By Dr. Mercola
You're born with anywhere between 2 million and 4 million sweat glands, and the number of such glands will determine, in part, how much you sweat. While women generally have more sweat glands than men, it’s long been said that men's glands tend to be more active and produce more sweat.1
It turns out, however, the widespread notion that men sweat more than women may not be accurate after all.
Instead, differences in sweating may have much more to do with body size than they do with sex, as researchers from the University of Wollongong in Australia and Mie Prefectural College of Nursing in Japan revealed that a person’s sex explained no more than 5 percent of the variances in individuals’ responses to heat, including sweating.2
Body Shape and Size May Dictate How Your Body Cools Off
To understand the new study findings, it helps to first be aware of the two primary ways your body cools itself down: sweating and increasing circulation to your skin’s surface. You don’t get to consciously choose which route your body turns to when it starts to heat up, so what’s the determining factor in which method your body favors?
Researchers conducted a study with 24 men and 36 women who took part in two trials, one involving light exercise and the other moderate exercise.3
The workouts were performed at just over 82 degrees F (28 degrees C) and 36 percent humidity, which are conditions at which the body can successfully regulate its temperature using one of the two methods mentioned.4,5
Body temperature changes were the same in all participants, male or female; however, smaller men and women with more surface area per kilogram of body mass tended to cool down primarily by increasing blood flow to their skin — and less so by sweating.6
“Gender is sometimes thought to independently modulate cutaneous vasomotor and sudomotor [sweat glands] function during heat exposure.
Nevertheless, it was hypothesized that, when assessed during compensable exercise that evoked equal heat-loss requirements across participants, gender differences in those thermoeffectors would be explained by variations in the ratio between body surface area and mass (specific surface area).
… It was concluded that, when assessed during compensable exercise, gender differences in thermoeffector function were largely morphologically determined, rather than being gender dependent.”
Past Research Has Hinted at Sex Differences in Sweating
The featured study adds a new perspective to the science of sweating, but it’s far from the only one. Multiple previous studies have suggested that a person’s sex does appear to play a role in temperature regulation during heat stress (i.e, exercise).
One review concluded, “… [O]bservations clearly establish sex differences in sudomotor activity during exercise, independently of differences in physical characteristics and rate of metabolic heat production.”9 Those findings suggested women may have a lower maximal sweat rate during exercise.
Another intriguing study looked into sweating rates not only among men and women, but among men and women of different fitness levels (trained versus untrained). The participants exercised on stationary bikes in an 86-degree F room and gradually increased exercise intensity as the workout went on (for a total of one hour).10
While the fit men sweat the most, they did so using a similar number of active sweat glands as the fit women, but the women produced less sweat from each gland. In contrast, the unfit women sweat the least and faced rising body temperatures before finally sweating at full capacity.11
Study author Yoshimitsu Inoue, Ph.D., a professor of physiology at Osaka International University, told The New York Times:12
“It appears that women are at a disadvantage when they need to sweat a lot during exercise in hot conditions …
[The] lower sweat loss in women may be an adaptation strategy that attaches great importance [to preserving body fluids] for survival [while] the higher sweat rate of men may be an adaptation strategy for greater efficiency of action or labor.”
What Else Influences How Much You Sweat?
Everyone is different in how much sweat is released as a result of rising temperatures. Overweight people tend to sweat more than those who are a healthy weight, which lends more credence to the featured study’s findings that body size plays a role.
Beyond this physical characteristic, your levels of stress and anxiety also influence sweating.
Even in cases of hyperhidrosis, which is the medical term for excessive sweating, the sweating tends to be worse when you're under stress and is thought to be triggered by your body's stress response. Johns Hopkins pediatrician Dr. Kate Puttgen told Medical Daily:13
"The cause of primary focal hyperhidrosis is not well understood but is thought to originate from overactivity of the sympathetic 'fight-or-flight' nervous system sending aberrant signals to the major sweat glands of the body."
Drinking alcohol and smoking can trigger sweating, as can too much caffeine.14 Medical conditions, such as hypothyroidism, can also influence sweating. Hypothyroidism is a very common cause of inability to sweat (also known as anhidrosis or hypohidrosis) in women.
While this may sound like a good thing, it can be life threatening, and those affected are at increased risk of heat exhaustion and heat stroke.15 On the other hand, diabetes, gout, hyperthyroidism, Parkinson’s disease and heart failure are examples of medical conditions that can lead to excessive sweating.16
Do You Know About the Two Types of Sweat Glands?
