How can people avoid the holiday weight creep? 

Set up boundaries; try to stick to your year round healthy routine of regular exercise and healthy meals throughout the holiday season. Allow your self-moderate indulgences only when you are at events. Remain hydrated; hydration can be a major concern during winter months since you do not get as thirsty. I recommend drinking alkaline hydroxide water; this increases hydration while reducing inflammation from the holiday food you do consume.
What are some healthy but tasteful alternatives to traditional healthy fares?

• Avoid processed foods altogether, and fill your plate of up the protein and vegetable options and only a small serving of the indulgences like the starchy stuffing casserole, or the candied yams, bread, pies, cookies, etc.

• When baking consider using coconut sugar, pure maple syrup, local honey, ground flax seed, dark chocolate, or almond flour instead of the enriched processed flours and sugars.

• Instead of making starchy vegetable casseroles consider roasting your vegetables with herbs and coconut or olive oil. They will retain their nutritional value and will still taste great.

If people do succumb to poor eating habits, how can they get back on track?

They do not allow their mind to throw in the towel and surrender their bad habits to the entire holiday season. One night of indulging is better then weeks of being off the healthy bandwagon. Do not beat yourself up for having your favorite holiday foods, just get right back on track and stay active and hydrated.