As alex_beecroft points out in the next comment, technically there's a certain element of starvation going on. What more fundamental vulnerability could there be?

And of course just not being so well padded is in some ways more dangerous, I suppose--though I'd think my increasing ability to run (or at least ride my bike really fast) away from saber-toothed tigers would be offsetting that vulnerability to some extent.

Also, stringier meat.