Nature is unfair. Like all mammals, the human body maintains a certain temperature. A few degrees less is enough to disrupt everything, which can lead to weak immunity, or even pathogenic scenarios in extreme cases.
Sometimes the body deliberately tries to unbalance this balance. This is what happens when you have a fever, the aim of which is, among other things, to slowly cure the illness by getting rid of pathogens. Discover Magazine then asks: How does the body generate this heat, and why do some conserve it more than others?
Everything is based on metabolism, meaning the chemical reactions that take place in your body, specifically to produce the energy your body needs to function properly. The metabolism works like a car engine: it consumes fuel (food), burns it, and uses the resulting energy to move and produce heat. In the human body, this process of converting food into energy is called “cellular respiration” and thus about 50% of the calories we consume go towards maintaining our body temperature.
The body also uses other techniques to conserve heat. For example, shivering is a mechanism that vibrates the muscles and therefore releases more heat. It is this careful balance between heat production and loss that determines our overall body temperature.
How does cold tolerance vary between individuals?
As surprising as it may sound, it is primarily your body size and build that determines your cold tolerance. The larger the body, the more capable its metabolism is of heating its surface. Conversely, a person with a weak build finds it difficult to generate the required heat. This is why children especially need to be well covered, as they lose heat four times faster than adults.
This relationship between volume and surface area is particularly evident in other mammals, such as the shrew. This tiny species must push its metabolism to the limit, so that its heart beats more than 800 beats per minute. In comparison, the average human heart beats 60 to 100 times per minute. To keep up with this frenzied pace of energy consumption, shrews must eat very regularly, otherwise they will starve to death.
By extension, it is believed that women are more likely to catch colds than men because, on average, a woman’s body is smaller than a man’s. In a study published in 2021, researchers found that most women surveyed felt less comfortable than men in low temperatures. In contrast, men sweat more in the heat. This is due to different metabolic rates.
Other factors may play a role in body heat. For example, certain diseases like hypothyroidism and anemia can affect its production. People who are deficient in iron also produce less heat. Hemoglobin, the protein in red blood cells that carries oxygen throughout the body and fuels our internal furnace, requires iron to produce it. However, these factors remain more insignificant, and it seems that it is above all your body size that makes you wary or not.