Thermic Effect of Glucose and Thermal Body Insulation in Lean and Obese Subjects: a Calorimetric Approach

The fact that many obese subjects have a tendency to gain weight with no real excess of food intake is generally accounted for by a low physical activity (Bullen, Reed & Mayer, 1964). Although a few authors have claimed that the efficiency of energy utilization could be greater in obese than in lean subjects (Galton & Bray, 1967)’ there is no clear evidence to support this concept. In a period of weight gain, the positive energy balance in the obese can be explained by a relative excess of energy intake in relation to a decreased energy expenditure. The latter may be due partly to lack of muscular exercise, but other factors may contribute to save energy in the obese such as impairment of glucose oxidation with a low thermic effect (specific dynamic action) or decreased heat losses during cold exposure resulting from an elevated body thermal insulation. Since this symposium is concerned with ‘Applications of human and animal calorimetry’, I will briefly describe the methods of direct and indirect human calorimetry used in Lausanne.