I'm sure others have noticed this, but I don't see anywhere near as much weight loss when eating chicken, seafood or other meat compared to steak. Even with ground beef compared to ground turkey, I notice a difference. So, back to beef (steak at least two to three times a week) it is ; ) My wife says steak is a diuretic (has that affect on her) and that's why she likes to eat it several times a week.
For the record (in case anyone is interested), I'm down 30 lbs in two months and feel great eating Paleo. I just find the meat thing interesting (what stalls me vs what allows me to lose more weight). And while I'm big on beef (moreso steak) I only eat grassfed on occasion (cost/availability and I have a good butcher in my area where I get my beef regularly). I supplement Omega 3 because of this (thought I'd mention this).