I have normal T3/T4 levels, but in the other thread I referred to how for my entire life I can tolerate very cold temperatures but not hot (most people consider moderate or warm) temperatures. I am male and have never smoked cigarettes in my life. I refer to the underweight as during my childhood, I had been ill often during childhood because I was always underweight since not only am I ectomorphic but I did not eat much. In this thread I refer to how during holiday I seem to eat much good food that is quite heavy with a lot of kilojoules (especially paella when I went to Spain last year ), but I lost 8 kg. So perhaps it was water loss because I perspired so profusely from the 25-35 C Madrid summer temperatures, which was extremely unpleasant. It was just alarming to return home and step on the scale to see I lost 8 kg in 6 days.