Updated: May 16, 2020
Sweat is made up primarily of water (H₂0) and salt (Na+). This is why sufficient hydration is utterly crucial, so your body has what it needs to cool itself down.
Two different types of sweat glands
Sweat glands are small tubular structures of the skin that produce sweat. Generally, there are two main ones:
Eccrine glands generate most of our sweat. This watery sweat is responsible for cooling us down when the body temperature rises. Sweat that eccrine glands produce doesn’t taste like water because it also consists of salt, protein, urea, and ammonia. These glands are found all over the body, but mostly concentrated on the forehead, armpits, palms, and soles. As they are found directly on the skin surface, this allows the sweat to evaporate and cause the body's cooling effect.
Apocrine glands, on the other hand, are larger. They’re mostly located on the armpits, groin, and breast area. Since they’re close to hair follicles, they tend to smell bad. These sweat glands are mostly activated when we experience stress, anxiety and hormonal fluctuations.This is why we usually say 'stress sweat' smells worse than sweat released when we perform physical activity.
'Sweat is just fat crying'
How much we sweat during a workout is determined by a number of different factors, like age (younger people sweat more than older people), and gender (men tend to sweat more than women) as well as temperature, genetics, and humidity.
Another interesting factor is your fitness level. Surprisingly, fit people sweat sooner during a workout and more than those who are less fit. One research found that as your fitness level rises, your body's heat-regulating system becomes better, cooling you down faster when you need it and supporting you to train harder.
Don't be cheated by the loss of a few grams of body weight after an intense workout. This is simply water weight that you attain back when you rehydrate and doesn't undoubtedly mean you've burned lots of calories.
On the other side, don't presume that a low-sweat training means you aren't training hard enough or melting enough calories. It could be that your sweat evaporates fast because you're working out in air-conditioned space, near a fan or outdoors on a windy day.
If you are about to workout dehydrated - which indicates you didn't drink enough before a training - besides your body not being able to cool itself down and regulate its temperature properly, you are most likely not going to feel prepared for a workout. And, the same goes for restoring lost fluid after a workout. If you don't correct your sweat loss with enough water intake, especially for those of us engaged with hardcore training, we can become 'hypohydrated' and increase our overall body temperature. Remember: sweat is water and salt, so you’ll need to hydrate accordingly - with water as well as salt.
Choose your gear wisely
The most important thing to think of when it comes to your workout gear is breathability. You’ll be better off training in breathable and moisture-wicking clothes, and using a moisture absorbing gym towel.