Direct calorimetry: a new clinical approach for measuring thermoregulatory responses in man.

The gradient layer direct calorimeter built in Lausanne allows proportionate measurement of respiratory and cutaneous heat losses. The latter consists of evaporative and convective plus radiative heat losses, which are separately measured. Obese subjects had lower heat losses and higher thermal body insulation than controls. The decreased heat loss may contribute to their positive energy balance by decreasing the energy cost of maintaining body temperature during cold exposure. The changes in heat loss during exercise are also illustrated.