From zombies I've seen, they are after brains... so, if you went for the runts of the litter, you'd have to feast on many a stupid creature to match up to one big hefty hunk of good brain.
And besides... zombie brain isn't as tasty for the very reason that they died and all...
Personally, I go after computer nerds... they're either too fat to run away, or too lanky to take a good whop to the head.