In summer, we are not all equal when it comes to heat

When the warm weather arrives, two distinct camps appear: those who love the heat and those who hate it. Each tribe has its own rituals and interests. The former dream all year long of flying away during the summer to warm destinations, while the latter travel more to northern lands to avoid the scorching temperatures.

A matter of taste, some will say. But also of physical constitution. For good reason, we are not all equal when it comes to summer heat. Some people tolerate it less than others, whether it is dry or humid. These inequalities in feeling depend on multiple factors, such as age, sex, corpulence or even hormonal status.

As a reminder, humans are “homeothermic” animals, meaning that their core temperature is relatively constant and independent of ambient conditions. But at the same time, our bodies naturally produce heat, which also makes us “endotherm” creatures, like other mammals. When our bodies are exposed to high temperatures, they thermoregulate by producing sweat. It is the evaporation of this same sweat through the pores of the skin that allows heat to escape and therefore lowers the body’s temperature.

Biological inequalities

But this internal air conditioning system doesn’t work the same way for everyone. Babies and older people sweat less than adults, which is why they’re so sensitive to ambient heat. Both groups are also more likely to be dehydrated because they’re less thirsty. The body needs enough water to produce sweat and regulate its core temperature.

In addition to age, our ability to tolerate high temperatures more or less well depends on our biological sex. The intuition that women are more sensitive to heat than men is confirmed by numerous scientific studies. A Dutch studypublished in 2021 in the International Archives of Occupational and Environmental Health, shows that deaths during heatwaves are higher among women than among men.

These differences could be due to several possible causes, such as differences in height, weight, sweating, cardiovascular pressure, or even hormones. However, it would be wrong to say that women’s greater discomfort in summer is solely related 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 inequality.

Changing your habits to better cope with the heat

In addition to physical differences between individuals, resistance to heat is closely linked to each person’s lifestyle. In the event of extreme heat, many people automatically turn on the air conditioning. A good idea at the time, but much less so in the long term. The stronger the air conditioning, the greater the difference with the outside temperature. This puts our body to the test when it leaves the air-conditioned space. A change in temperature that is too violent (more than 10°C) exposes us to thermal shock, with, in the worst case, loss of consciousness or even cardiac arrest. It is therefore better to exercise moderation with air conditioners.

Our diet also has an impact on our tolerance to high temperatures. Fatty or high-protein foods contain molecules that are relatively difficult to digest. Our body must expend more energy to assimilate them, and therefore generate more heat. This is why we often sweat profusely after eating chipolatas, merguez sausages and other grilled foods at a barbecue. When the mercury goes crazy, opt for light meals with vegetables, lean meats or fish. Similarly, it is important to limit your alcohol consumption.

Generally speaking, it is entirely possible to change your habits to become more acclimatized to the heat. This is good news when you consider that the effects of global warming are being felt more acutely. Over the period from February 2023 to January 2024, the global air temperature on the surface of the globe was 1.52°C higher than in the period 1850-1900, according to the European Copernicus Institute. In this context, we will have to be adaptable to learn to live in a world where our tolerance to heat will be increasingly challenged.