We often hear that “women are always colder than men”, but in reality things are much more complex and even if there are differences related to factors organic, hormonal And physicistsrecent studies highlight how it’s not just a gender issue. What most influences body temperature and the preference between cold and heat are the body composition and basal metabolismthat is, the energy we consume with activities that are simply necessary for survival (such as breathing and blood circulation).
Biological differences between men and women
Historically, the explanation why “women are always cold” has been linked to several factors, such as body composition and surface area, basal metabolism and hormonal components.
Women have on average 6 to 11% more fat tissue than men, which is helpful in keeping the internal organs warm, providing greater insulation from the outside. But at the same time reases the heat transfer to the skin and extremitieswhich are therefore more cold. In addition, women have a minor percentage Of mass muscular compared to men (always speaking in general terms) and since muscles are the main producers of energy And heathaving less of it produces less heat. This also affects the basal metabolism, which on average is lower in women than in men.
Generally, women have a smaller body size than men and a higher ratio between skin surface area and body mass: as a result, we lose more easily the little heat we produce.
Finally, it should be considered thehormonal aspectwith the fluctuations of estrogens And progesterone which influence the thermoregulation with a complex and still unclear process, causing an increase in basal temperature of 0.3 °C – 0.7 °C during the post-ovulatory luteal phase.
Body mass and basal metabolism matter more than gender
Despite everything, many recent studies are demonstrating that These biological differences are actually negligible.
An initial study conducted only on men had paved the way by recognizing the importance of body size, body composition and basal metabolism in thermoregulation. But more and more studies confirm that eliminating biological differencestherefore with the same basal metabolism and body mass and composition, there are no differences of body temperature or perception of external temperature between men and women.
Indeed, according to a very recent study published in PNAS, women prefer the cold, finding an ambient temperature of 22°C ideal, one degree less than men. In this study, the lower critical temperaturethat is, the minimum temperature at which thermoregulation works without activating the thermogenesis systems (such as shivering).
The result was that women “resist”, and therefore activate these defense systems, at lower temperatures than men, probably due to the higher percentage of insulating adipose tissue. Furthermore, the study further confirms that, given the same body mass and basal metabolism, what matters in feeling cold or hot is not the sexual gender in itself, but one’s own body shape and body composition, as well as the amount of energy we consume (also influenced by our lifestyle, among other things).
Social choice and still much to study
It seems that this temperature difference is also present among animals, with females preferring warm environments, while males stay in areas with low temperatures. But researchers also associate this behavior with a social component: females take care of the puppieswhose thermoregulation is still under development. Furthermore, spatial separation would guarantee a better division of food resources and would allow females to protect their offspring, which in many species are preyed upon by males. It therefore seems more like a social choicewhich is dictated by biology.
The reality of the facts is that the female body is still an unknown territoryso there are few well-structured studies on thermoregulation, as well as on medicine in general. In 1977, the Food and Drug Administration (FDA) even recommended excluding women of childbearing age from phase 1 and 2 clinical trials. This choice, born as a precaution to avoid problems in the case of pregnancies and to reduce the variability in the results linked to hormonal fluctuations, has in fact led to the almost total lack of data on the effects of many drugs on women.
Only since the 1990s has the inclusion of women in the early stages of clinical trials become law, but despite this, their presence is still very low, making further studies necessary to understand the mechanisms of female body health.
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