I know, I know. Just one?
It may not sound like a lot, but consider that these holiday pounds are usually not lost once the New Year begins -- or ever, for that matter.
You can see, then, how someone can gain ten pounds in the course of a decade simply by being careless over a five-week period -- even if they are on top of their game the other 47 weeks!
Some studies have also found that people who are already overweight tend to put on an additional pound during the holidays.
I would be interested in seeing this same study done in countries where the holidays take place during the Summer months (i.e.: anywhere south of the Equator,) where rich, high-calorie foods aren't as weather appropriate.