Sled dogs will run nearly 1,000 miles in the Iditarod. Watch what keeps them going.

The 2018 Iditarod Trail Dog Sled race officially kicked off on March 3 in Alaska. Mushers and their sled dogs are now racing nearly 1,000 miles from Anchorage to the finish line in Nome, a trip that typically takes anywhere from nine to 12 days.

The journey through the Alaska wilderness is trying for everyone involved. And as Alaska Public Media explains in this great video from 2016, sled dogs are not your average dogs. They’re super athletes trained to run thousands of miles.

But winning isn’t just about speed. What and how often the dogs eat also makes a difference. Take a closer look at how the sled dogs keep up their energy:

“As we all know, to have a great athletic performance, you need the genetics to meet the condition and you need nutrition,” says Dr. Stuart Nelson, the chief veterinarian of the Iditarod, in the video.

Nelson explains that sled dogs consume an estimated 10,000 to 12,000 calories per day. What’s the human equivalent? Eating about 30,000 calories per day, or about 50 Big Macs.