The body can only partially regulate water balance through the sensation of thirst as thirst is quenched before a sufficient amount of fluid has been drunk. In one study where subjects exercised in hot surroundings and were allowed to drink as much as they wanted, it was found that only 70% of the fluid needed to restore the loss was consumed. In another study, the fluid intake of three groups of soldiers marching in a temperature of 25°C was monitored.