You probably dismiss it as just another old saying. But when ladies insist that they glow rather than sweat, they may not be so far off the truth.
Researchers say women really do sweat far less than men, particularly during intensive exercise.
On average, they tend to perspire half as much after similar amounts of physical activity in the same temperatures.
Sweating is an essential bodily function which cools us down. As we release fluid through our skin it evaporates, and this process takes heat from the body, lowering our overall temperature.
Scientists believe that thousands of years ago men evolved to sweat more than women as they tended to be more active.
They needed to cool down quickly while hunting wild animals in sweltering heat, for example.
By contrast, women evolved to sweat less, the experts believe. Their smaller bodies contain less water than men’s so if they perspire too much, there is a danger they will become dehydrated.
The Japanese researchers warn that women may be more at risk from heat stroke as their bodies are not as good at naturally cooling themselves down.
But the scientists also discovered that very fit people sweat the most, regardless of sex. Someone who plays a lot of sport will give off 60 percentmore bodily fluid during exercise than someone of the same sex who is relatively inactive.
They believe that we would find it easier to cope with heatwaves if we took more exercise.
Yoshimitsu Inoue, who led the study at the Universities of Osaka and Kobe said: “Women generally have less body fluid than men and may become dehydrated more easily.“
Therefore, the lower sweat loss in women may be an adaptation strategy that attaches importance to survival in a hot environment, while the higher sweat rate in men may be a strategy for greater efficiency of action or labour, they believe.
“Both men and women can acclimate themselves better to heat if they exercise regularly before a heat wave comes.”
The study, published in the journal Experimental Physiology, looked at 37 women and men, half of whom were fit and half unfit. Volunteers were asked to pedal an exercise bike for an hour while the researchers measured their sweat output.
The scientists discovered that the difference between men and women’s sweating became more extreme the longer they cycled.
An average person sweats between one and one-and-a-half litres a day depending on their sex, the temperature and how active they are. Football players lose two litres of sweat in a match, while elite marathon runners can lose three litres in an hour.
Often, we sweat when we are nervous, but usually only in places such as the palms, armpits or soles of the feet. During exercise, however, we sweat all over.
Many believe that sweating releases harmful toxins from the body, which is why many go to saunas, but there is no scientific evidence to support this.