The first thing I thought of was TOM as well... if, after a few mos you are sure it's not... please be sure though, try switching your diet for a few days or a week then go back to atkins. For example something like the Zone might help, or CAD.. or something which gives you some carbs but isn't like just giving up and falling off the wagon. I know every month without fail my energy, motivationan, and mood is zapped for a couple weeks when TOM rolls around. My perspective of what I want to eat changes too.

Good luck finding out what's going on!!
Meg