Even Santa isn’t immune to Dr. Mehmet Oz’s take-no-prisoners attitude toward healthy living.

On Monday’s “Dr. Oz Show” (3 p.m./Ch. 5), Santa gets the once-over from the doc, who’s focusing on the “12 Healthy Days of Christmas” (with a tip a day on keeping fit).

During the show, Santa — who’s known to sport a big belly — comes out to have his waist measured by Dr. Oz, who then suggests some ways Mr. Claus can try to slim down. Monday’s show also features Oz kickin’ it up with the famed Radio City Rockettes (dancing — another way to burn calories).