There is iron in our blood, which is magnetic. Roughly how strong would a magnet have to be to induce a noticeable attraction? It would be nice to know this for several distances. Also, do electromagnets that strong exist?
Humans are weakly diamagnetic. Rather than being attracted by a magnetic field we would tend to repel the lines of force.
Look at the work of the High Field Magnet Laboratory http://www.ru.nl/HFML/, in particular http://www.ru.nl/hfml/research/levitation/diamagnetic/ where they demonstrate levitation of a living frog. It took about 16T to levitate the frog.
Mainly the iron in the blood is incorporated with other components. In the blood, plasma may be those forces of attraction are a lot stronger than the forces of attraction between a magnet and a magnetic component. Well, if it comes to bonds, they are the strongest forces and I guess, that to have a magnet strong enough to attract a human, we will have to first break all the bonds between the haem and globin, and that's not easy at all
That is purely my guess!