I'm eating christmas eve and christmas day. I'm having a bit of everything, and the consequences of that will be dipping out of ketosis, gaining a few pounds, and having some hunger whilst I get back into ketosis on the 27th/28th etc. Its a rational decision I've made, as this is not the first time I've done sole source (recently had a baby and am losing a few pregnacy pounds) and I know from experience I dont have trouble getting back on. It will see me a few pounds behind target but I'm not in that much of a hurry and plan on then doing sole source with no exceptions throughout that boring January/Feburary time when nobody does anything which should see me pretty much at goal.
It is hard knowing I'm eating in 2 days though...a cube of irish stew sort of fell into my mouth before. Not that that will have me out of ketosis - but it just goes to show how a couple of days CAN weaken your resolve and how its often better just to decide not to eat, and even if you change your mind on the day, you haven't extended your one day into 5, by just knowing its ahead of you. Does that make sense?
Having said that I feel my decision to eat is right for me and my circumstances this year.