Santa better slim down because it's bad for the kids, an Australian research scientist writes in the annual Christmas issue of a British medical journal. The public health expert Nathan Grills even connected countries that celebrate Santa Claus to those with expanding populations of fat children. "Santa promotes a message that obesity is synonymous with cheerfulness and joviality," Grills writes. What's worse? Old St. Nick also encourages the spread of swine flu by getting little ones to sit on his lap, and he teaches reckless behavior with his "extreme sports such as roof surfing and chimney jumping."