No they don't. And they hurt like a bitch!! Annoying as hell!!! zap zap zap!! Ouch! My friend gave it to me, because it was a piece of junk. I saw a video of a larger woman trying one and she actually was electrocuted because it malfunctioned, you should have seen her hop to get outta that sucker!
If you're talking about those belts that are supposed to shock your abs into a six pack then no. People are so desperate for an easy way to get a flat stomach, but there isn't one. It takes hard work and determination.