energy expenditure (EE). However, large interindividual differences exist in the relative contribution of each mechanism. Short-term studies revealed that obese subjects increase EE (i.e., adaptive thermogenesis) less than lean subjects, which might have implications for the predisposition to obesity. In this study, we validate the differences in adaptive thermogenesis between lean and obese upon midterm mild cold exposure. Therefore, 10 lean and 10 obese subjects were exposed for 48 h to mild cold (16 degrees C) in a respiration chamber. The preceding 36 h they stayed in the same chamber at a neutral temperature (22 degrees C) for the baseline measurements. EE, physical activity, skin temperature, and core temperature have been measured for the last 24 h of both parts. Mean daytime EE increased significantly in the lean subjects (P < 0.01), but not in the obese. Physical activity decreased significantly in the lean (P < 0.01) and the obese (P < 0.001) subjects. The change in EE was related to the change in physical activity in both groups (respectively R(2) = 0.673, P < 0.01 and R(2) = 0.454, P < 0.05). Upon mild cold exposure, lean subjects decreased proximal skin temperature less, but distal skin temperature more than obese. In conclusion, the interindividual differences in cold-induced thermogenesis were related to changes in physical activity in both lean and obese, pointing at the existence of individual variation in physical activity to compensate for cold-induced thermogenesis. Furthermore, although a large part of the lean subjects counteracted the cold by increasing EE, most obese subjects changed temperature distribution, and therefore, increased insulation.
进入寒冷环境时，人们会通过增加隔热和能量消耗（EE）来做出反应。然而，个体之间在每种机制的相对贡献方面存在很大差异。短期研究表明，肥胖者增加 EE（即适应性产热）的程度低于瘦者，这可能对肥胖的易感性产生影响。在这项研究中，我们在中期轻度寒冷暴露时验证了瘦者和肥胖者之间适应性产热的差异。因此，10 名瘦者和 10 名肥胖者在呼吸室中暴露于轻度寒冷（16°C）中 48 小时。在此之前的 36 小时，他们在中性温度（22°C）的同一室中进行了基线测量。在这两个部分的最后 24 小时中，测量了 EE、体力活动、皮肤温度和核心温度。瘦者的日间平均 EE 显着增加（P <0.01），而肥胖者则没有。瘦者（P <0.01）和肥胖者（P <0.001）的体力活动显着减少。EE 的变化与两组中体力活动的变化相关（分别 R²=0.673，P <0.01 和 R²=0.454，P <0.05）。在轻度寒冷暴露下，瘦者减少近端皮肤温度的幅度较小，但减少远端皮肤温度的幅度较大。总之，冷诱导产热的个体差异与瘦者和肥胖者的体力活动变化有关，这表明个体之间存在体力活动的差异，以补偿冷诱导产热。此外，尽管大部分瘦者通过增加 EE 来对抗寒冷，但大多数肥胖者改变了体温分布，从而增加了隔热。
