Hi hun, not really sure what you mean by something bad. The main problem is that if you start eating you could find it very difficult to get back on the plan.
If you do decide to just eat one meal, Xmas dinner then it is really important that you keep the carbs low, meat with a bit of veg no potatoes. If you don't then you will just put on a lot of whatever you have lost by then, altho it will be fluid rather than fat.
I would discuss with your pharmacist and see what they advise. Good luck whatever you decide x