actually yes they do work. pretty well. but like anything, its not magic. 45 minutes with the ab belt on is comparable to 30-45 minutes of light ab work. ive only used one a couple times, a dude at the gym has one he let me use. he likes to wear it while he takes walks. makes sense. my ex gf just got one too, and she loves it. but they are pricey, and like i said.. u cud get the same by just doing ab work. so for me its not worth it, but if i had one id definitely use it.