“Sweating more during a workout means you're burning more fat.”
Strong confidence. Sweating primarily regulates body temperature. Sweat rate is strongly affected by environment, acclimation, clothing and individual physiology, and short-term weight loss from heavy sweating is mainly water that returns with rehydration.
More sweat does not mean more fat loss. A person can sweat heavily in a hot room with little exercise or sweat less during a demanding workout in cool conditions.
Exercise intensity and duration affect energy use, while sweating manages heat. They can rise together, but sweat itself is not evidence that body fat was burned.
Safety note: Heavy sweating can cause dehydration and electrolyte loss. Excessive fluid intake can also be dangerous, so avoid forcing enough fluid to gain weight during exercise.
Talk to a healthcare professional if: Seek urgent help for confusion, fainting, severe weakness, vomiting, hot dry skin or other possible heat-illness symptoms. Discuss unusually high or absent sweating with a clinician.
Do not judge workout quality by a soaked shirt or a temporary drop on the scale. Use performance, duration, perceived effort and progress over time.
Hydrate according to the conditions and your needs, and track training with measures that match your goal, such as pace, resistance, repetitions or perceived exertion.