F1 drivers are weighed after a race primarily for two reasons: to monitor their weight loss due to intense dehydration and to ensure compliance with the minimum combined weight rules of driver plus car. Drivers can lose around 2 to 4 kilograms (4.4 to 9 pounds) during a race because of extreme heat inside the cockpit and physical exertion, which causes heavy sweating. This weight loss is significant enough that teams and medical staff track it to manage driver health and recovery appropriately. Additionally, since the minimum weight of the car includes the driver, drivers must meet a minimum weight limit (around 80-82 kg with all gear). If a driver weighs less, ballast is added to the car to reach the minimum weight to avoid penalties. The weigh-in after the race ensures these rules are followed and the driver's health can be assessed.