I am a woman. Why am I always so cold? - Chia Sẻ Kiến Thức Điện Máy Việt Nam

I am always cold. I’ve had this problem ever since I was a child, when I’d sneak into the living room in the winter and turn up the thermostat while my parents weren’t looking. When I still worked in an office (pre-pandemic), I noticed that often my female colleagues and I would be wearing sweaters in the dead of summer to keep warm in our over-air conditioned building. Yet my male colleagues seem impervious to the cold – often wearing short-sleeves.

Which led me to wonder: Do women feel cold more than men and if so, can science explain this difference?

Take-home message:
– Women produce less heat than men due to slower metabolic rates, so they tend to feel colder more quickly when temperatures drop
– Muscle, the size of the body’s surface area and even the hormones we produce all affect how we sense heat and cold
– Buildings’ thermostats should be set at temperatures that take into account our gender differences in how we sense the cold

Mục Lục

Metabolism and heat

As many women know, it can be tougher for us to lose weight than men. Blame our slower metabolisms. A study in the Journal of Applied Physiology showed that the resting metabolic rate, or the amount of energy your body burns at rest, was 23% higher in men than women. A slower metabolism causes women to produce less heat so they tend to feel colder.

“It’s simple physics,” says Boris Kingma, PhD, a thermophysiologist, at The Netherlands Institute for Applied Science (TNO). “If you lose more heat than your body produces, your body temperature will go down and you will sense that.”

And things don’t improve with age. Our metabolic rate tends to slow as we get older, regardless of gender.

Insulation: Inside and out

The easiest way to warm up if you’re cold is to change your behavior – that’s where the heavy sweaters or space heaters for our over-air-conditioned offices come in. “These kinds of actions are basically how we were able to conquer the entire planet and survive in the arctic as well as the desert,” says Kingma.

But failing that, your own body can help warm you up as well. If you can’t change the external temperature with your behavior and you aren’t making enough heat through your metabolism, your body may try to insulate your tissues by constricting the blood vessels in your hands and feet to slow the blood flow. That way less heat from the core escapes to the extremities.

It’s really important to keep up the temperature of your core, where your vital organs are. If that drops too much, hypothermia sets in. But this comes at a cost: Our extremities don’t function as well. Then over time, this reduced blood flow can increase the risk of cold weather injury (that is why you hear of so many lost fingers and toes due to frostbite among arctic explorers).

So then what about fat? I tend to gain weight in the winter but at least I figured it helps insulate me against the cold. And while body fat does provide some insulation, it isn’t nearly as good at keeping us warm as muscle, as this University of Cambridge study shows. Muscle is great at generating heat, which is the other reason men have higher metabolisms than women – they generally have more muscle.

What’s on the surface matters

Then there is also the issue of surface area. When you look at the amount of heat the body produces relative to its surface area, women tend to produce less heat per unit of surface area, says Kingma. They also tend to lose heat more quickly since they have a higher surface area compared to the total volume of their bodies.

The same is true with your hands, which also have a large surface area‐to‐volume ratio (hands have a lot of skin but not a lot of mass). So it’s no coincidence that one of the first signs of being cold are cold hands. And that will probably happen sooner in women, which may be how the saying “cold hands, warm heart” came about. This Lancet study, which looked at 219 men and women aged 1 to 84, found women’s hands were about 1.5 degrees Celsius colder than men’s.

Blame hormones, evolution

Estrogen can lower women’s body temperature, cause heat to dissipate and slow blood flow to the hands and feet, making them more sensitive to cold. And depending on the phase of your menstrual cycle and varying hormone levels, research, like this Polish study, shows the female body can change how it regulates heat. To read more about women’s basal metabolic rates and menstruation, check out this Skeptical Inquirer story by Ada McVean.

Evolution may also play a role in how we handle heat. We evolved in much warmer climates, like the savannah, where it was important to stay cool. A more temperate climate may have meant there was less of a need to warm up. Men were far more active as they went off hunting and gathering, while women led more sedentary lives, tending to the children and the home. Being bigger, more active and having more muscle all meant men had more need to evolve ways of not overheating – the most common one being sweating. So that may also be why men sweat more than women.

So why is my office so cold?

Kingma led a study published in Nature Climate Change that looked at how women’s lower metabolic rate is related to the temperature they feel most comfortable at. There is some overlap, but that temperature tends to be higher for women than for men. But it turns out, at the time of the study, most workplace thermostats were set based on a model developed in the 1960s that only takes into account male metabolic levels and may overestimate female metabolic rates by up to 35%.

Too cold offices may also be hampering women’s productivity. A University of Southern California study found that women performed better on math and verbal tasks at higher temperatures than men. And while the men performed better at lower temperatures, the effects were less pronounced.

So it seems like raising the temperature in our offices could be a win-win. Women’s productivity may increase, it is more energy efficient and I could ditch my summer office sweater.