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Let’s talk about sweat

Sweating is a natural bodily function—all of us sweat regardless of age, gender, or intensity of physical activity. Sometimes we notice changes in how much we sweat or how our sweat smells. There are reasons for these changes.

Engaging in Perspiration Dialogue - Let's Explore the Science of Sweat.

Sweating or perspiration is the body’s natural cooling mechanism: body temperature goes down as drops of sweat appear on the skin and evaporate.

Sweating is also one way the body cleanses itself of toxins. How much we sweat and how our sweat smells can give us clues about what our bodies are going through.

Regardless of physical activity or temperature, we lose about half a litre of fluid per day via sweating.

We start to feel ourselves sweat once loss of liquid exceeds half a litre. This is especially noticeable in high heat, in the sauna, or during physical activity. When exercising, the muscles generate a large amount of heat, triggering the body to sweat.

Apart from heat, another common reason for sweating is stress. We sweat in tense situations and certain body parts tend to sweat more than others—the face, palms, neck, armpits, wrists, and feet.

How sweat is formed

The process of sweating is controlled by the sympathetic and parasympathetic nervous systems. Sweat is released by two types of glands: the eccrine and apocrine glands.

  • The eccrine glands are found all over the skin, including the feet, palms, forehead, cheeks, and armpits. They emit a clear, odourless sweat made up of water and salt. This is the main body coolant.
  • The apocrine glands are located in the armpits, under the breasts, around the navel and in the genital area. The sweat produced by these glands contains various proteins, peeled skin cells, and fatty acids, which react when they come into contact with oxygen and bacteria. This is how each person acquires their own unique body scent.

Sweat that has been on your skin for a while acquires an unpleasant odour because it comes into contact with bacteria that live on the skin. The longer the sweat stays, the stronger you smell.

Why does the smell of sweat change?

Sometimes your sweat may seem to have a stronger smell than usual. This can be caused by a variety of things but the most common of these is food. The more potent the food (spices, onions, garlic, etc.), the more potent the sweat.

The moisture content of sweat comes from blood plasma—a colourless fluid in which red and white blood cells, salt, and other things are suspended. If the food we eat contains water-soluble aromatic substances, they are also absorbed by our body fluids. Most of the fluid leaving the body is excreted by the kidneys as urine, the rest is released through the skin in the form of sweat.

Microscopic aromatic particles that enter the body through the food we eat can change the way our sweat smells.

Exploring Diet and Sweat - Understanding the Influence of Meat and Animal Protein on Body Odor

Some sources indicate that eating meat and other forms of animal protein create stronger-smelling sweat. Other foods that affect the smell of sweat include cabbage, cheese, coffee, chocolate, lemons, and alcohol. Not only does alcohol change the smell of sweat, it also increases the amount of sweat we produce. Some medications produce a medicinal smell in your sweat that disappears once you stop taking them.

In addition to foods and medications, vitamins also play a role in the odour of sweat. The B vitamin choline can cause a fishy odour and excess B-1, thiamine, can add a strong smell to both sweat and urine. One of the most common side effects of overdosing on selenium supplements is the smell of garlic in your breath and sweat;  a person with such high selenium levels requires immediate medical attention.

Excessive sweating

Women tend to sweat more during menopause. When the body no longer has a need to regulate ovulation and menstruation, oestrogen and progesterone levels naturally drop. These hormones influence other hormones that regulate the body’s temperature. Some women experience hot flashes and heavy sweating during this time. The good news is that these symptoms disappear once the body has completed the transition.

Being overweight contributes to increased sweating. More weight makes the body work harder, even when performing simple tasks. Working hard means more heat, which means more sweating.

Another cause of excessive sweating can be nervous system overload. Stress is caused by a multitude of things; if we are regularly stressed daily out the nervous system suffers. Reducing your workload is the best way to tackle nervous system overload, but if that isn’t possible identify healthy coping mechanisms—take up a sport, a hobby, or meditation as a way to de-stress, or talk with a therapist to help you put things in perspective.

Some mindfulness practices can be helpful—meditation, yoga, breathing exercises. Another thing to try is physical exercise. It decreases stress and strengthens the nervous system. Find what works for you and then stick to it.

If your sweating suddenly increases, for example you wake up drenched in sweat in the middle of the night for days at a time, you may have an underlying health condition that needs to be addressed.

  • Infections such as the flu or common cold, are among the more common culprits. In this case sweating is usually accompanied by other symptoms—fever, headache, runny nose, cough—which will resolve in a few days.
  • If sweating is a symptom of heart problems, it is usually accompanied by fatigue and swelling of the feet and legs. These symptoms tend to get worse if exposed to heat.
  • Hyperthyroidism—increased metabolism due to a hormonal imbalance—can result in higher body temperature, a higher resting heart rate, sweaty palms, and weight loss.
  • Sweating may be a symptom of diabetes or some diabetes medications that quickly lower blood sugar levels.
  • Heavy sweating can be an indication of a malignant tumour if accompanied by a mild fever, loss of appetite, and weight loss.
  • People who suffer from a lung disease also sweat more heavily; this is often accompanied by extreme weight loss.

Most of these conditions develop slowly. Be alert to changes in your body. If you are unsure what is causing them, it’s important to seek medical advice.


Sometimes people who are otherwise completely healthy sweat excessively. This is a condition called primary focal hyperhidrosis, which affects about 1% to 3% of the population, and usually starts in childhood or adolescence.

It’s called focal (or localized) because it only affects specific parts of the body, such as the underarms, groin, head, face, hands, or feet. Symptoms tend to occur on both sides of the body equally.

We don’t yet know what causes primary focal hyperhidrosis, but it seems to stem from a minor malfunction in the nervous system. There is some evidence that it could be genetic.

While the condition isn’t dangerous, it can cause embarrassment and even self-induced social isolation. Finding ways to manage the condition can make a world of difference to your mental health.

Managing your sweat

  • Drink more! When we sweat, not only does percentage of plasma in our blood drop causing the heart to work harder to pump blood, we also lose the salts and minerals necessary for our bodies to function well. When we sweat more than usual, we need to compensate for lost fluids and electrolytes.
  • Respect your personal hygiene—wash regularly, rinse your body more often when it is hot. If your clothes are sweaty, change them.
  • Some fabrics either increase sweat production or intensify odours. Choose clothes that ‘breathe’ or that ‘wick away’ moisture when you work out.
  • Use an antiperspirant/deodorant to reduce sweating/odour. However, these products can have negative side effects so are not recommended for daily use.
  • Use a deodorant alternative—there are many—but it might take some trial and error before you find what works for you.
  • If excess sweating is accompanied by other suspicious symptoms (weight loss, weakness, etc.) talk to your doctor and find out what’s going on. You’ll be glad you did.

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