This may seem like kind of an odd topic but in my life I've noticed that eating foods when they are hot (temperature wise) has always made me feel worse than when eating it cold. For example, eating 3 slices of hot pizza vs 3 slices of cold pizza. I'm using pizza as an example cause a good number of people have eaten it hot and cold. When I eat it hot I feel like total crap but when I eat it cold I don't feel as weighed down and sluggish. This goes for almost any food.
I realize cooking has been around for a long time but it's still somewhat an invention so wouldn't heating up food be unnatural? Is it possible eating food that is heated is not as healthy as non-heated food? I felt the same way when I used to eat fried chicken.