I have had my portable sauna for over a year and love it. For me, I have found I need to either exercise before I get in the sauna or take a hot shower in order to sweat, especially if I drink something cold before going in. (that lowers the core body temp. and makes the heart have to work harder in order to sweat). Anyway, it's importantant to take a shower right after in order to wash away the toxic sweat. Putting a towel on your chair is a wise choice and naked or wearing a towel is good too to soak up some of the toxins. It's very important to be hydrated before you go in and drink a large glass of water afterwards and take Vit. C Also, taking some extra sea salt (1/4 t.in your water) will help replenish the salt you lost in sweat. I haven't had any problems with the eating before or after. I usually stay in almost an hour (it takes me a while to start sweating) but if you start sweating right away you'll be getting rid of more liquid and need to replenish it before you get out. You don't want to dehydrate yourself. I'm learing that it is very healthy to alternate hot and cold (not icy) showers (the cold last).
The sauna really helps a person stay healthy, especially if they also eat healthy and exercise too. Hope this information helps you.