Public health expert Nathan Grills of Monash University in Australia says the beloved Christmas icon should ditch his sleigh and start biking or walking to lose his jelly belly.
Grills' light-hearted research was published online Thursday in the annual Christmas issue of the British medical journal BMJ.
After conducting a literature review, Grills identified a "very high Santa awareness" among children. He determined that Santa made a reckless role model, noting his frequent cookie snacks, occasional cigars and refusal to don a helmet during "extreme sports such as roof surfing and chimney jumping."
"Santa is a late adopter of evidence-based behavior change and continues to sport a rotund, sedentary image," Grills wrote.
He also found a correlation between countries that celebrate Santa and large numbers of fat children.
"Santa promotes a message that obesity is synonymous with cheerfulness and joviality," Grills wrote. He suggested that jolly old Saint Nick should swap his traditional snacks of cookies and milk in favor of sharing carrots with Rudolph.
More disturbingly, Grills said Santa's close-up contact with sniffling, coughing kids made him a one-man outbreak waiting to happen, with swine flu the biggest seasonal concern.
"Unsuspecting little Johnny gets to sit on Santa's lap, but as well as his present, he gets H1N1 influenza," Grills warned.
Grills said he donned a Santa suit himself - and deemed the experience a public health nightmare. "I was kissed and hugged by snotty-nosed kids at each performance and was never offered alcohol swabs to wipe my rosy cheeks between clients," he wrote.