Coffee induced thermogenesis and skin temperature.

The purpose of this study was to investigate the relationship between the changes in mean skin temperature and the energy expenditure induced by drinking coffee containing 4 mg of caffeine/kg body weight. Twelve healthy, weight-stable subjects were studied (five males, seven females; mean age +/- s.d., 25.3 +/- 3.3 years; BMI 22.5 +/- 3.1). Energy expenditure (EE) was measured by open-circuit indirect calorimetry, and skin temperature was determined with thermometric probes applied to the four body regions indicated by Ramanathan (chest, arm, thigh, calf). The calorimetric and thermometric measurements were carried out for 120 min with the participants lying down quietly. A significant correlation was found between the total thermogenic responses (net responses) and the temperature changes between 90 and 120 min from the coffee intake. Multiple regression analysis using mean EE after coffee intake as the dependent variable, and mean skin temperature and body weight as the independent variables yields the following equation: EE (kcal/min/m2) = -1.44 + 0.052 (mean skin temperature) + 0.004 (body weight). (r = 0.71 and P = 0.01) Our results indicate that small interindividual differences in mean skin temperature could explain energy expenditure differences in subjects with the same body weight, body composition and physical activity. This, in turn, could help explain variations in proneness to obesity.