you should wear it on a shirt...that way the shirt absorbs the sweat and your body doesn't try to re-absorb it.

Bare skin. Its meant to stop your skin from breathing therefore you sweat like crazy.

bARE SKIN

some people use saran wrap around their skin. ;)

im not sure but with common sense(no pun intended)
i would think on your bare skin because than it will bring friction and ....well you know the whole plastic bag theory
so yeah.

around skin

This isn't a good way to lose weight anyway. Look for better ways.

You are supposed to layer up as much as possible and put garbage bags over that.

You need to be careful doing that because you can easily become dehydrated.

Just wear sweats. Your skin needs to breathe. You cover up with plastic and you could end up in a hospital...or worse. It HAS happened.

Don't wear a plastic bag at all!

Your body sweats while you exercise so that the evaporating sweat will cool you down, if you stop it from evaporating you are in danger of overheating.

You body will sweat more to try and correct the overheating and you will loose water but this won't help you lose weight because the water will be replenished as soon as you have a drink.

If you want to lose weight try the old fashioned way of eating less and burning some more calories.

skin
wrap it so tight you will be all shiny and stuff when the light shine at you

When cutting weight with the plastics, you want to wear them over a couple layers of UnderArmour and under sweats. When I cut here's what I normally wear:

On top from first to last: Long Sleeve UA ColdGear mock, 2d long sleeve UA, short sleeve UA, sauna suit top, sweatshirt, pullover hoodie, zip up track jacket. Sometimes a second hoodie before the jacket if I'm in a hurry. Hoods up and tight.

On bottom: UA ColdGear leggings, Nike Running tights, sauna suit bottoms, tight sweatpants, track suit bottoms.

Two or three pairs of socks, always full-finger sports gloves, and beanie under the hoodie hoods, and often a facemask top off the ensemble.