It’s lunchtime at the Caratunk Hostel, located just shy of Maine’s 100 Mile Wilderness. Appalachian Trail thru-hikers pour in, half-starved. Hostel owner Paul Fuller hands out his legendary pulled-pork sandwiches and thick milkshakes. The hikers come back for seconds, thirds, and fourths, ignoring the plate of cucumbers and cantaloupe Fuller keeps hawking.

“I’m constantly trying to get fruit and veggies into these guys,” says Fuller. “But it’s always the last to go.”

An avid hiker himself, Fuller has learned thru-hikers’ common preferences over the years. His hostel has become an oasis on this section of the trail, which is short on grocery and convenience stores. The hostel store carries all the backpacker favorites: Pop-Tarts, instant mashed potatoes, energy bars, and luxury items like dried mushrooms and cherries.

We hung out at the hostel on a recent Saturday to see how thru-hikers were fueling their attempt on the 2,200-mile trail. The northbound hikers we met here had been at it for months, and the southbounders were just getting going, but both were finding it hard to stay fed. Hikers regularly spend eight or even ten hours on steep and rocky terrain each day to get in their miles, burning somewhere around 4,000 calories a day.

How well are they doing? We asked Anne L’Heureux, a registered dietitian and an endurance athlete who counsels hikers on nutrition, to weigh in on their choices and offer the rest of us some practical tips for getting down the trail, which starts with eating food that helps the body fuel and recover, packs easily, and tastes good.