I feel extremely thirsty sometimes although I keep drinking water throughout the day. I drink about 2-2.5 litres of water everyday. It is fine during daytime. By the evening it feels like I have not drank water since long even after just having a glass of water. It gets so severe at times that it becomes difficult to sleep at night. I keep getting up to drink water and still end up feeling thirsty. I have been facing this for almost 6 months. I drink warm water. I have also lost weight in the past year without particularly working out.