not really sure what you mean, could you elaborate? I think it's more that the body conducts electricity, you can't use it as a source of electricity itself.
where the motion of the wearer uses kinetic energy to charges batteries. I think that probably addresses your problem of storing the energy. And then it can be used outside the body by using those batteries to power other things.
The nervous system is powered by electricity, but while it is enough to get muscle contracting (with all kinds of chemical help along the way) it's not enough to power stuff. But a result of all that movement is kinetic energy and heat which CAN be harvested.
Look into galvanic skin response and capacitive sensing tech, aka the skin's ability to conduct and touchscreens. Although a human body has a lot of resistance, it can be used to complete a circuit, easier to ground it than to power it.