GREEN BAY – The first sign was the sluggishness. At the time, Ahmad Thomas didn't understand it. Seemingly out of nowhere, he'd wake up and feel lethargic even after a full night's rest.

There weren't many answers for what ailed him back then. Adopted when he was only three months old, Thomas grew up without much of his family history or medical background.

Battling through the discomfort, Thomas developed into a major Division I football recruit coming out of Miami (Fla.) Central High School in 2013. He had more than two dozen scholarship offers, including one to play linebacker at the University of Miami, before committing to play at Oklahoma.

Recruited as an athlete, there was a long discussion on campus about whether Thomas would play safety or linebacker for the Sooners. His high school position coach, former Raiders safety Derrick Gibson, wanted Thomas to play linebacker, but safety eventually prevailed.

It was hard to argue with the production. While he had to closely monitor his weight to play the position, Thomas became a three-year starter at Oklahoma, recording 149 tackles, four interceptions and 2½ sacks in 51 career games.

Yet, it wasn't until Thomas participated in the Los Angeles Chargers' rookie orientation camp last year he began to better understand his body.

During his physical, Thomas was diagnosed with anemia, a condition where a lack of sufficient red blood cells prevents oxygen from properly transmitting to the body tissue. The most common symptom? Fatigue.

While Thomas trusted the diagnosis doctors gave him, an inquisitive mind led him to take things one step further. Through some prompting from his wife, his adoption papers, and the magic of Google, Thomas tracked down his birth parents.

In a conversation with his biological mother, Michelle Hooshing, Thomas' eyes were opened to everything, including the heart murmur he was diagnosed with in high school.

"I was talking to her about it and she was telling me where all these things originated from throughout the timeline of my family," Thomas said. "I learned a lot about myself. I'm still learning a lot about myself."

With a better grasp of his medical history, Thomas got another chance to live his NFL dream when the Packers brought him in for a workout last November. Unlike his previous visits, Green Bay wanted him to try him at inside linebacker.

Making the rounds as a 214-pound safety at the time, Thomas showed enough in the workout for the Packers to sign him to their practice squad on Nov. 29. He finished the season there, learning the nuts and bolts of his new position.

"I felt like that was a blessing that I received because it had been a long year for me," Thomas said. "I finally got here, took the opportunity and rolled with it. I just wanted to learn as soon as I could. My plan here was to learn the defense as fast as I can."

One other area of his anatomy Thomas gained a better understanding of through a slew of medical tests was an irregular stomach condition, which resulted in frequent bouts with reflux.

Doctors wondered if it might have been due to a bacterial infection of some sort, but that didn't make sense to Thomas. An admitted "OCD clean freak," Thomas keeps a tidy house and won't eat anything without washing his hands first.

Finally, Thomas got his answer.

"Basically my stomach is like if you squeeze a water balloon in the middle," said Thomas, touching his index finger and thumb together to illustrate the narrow space. "That's how it is."

With all this new information in the wake of his anemia diagnosis and personal epiphany, Thomas made the decision after the 2017 season to become a vegetarian.

While Thomas didn't know of any vegetarians currently playing in the NFL, he discovered former Arizona defensive end David Carter became a vegan during his career to combat tendinitis.

Thomas immediately felt the benefits of a plant-based diet, which improved his digestion and reduced stomach inflammation since his body no longer was processing more difficult-to-digest red meat. Cognizant of maintaining a well-balanced diet with fiber- and iron-rich foods, Thomas began to enjoy a more restful sleep.

The trickiest part for Thomas was he also needed to put on weight this offseason to complete his transition to linebacker. Historically, that's never been an issue for Thomas, who weighed as much as 227 pounds at Oklahoma.

Staying in Green Bay for the entire offseason, Thomas put together a plan with Packers director of performance nutrition Adam Korzun to help make it happen.

"I told him about the decision I wanted to make without eating meat, so he just got me on the plan," Thomas said. "There's a lot of vegetarian burgers back there, a lot of vegetarian food. They have what I eat prepared for me, and I go pick it up and eat it."

At night, Thomas would carbo-load to prepare his body for morning workouts. Steering clear of most sugary fruits, he drank vegan protein shakes and filled his lunch and dinner plate with as many vegetables as it would hold.

His adopted mom, Marvice Thomas, often asked Ahmad how he does it. "Health is wealth to me," Thomas said. "I'm not easily influenced when it isn't something I stand for."

Thomas hit his target, reporting to camp looking like the 232-pound inside linebacker who ate the former four-star recruit. He still leans heavily on that past experience as a safety, though.

This summer, it's helped Thomas make a run at a roster spot as coverage linebacker in Green Bay's sub-packages. In three preseason games, he's registered eight tackles and a deflection.

"He's an explosive athlete and I think that's what you need in the National Football League to play defense," defensive coordinator Mike Pettine said. "You're seeing the college spread, the one-back run game, where you have to have guys that are less playing downhill and more playing side to side, and the ability to cover people whether it's out in space or tight ends man-to-man or backs man-to-man as those players are getting more athletic. And defensively, you have to act accordingly.

"I think he's kind of the perfect example of guys you're looking for – that hybrid type."

With his new diet, Thomas no longer struggles with the sluggish mornings and that's provided him a peace of mind that goes well beyond what he's feeling physically.

It's removed the worry from football for Thomas, who is taking a similar approach into Thursday's preseason finale against Kansas City on the eve of this weekend's looming roster cuts.

"Every game is just like my first or my last. You never know," Thomas said. "I'm focusing in and doing what I'm supposed to do, like I've been the whole camp. I can control what I do out on the field. I can't control what goes on up in the office. My main focus is to do what I'm supposed to do."