"I don't eat gluten, I don't eat dairy, I don't eat sugar really, and the only thing I drink is water," the svelte Dancing with the Stars contestant, 39, recently told reporters backstage after a performance on ABC's hit show. "I eat really, really clean. I'm very strict."
Those might sound like minimal options for the pint-sized starlet, but they seem to fulfill her just fine.
"I eat a lot of food, but it's all brown rice and vegetables and lean meats and things like that," she explained.
Aside from her newfound ballroom hobby, McKellar, who has a 3½-year-old son Draco, relies primarily on her healthy eating habits as opposed to strenuous workouts.
"I don't do any kind of exercise regularly except for yoga and things that are slow and not cardio-based," she said.
But now in the thick of the dancing competition with partner Valentin Chmerkovskiy, she's been in for a rude awakening.
"I've been taking ice baths every single night," she said. "Hot shower, ice bath – I've been going back and forth between the two. It has made all the difference in the world. It has, like, seriously saved me. It's very unpleasant, but it's worth it."