The average person loses 1 kg of weight during sleep through breathing and sweating

People lose weight during sleep through respiration (breathing) and perspiration (sweating). It’s estimated that during sleep, we lose 1.9 grams of weight per minute, which amounts to nearly 1 kilogram of weight per 8 hours of sleep. Most of the weight we lose during sleep is water weight that escapes our system.

Each time we exhale we lose a little bit of water. It’s easy to check – breath on a cool piece of glass and you will see some moisture.