Rockville native Helen Maroulis has changed her approach to wrestling in order to compete at a lower weight class and qualify for the Rio Olympics. (Jonathan Newton/The Washington Post)

Something comes over Helen Maroulis when she steps on the mat. It’s been happening since she was 7 — Maroulis wrestled against the boys back then — and nowadays there’s just no controlling it.

“It’s so hard to describe,” she says. “I feel like when I get my hair braided and I put a singlet on, I enter this zone.”

That’s the easy part. By now, wrestling is second nature for the 24-year-old Rockville native. She’s a defending world champion and hasn’t lost an international match in over a year. It’s the long stretches between tournaments and training sessions that are most challenging. Maroulis has no choice but to be obsessive about her diet. An extra pound or two could spoil everything.

Maroulis heads to the U.S. wrestling trials this weekend in Iowa City, hoping to earn a spot on the Olympic team. She’ll be wrestling for the first time at 53 kilograms (116 pounds). She’s spent more than a year preparing her body for the challenge. Maroulis walks around closer to 130 pounds and has spent nearly her entire wrestling career at 1211/2 pounds (55 kilograms). What difference does a few pounds make? In a word, everything.

“For me, the hardest part was the diet,” she said. “I love wrestling, love running, love lifting. But the diet was really hard.”

Women’s freestyle was added to the Olympic slate at the 2004 Summer Games with four weight classes: 48, 55, 63 and 72 kilograms. Despite being a heavy favorite, Maroulis missed a spot on the U.S. team by just a single point at the 2012 trials. Leading up to the Rio Games, the sport’s governing body reshuffled the deck, adding two weight classes but dropping Maroulis’s. To pursue her Olympic dream, Maroulis had to choose between moving up or down in weight.

She’d found much success at 55 — her trophy case includes hardware from three world championships: a silver in 2012, bronze in 2014 and last year’s gold — but Maroulis begrudgingly opted to drop to 53, rousing fears, stressors and self-doubt as crippling as anything she faced on the mat.

When she met Erik Arevalo, a personal trainer and MMA fighter, at a wrestling event, she explained that she’d spent weeks at Barnes & Noble studying diet books. “Everything is contradicting,” she explained. “This one says Paleo, this says high-carb, this says no carb, this says hormone diet. I was overwhelmed.”

He told her there was a healthy way to cut weight and agreed to serve as Maroulis’s nutritional adviser. She also teamed up with Charles Poliquin, an accomplished strength coach who has worked with a variety of athletes in all realms of sport. “My philosophy is simple,” he said. “This sounds stupid, but I want the wrestler to worry about wrestling. That’s it.”

To get her body ready for the lighter weight, he used the analogy of taking a car off the street and preparing it for a high-level race. “The first thing is empty out all stuff in the trunk,” he said, “and get rid of backseats, too. You want to make it as light as possible, which means getting rid of fat.”

The key, Poliquin said, was not sacrificing any of the motor — the muscle — in that process, which meant they had to be methodical, patient and smart. Poliquin wanted to start with data. He’d created a measurement technique called BioPrint, in which he measures fat at 14 points on the body, from chin to stomach to calves. He tries to analyze where fat is being stored and why it won’t come off. In addition to the calipers’ reading, he studies blood tests, hormone levels and sleep patterns. Maroulis’s initial reading: 23.9 percent body fat.

Poliquin ran this test weekly and adjusted the workout plan whenever the numbers changed. By January, she got the figure down to 16 percent and will enter this weekend’s trials at 12 percent body fat. If she can qualify, she hopes to compete in Rio around 9 percent.

“She’s just a really, really hard worker,” Poliquin says. “Too much sometimes. Sometimes we have to hold her back.”

Maroulis consults with Arevalo daily. He stresses to her that every calorie has to be earned in the gym and there was no room for excess. “We needed to protect her strength and make sure she still felt good on the mat,” he said.

The wrestler shares her training schedule with Arevalo each week, and he’ll tailor a plan for each day based on the effort and workload required. He’ll prescribe different levels of carbohydrates, proteins or macronutrients that will help sustain her through a workout or to properly recover from one.

“Once she stopped trying to figure everything out and just trusted the process and saw it made sense, it worked,” he said. “The hardest thing for her to understand was the results aren’t all coming during work; they’re coming during the rest. So incorporating more rest, getting better sleep — it allowed her to relax, cortisol levels drop, stress levels drop and the weight started coming off.”

“It wasn’t really natural to my personality,” she said, “to just wake up and have to plan out every meal, every calorie, how many carbs do I get?”

Change didn’t come overnight. In January, Maroulis won a wrestle-off match that earned her a spot in the Pan American Olympic Games Qualifying Tournament, one of the top events on the American calendar. But she decided to bow out of that qualifier because she still didn’t feel comfortable at 116.

Her coaches told her to take a few days, not worry about weight or even wrestling. When she stepped on a scale, it read 140, and Maroulis was in tears. But she managed to drop 13 pounds in just a couple of weeks and was quickly back on track.

Skipping that event, though, meant the United States still hasn’t qualified for an Olympic spot in the 53-kilogram weight class. Even if Maroulis wins this weekend in Iowa, the Americans need to fare well either at a tournament in Mongolia from April 22-24 or one in Turkey next month to punch her ticket to Rio.

Maroulis says she’s feeling comfortable with her body heading into the trials, and Poliquin is convinced his student is competing with the strength of a wrestler two weight classes above her. When she began working with Poliquin, Maroulis says she couldn’t do a single pull-up. She can now do pull-ups with 60 pounds of weight strapped to her waist.

All the work away from the mat means that Maroulis can focus her energies on the one thing that’s always felt the most natural: wrestling. She’s come to terms with her body type, her size and her strength. She knows her limitations and her capabilities more intimately than she ever could’ve imagined four years ago.

“Wrestling has taught me it’s not what my body looks like,” she says, “but what my body can do.”