F1 drivers typically lose around 2–3 kg (about 4–7 lb) of body weight over the course of a race, mostly through sweat and fluid loss. In especially hot and humid races (like Singapore or very hot events such as Qatar), reported losses can climb to around 4 kg, and some drivers like Lewis Hamilton have said that in extreme conditions they can lose close to 4.5 kg or about 10 lb in a single Grand Prix.