Unit on Growth and Obesity, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-1103, USA.
Am J Clin Nutr. 2009 Nov;90(5):1124-31. doi: 10.3945/ajcn.2009.27567. Epub 2009 Sep 9.
Human obesity is associated with increased heat production; however, subcutaneous adipose tissue provides an insulating layer that impedes heat loss. To maintain normothermia, therefore, obese individuals must increase their heat dissipation.
The objective was to test the hypothesis that temperature in a heat-dissipating region of the hand is elevated in obese adults.
Obese [body mass index (in kg/m(2)) > or = 30] and normal-weight (NW; body mass index = 18-25) adults were studied under thermoneutral conditions at rest. Core body temperature was measured by using ingested telemetric capsules. The temperatures of the third fingernail bed of the right hand and of abdominal skin from an area 1.5 cm inferior to the umbilicus were determined by using infrared thermography. Abdominal skin temperatures were also measured via adhesive thermistors that were placed over a prominent skin-surface blood vessel and over an adjacent nonvessel location. The groups were compared by analysis of covariance with age, sex, race, and room temperature as covariates.
Core temperature did not differ significantly between the 23 obese and 13 NW participants (P = 0.74). However, infrared thermography-measured fingernail-bed temperature was significantly higher in obese subjects than in NW subjects (33.9 +/- 0.7 degrees C compared with 28.6 +/- 0.9 degrees C; P < 0.001). Conversely, infrared thermography-measured abdominal skin temperature was significantly lower in obese subjects than in NW subjects (31.8 +/- 0.2 degrees C compared with 32.8 +/- 0.3 degrees C; P = 0.02). Nonvessel abdominal skin temperatures measured by thermistors were also lower in obese subjects (P = 0.04).
Greater subcutaneous abdominal adipose tissue in obese adults may provide a significant insulating layer that blunts abdominal heat transfer. Augmented heat release from the hands may offset heat retention in areas of the body with greater adiposity, thereby helping to maintain normothermia in obesity. This trial was registered at clinicaltrials.gov as NCT00266500.
人体肥胖与产热增加有关；然而，皮下脂肪组织提供了一个隔热层，阻碍了热量的散失。因此，为了保持正常体温，肥胖个体必须增加散热。
本研究旨在验证肥胖成年人手部散热区域温度升高的假设。
在恒温环境下，让肥胖（体重指数（kg/m2）≥30）和正常体重（NW；体重指数=18-25）成年人在休息时接受研究。核心体温通过口服遥测胶囊测量。右手第三指甲床和腹部皮肤温度通过红外热成像仪从脐下 1.5cm 处的一个区域确定。腹部皮肤温度也通过贴在突出皮肤表面血管和相邻非血管位置的粘性热敏电阻器进行测量。通过协方差分析比较两组，以年龄、性别、种族和室温为协变量。
23 名肥胖参与者和 13 名 NW 参与者的核心体温无显著差异（P=0.74）。然而，红外热成像仪测量的指甲床温度在肥胖组显著高于 NW 组（33.9±0.7°C 比 28.6±0.9°C；P<0.001）。相反，红外热成像仪测量的腹部皮肤温度在肥胖组显著低于 NW 组（31.8±0.2°C 比 32.8±0.3°C；P=0.02）。热敏电阻器测量的非血管腹部皮肤温度在肥胖组也较低（P=0.04）。
肥胖成年人腹部皮下脂肪组织较多可能提供了一个显著的隔热层，削弱了腹部热量传递。手部散热增加可能会抵消身体脂肪较多部位的热量保留，从而有助于肥胖人群维持正常体温。本试验在 clinicaltrials.gov 注册为 NCT00266500。
