When I’m at the gym or out for a run, I find the presence of sweat a strong indication of a successful workout. If I’m not drenched in sweat, then I think I didn’t work out hard enough. This is a common misconception many of us have.
I can’t even count the number of times I have been told by coaches, my parents, or sporting brand ads that in order to shed calories or fat or even gain muscle, you need to sweat after every workout. It sounds almost intuitive: you must be working harder than normal to sweat, which means that the more you sweat the more you’re burning.
On the contrary, almost all research done on sweating comes back with the same conclusion: a correlation between sweat and fat burn does not exist. So where does this myth stem from?
Our muscles do require a certain amount of calories, or energy, in the form of fat or carbohydrates. The harder we work out, the more energy we need. At certain energy levels, our body will need to work harder, which in turn will raise our bodies’ overall temperature and trigger a response from our sweat glands.
Sweating is an autonomic nervous system function that is triggered when your inner core temperature gets too high. Sweat is our bodies’ way of cooling off and maintaining a normal body temperature. Not only does sweat cool the skin as it evaporates, it also helps cool our inside core temperature.
Made up of water, sodium, and other substances, sweat helps cool your body. It makes sense to think that since working out increases our inner core temperature, the amount of sweat we produce is a good indication of how hard we work. As you work out harder, your body needs to pump more blood to your muscles, which logically increases the body’s overall temperature.
However, despite people having an average of 2–4 million sweat glands in their body, no two people produce the same quantity of sweat — especially not for the same activities.
Everything from gender, genetics, environmental conditions, age, weight and even fitness can drastically change how much a person sweats. Aspects like stress, anxiety, and hormones also trigger the stimulation of those sweat glands and have been shown to even alter a person’s body temperature.
Therefore, it is a major misconception to believe that the rate you sweat is only determined by fitness level.
Fit people do sweat earlier and more easily than most people. Individuals who are fit have bodies that are more efficient at not only sending motor and neuron signals to their muscles, but also are more effective at regulating the inner core temperature. As a result, individuals who are fit sweat much sooner, cooling down their bodies faster and for prolonged periods of time, to allow those individuals to work out longer.
Another potential explanation for the sweat-fitness correlation myth could originate from the fact that a prolonged amount of sweating does make you lose water weight, since your body is producing so much sweat from your glands. You could appear to have burned fat and calories when in actuality you have only burned off water weight.
In other words, your rate of sweat and level of calorie burn are not synonymous. You could be sweating more than another individual not necessarily because you’re working out harder, but more likely because of different factors like a higher weight or higher level of fitness. To more accurately keep track of fat or calorie burn, individuals should focus more on heart rates and scale numbers instead.