This is a question I'm still trying to get to the bottom of, but these are the results of my current research:
Baby(11 lbs)--3 small beads (possibly less would still work)
Toddler (24 lbs) 6 beads (possibly less would still work)
Me, (small woman) 6 beads(like a bracelet) got it, but more worked better.
I am guessing that men will need more, but my research isn't complete yet.