Sweating is the body's normal response to overheating. The sweat cools the body by releasing a salty liquid through the sweat glands. There is no direct correlation between the amount of muscle or fat you have, and the amount you sweat, although the heavier you are the more you typically sweat. There are other factors that contribute to the amount you sweat, and sweating a lot when exercising usually means you are physically fit.
Sweat is produced as a result of the body creating heat. When the core temperature of the body reaches a certain level, the brain signals the body to activate the sweat glands, which release sweat onto the surface of the skin to cool the body. How much you sweat depends on how many sweat glands you have. Some people naturally sweat more than others. Other factors, such as high temperature, nervousness and exercise also contribute to the amount of sweat produced.
Muscle and Fat
The amount of muscle and fat you have are only factors when they contribute to your overall weight and overall fitness. People who weigh more have more body mass that needs cooling, and they use more energy to do certain tasks, so they build sweat more profusely and more quickly than someone who is thinner. Very fit people, who have more lean muscle than fat typically, sweat more because their bodies are more efficient at cooling down. According to the American Council on Exercise, this is because the body adapts to consistent exercise training by being able to sweat more and sweat sooner, so the body doesn't overheat.
Although muscle doesn't make you sweat more than fat, a pound of muscle will burn more calories than a pound of fat. According to genetics and obesity researcher Professor Claude Bouchard, a pound of fat burns about two calories, whereas a pound of muscle burns about six calories. Exercise will drive that number up slightly, as well. Even though muscle burns more energy, the difference in calories alone between muscle and fat is not enough to drive up the amount of sweat significantly.
If you are frequently sweating excessively, even when not involved in activity, and it is enough to soak through your clothes, you may have a condition known as hyperhydrosis, according to Medline Plus. Other symptoms include abnormally excessive and bothersome perspiration on your feet, underarms, head or face, and a clammy feeling or dripping of sweat droplets on the palms or soles of the feet. If the situation persists and disrupts your daily routines, consult a doctor.