Re: My 28 day challenge.
The advice I would give someone who has fallen off the paleo-wagon would be:
EAT MORE FAT.
Make sure you're eating a good amount of nuts for snacks (I eat 1-1.5oz of almonds a day, split between 2 snacks usually...with some fruit). Use butter/oil on veggies, eat the fat on meat when you can find organic/grassfed/pasture-fed stuff.
This will keep you from being hungry. You shouldn't be starving on this plan.