You have two different types of sweat glands: eccrine sweat glands, which are distributed over your entire body, and apocrine sweat glands, located on your scalp, armpits and genital area. The primary purpose of eccrine glands is to regulate your body temperature.
As your body temperature rises, your body will automatically perspire to release salty liquid from your sweat glands to help cool you down. This is controlled by your autonomic nervous system, which you cannot consciously control. According to the International Hyperhidrosis Society:17
“Sweat is essential to human survival because it serves as the body's coolant, getting rid of excess body heat (produced by your metabolism and working muscles) and protecting you from overheating. In fact, even people who don't have hyperhidrosis are constantly sweating; they just might not notice it.
Whenever your body temperature begins to increase, your autonomic nervous system stimulates your eccrine sweat glands (the average person has 2.6 million of them) to secrete fluid onto the surface of your skin. As this fluid (called perspiration or sweat) evaporates, your body starts to cool down. Under normal circumstances, a single pea-sized bead of sweat can cool nearly 1 liter (about 1 quart) of blood by 1 degree Fahrenheit.”
The Emotional Side of Sweating
Certain emotions, such as anxiety, anger, embarrassment or fear, can prompt you to sweat more. This — your emotions — is a prime trigger of sweat from your apocrine glands. These glands, by the way, also produce bacteria to break down the sweat, and this process causes body odor.
This is why body odor comes primarily from under your arms — not so much from the sweat that forms on your chest or arms, for instance. In addition, sweat produced from exercise or overheating is made up primarily of water and salt. Sweat produced when you're stressed also contains water and salt, along with fatty substances and proteins, which interact with bacteria leading to a distinct odor.
Interestingly, people can detect the difference between stress sweat and exercise sweat — and may even change their perception of you because of it. In one study published in the journal PLOS One, men who sniffed women's stress sweat rated them as less confident, trustworthy and competent.18
Why Sweating Is Good for You
Sweating is an essential element of keeping your body temperature regulated, but it offers benefits even beyond that. Sweating acts as an important route of detoxification, including helping to excrete toxic metals like arsenic, lead and mercury.19 It’s been used since ancient times as part of worldwide traditions, from Roman baths and Scandinavian saunas to Aboriginal sweat lodges. Researchers writing in the Journal of Environmental and Public Health explained:20
"Sweating with heat and/or exercise has been viewed throughout the ages, by groups worldwide, as 'cleansing' … Sweating offers potential and deserves consideration, to assist with removal of toxic elements from the body.
… Sweating is not only observed to enhance excretion of the toxic elements of interest in this paper, but also may increase excretion of diverse toxicants, as observed in New York rescue workers, or in particular persistent flame retardants and bisphenol-A … Optimizing the potential of sweating as a therapeutic excretory mechanism merits further research."
The researchers noted the following promising roles of sweat in detoxification:
- Sweat may be an important route for excretion of cadmium when an individual is exposed to high levels
- Sweat-inducing sauna use might provide a therapeutic method to increase elimination of toxic trace metals
- Sweating should be the initial and preferred treatment of patients with elevated mercury urine levels
How Much Sweating Is 'Normal?'
What’s normal for you may be abnormal for someone else, so it’s hard to pinpoint a “normal” amount of sweating. That being said, many people make efforts to sweat less when in reality they should be taking advantage of opportunities to sweat more.
The use of antiperspirants, which use antimicrobial agents to kill bacteria and other ingredients such as aluminum to block your sweat glands, is one such example that should be avoided (washing with soap and water should be enough to keep the area odor-free). On the other hand, breaking a sweat while you exercise is one reason why physical activity is good for you.
While virtually any type of intense exercise will lead to sweating, exercising in warm temperatures (or in a heated room, such as in Bikram yoga) will create even more sweating. As noted, if you're fit, your body will sweat earlier and easier. Many people frown on this but it’s actually a benefit, because the sooner you start sweating the sooner your body cools down, and this allows you to continue exercising harder and longer.
You can also induce sweating via a sauna, either traditional or infrared. Infrared saunas are a great option and can significantly expedite the detoxification process. Hyperthemic conditioning, or "acclimating yourself to heat independent of aerobic physical activity through sauna use," appears to also lead to earlier and easier sweating, similar to being fit.21
If you’re concerned that your level of sweating isn’t “normal” — either too much or too little — make an appointment with a holistic health care provider to rule out any potential underlying medical conditions.