When it comes to hot weather, two distinct camps emerge: those who love the heat and those who hate it. It’s a matter of preference, some might say – but also of physical constitution.
Indeed, we’re not all equal when it comes to heat. Some people tolerate it less well than others, depending on a number of factors including age, gender, build and hormonal balance.
Human beings are homeothermic animals, meaning we keep our core temperature relatively constant despite any changes in the surrounding conditions. But, at the same time, our bodies naturally produce heat, which also makes us endothermic creatures, like other mammals.
When our bodies are exposed to intense heat, they thermoregulate by producing sweat. It is the evaporation of this sweat through the pores of the skin that evacuates the heat, thus lowering the body’s temperature.
But this internal climate-control system doesn’t work in the same way for everyone. Babies and older people sweat less than adults, which explains why they are so sensitive to ambient heat. They are also more likely to suffer from dehydration, as they don’t tend to feel as thirsty.
Yet the body needs a sufficient supply of water to produce sweat and adjust its core temperature.
In addition, our ability to withstand high temperatures depends on biological sex. The assumption that women are more sensitive to heat than men is confirmed by numerous scientific studies.
For example, research from the Netherlands, published in 2021 in the journal International Archives of Occupational and Environmental Health, reports that deaths during heatwaves are higher among women than men. These differences are due to a number of possible causes, including differences in height, weight, perspiration, cardiovascular strain and hormones.
However, it would be wrong to say that women’s greater discomfort is solely linked to biology. It also stems from social factors, with the Dutch researchers explaining that women are less likely than men to be well-equipped to cope with the heat due to income inequalities.
How to better tolerate heat
In addition to the physical differences between individuals, heat tolerance is closely linked to lifestyle. When temperatures rise, many people turn on the air conditioning. And while this may be a good idea in the “heat” of the moment, it can be less so in the longer term: the stronger the air conditioning, the greater the difference with the outside temperature.
This puts our bodies to the test when we leave the air-conditioned space: too severe a change in temperature (over 10°C) could lead to thermal shock, even loss of consciousness or – in a worst-case scenario – cardiac arrest. So, it’s best to use air conditioners sparingly.
Diet also has an impact on tolerance to high temperatures: fatty or high-protein foods contain compounds that are relatively difficult to digest. Our bodies have to expend more energy to process them and, therefore, generate more heat.
That’s why we often sweat profusely after eating sausages, burgers and other grilled meats at a barbecue. When the mercury rises, opt for light meals with vegetables, lean meats or fish instead. Similarly, it’s important to limit alcohol consumption.
Generally, it’s perfectly possible to change your habits to acclimatise better to heat. And that’s good news as the effects of global heating become more keenly felt: from February 2023 to January 2024, the global surface air temperature was 1.52°C higher compared to pre-industrial levels of 1850-1900, according to the EU’s Copernicus monitoring programme.
In this context, we’re going to have to be adaptable if we’re to learn to live in a world where our tolerance to heat will be increasingly challenged.