After the season of the glutton, loosening all restraint, when I got back to Japan I decided it was time to diet and exercise. I wanted to dump 10% of my weighty and go below the LT average. As it was winter I go to the sento 2X a week. Not part of the program but they have a reliable set of scales. At these old sentos (bath houses) they usually have 3 hot (42-44 C) baths and a cool off (18 C) bath. The sento I go to has digital scales and I have noticed the very curious thing, that in about 20 minutes you dump 0.5 KG (I am 60 kg) and I am pretty certain it is not from sweat (it would be ½ a litre!). I don't have a biological/medical background but usually you can tell if you have sweated a lot/dehydrated because of course you get thirsty and your urine changes colour. You need to replace the fluid. But after a sento this is not happening in a serious way so I am lead to think it is some other kind of energy transformation happening.

I know it probably all returns by breakfast time. Not interested in it as a way to lose weight ....just interested in the cause.

Also there is a big concern that if it is perspiration, perhaps these bathes are filling with sweat? Could this be true? Simple arithmetic: 20 people, 3 baths, 30 minutes a time, amounts to >7 litres of sweat going into each of the 3 hot baths every hour. They appear very clean. Any ideas?