I think that depends on
a) How much running you're used to
b) How much barefoot walking/running you've done
c) Particularly if the answers to (a) and (b) are "not much"....How gradually you ramp up toward the barefoot 5K
I LOVE barefoot, but I've read so many accounts of people going from regular shoes to barefoot and trying to run too far too fast, resulting in injury. I spent 3 months walking/hiking in Vibrams before I started exercising in them and have avoided any injuries--in fact, my problematic knee has been trouble free since the switch.
Zone diet on and off for several years....worked, but too much focus on exact meal composition
Primal since July 2010...skinniest I've ever been and the least stressed about food