There's a common belief that women generally feel colder than men, but is that really backed by science?
Actually, the evidence is mixed, in part because few studies addressing this question have been conducted in a carefully controlled manner. That said, the data gathered to date suggest that people's perception of and ability to regulate body temperature rests not on their sex, but rather on their physical traits — in particular, their body fat and surface area.
A lot of past research does seem to support the idea that women often feel colder than men. This has included survey-based studies that probed people's preferred thermostat temperatures in office settings.
Research also suggests that, on average, women have slightly higher core temperatures than men, but their hands, feet and ears tend to be colder. This may be related to women's two main sex hormones: estrogen and progesterone. Estrogen dilates blood vessels in the extremities, allowing heat to escape; meanwhile, progesterone can constrict blood vessels in the skin, boosting core temperature but limiting blood flow to the extremities.
Related: Has the average human body temperature always been the same?
This explanation hints at why women might feel colder than men — but again, there's likely more to the story.
Several recent, well-designed studies have found that a person's body temperature regulation depends less on their sex and more on their physical traits. For example, in a small study published in the journal PNAS, scientists at the National Institutes of Health (NIH) found evidence that women and men perceive temperatures in a similar manner and don't show any major, sex-based bodily differences in how they respond to cold.
"We tried to figure out what happens at the temperature at which people start to shiver — where they are cold but not fully overtly shivering," said lead study author Robert Brychta, an NIH staff scientist.
In the study, 12 women and 16 men, all fairly lean, each stayed in a room as the scientists varied the temperature from hot to cool — roughly 88 degrees Fahrenheit (31 degrees Celsius) to about 63 F (17 C). The participants wore standardized outfits, as well as sensors that tracked electrical activity in their muscles and their skin temperatures.
A "calorimeter" measured the amount of oxygen people breathed and carbon dioxide they expelled; this helped the researchers track the amount of energy expended. People's weights, heights, body-fat percentages and basal metabolic rates were also recorded, as these factors affect heat production.
Participants also rated their perception of the room temperature using a visual sliding scale from "very cold" to "very hot."
Men's and women's temperature perception was the same throughout the experiment, and they also shivered to the same extent at colder temperatures. The coldest temperature they could tolerate before shivering was the same, at about 68 F to 70 F (20 C to 21 C).
The participants' skin temperatures were similar during the experiment, although, on average, women had slightly warmer skin than men did. Other physiological measurements — such as the electrical activity of their muscles — were also pretty much the same, but women's basal metabolic rates were slightly lower than men's.
Women did maintain slightly higher core body temperatures at cold temperatures than men did. This may be because the women, on average, had higher body fat percentages than men and thus more insulation, the researchers wrote in the paper. The temperature at which women's bodies started spending energy to stay warm — what the researchers called the lower-critical temperature — was also a touch lower than men's, by about 1.8 F (1 C), on average.
Taken together, the results suggest that women and men react to temperature changes in a similar way. Any differences you might observe from person to person rest on their individual differences in body composition.
"It is the interaction of the body surface area and the body fat percentage that contributes to where the lower-critical temperature falls," not a person's sex, Brychta told Live Science. "Though we see some differences between men and women, really, it's like an individualized point." For example, a taller woman with little body fat would likely have a warmer lower-critical temperature than a smaller man with more body fat.
The study led by Brychta and his colleagues was small in size, but it does start to challenge the notion that women always feel colder than men, writ large.
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