Russell Hornsby, David Giuntoli Russell Hornsby, David Giuntoli

When it comes to the world of Grimm, nothing is what it seems, and that applies to Grimms themselves.

Friday's episode (9/8c, NBC) picks up after Nick's (David Giuntoli) recovery from his zombie-like state. Of course, the outside world doesn't know that, so when he gets put through a physical that includes running to raise his heart rate, the results are somewhat surprising. "There are still some more changes [to come]. I go ashen from time to time," Giuntoli told reporters at a screening of "A Dish Best Served Cold" in October.

David Giuntoli's 5 tips to playing a Grimm zombie

The revealing scene also offers fans a glimpse of the Grimm's physique, which is usually well-covered to keep off the chill of Portland, Ore., where the series shoots. "That was the dreaded shirtless treadmill shot," he said, "I skipped eating." Giuntoli is joking, of course (we hope). The actor appreciates a good meal, and shooting in Portland offers no shortage of delectable markets and restaurants.

In fact, Friday's episode features the real-life Portland restaurant, the Raven & Rose, as seen in the clip with Monroe (Silas Weir Mitchell) and Rosalee (Bree Turner) below:

But what, if anything, does the episode have to do with cuisine? "Portland is the gastronome capital of the United States for gastrophiles, I suppose," Giuntoli tells "We do our best to incorporate the food culture of Portland with our Grimm-crazy story lines."

That story will involve the revival of an age-old Wesen feud, a serial killer and the Raven & Rose restaurant. But despite the culinary theme, Giuntoli would not recommend sitting down to dinner while watching. "I wouldn't eat," he says. "It's like public pool rules: Don't eat a half-hour before you watch Grimm and a half-hour later. Just hold off."

Check out this preview of "A Dish Best Served Cold" for more hints about the unappetizing story:

Grimm airs Fridays at 9/8c on NBC.