How were they supposed to work, and did they?
I’ve only seen them in old movies (30s and 40s).
A person would get inside a box with only his/her head sticking out, and turn on the heat.
Was the idea that heat would “burn up” fat?
When did they go out of style?
I think the way they worked was not by burning off fat but by sweating off fluid – the same way most body wraps work. Not a very healthy practice, but a lot of people do it. The idea has never really gone out of style; it’s just become a little more advanced in the way it’s done.
“There are more things you don’t know than there are things that I do know. I despair of the imbalance.” – Dr. Morgenes, The Dragonbone Chair
What about those shaky-belt things? The one you wrap around your waist that’s attached to a motor.
Is that supposed to loosen the fat or something?
Gypsy: Tom, I don’t get you.
Tom Servo: Nobody does. I’m the wind, baby.
Alpha, I’ve been wondering that since we found a fully working model in the storage room of our apartment. The belt was labeled, “strap me on, baby”. Anyways, since then, I’ve been curious as to the way these things allegedly “work”.
One minor usage note, if you typically keep a rigid death grip on your beer, it will tend to vibrate out of the cup when you use the device.
stoli
Well, blessed is just about everyone
with a vested interest in the status quo,
as far as I can tell.
You should get one of the newer treadmills with cupholders. It’s such a relief to not have my margaritas slosh out of the glass when I work out anymore. 
“I don’t know…I don’t know.” – St. DooDah