If you are having doubts about the safety of the safety of the flex belt then please shed all doubts because the FDA has also finally approved of the flex belt technology with a few suggestions for the users. It says that it is entirely safe to use and can lead to improvement in the abdominal muscle structure. However, it also says that the increase is only minute and not enough to produce six packs. As far as the EMS technology in use here, there is no danger of it harming the muscles in the abdomen since it uses rapid contraction and expansion in the minuscule level to promote this kind of muscle growth.
The only doubt with this device is just how effective it actually is. For example, some studies have shown it to produce abs only if used in conjunction with regular intensive training and gym workouts. However, on its own it can only reduce fat deposits in the body.