GLENDALE, Ariz. -- There's a fad spreading through the NFL, and Arizona Cardinals running back David Johnson is among the latest to pick it up: a plant-based diet.

After watching two food documentaries on Netflix, Johnson and his wife, Meghan, both adopted a plant-based diet about a month ago. Thus far, according to Johnson, an All-Pro and Pro Bowl selection a year ago, he feels better since (mostly) removing meat from his diet.

But he's had to make slight alterations to his diet.

Johnson realized quickly as training camp began in late July that sticking with a strict plant-based diet caused him to lose more weight than he intended. He reported to training camp at 223 pounds, lighter than he had been in the past. His lower weight made him more agile, which Johnson said benefited him as a receiver, but he needed to maintain a certain weight to be effective, so he began adding meat in his meals.

By and large, he's cut most meat out of his diet and has noticed he has more energy and less fatigue.

"It wasn't as hard as I thought it would be," Johnson said. "I thought it would definitely be hard just because, as Americans, we're taught to eat a whole bunch of meat. It's not even just eating meat, it's the portions. What I've learned is that we're taught eating like 24 ounces of steak is a manly thing, when really you're only supposed to eat 8 to 10 as a portion."

Johnson changed his diet after watching two documentaries on Netflix: "What the Health" and "Forks Over Knives." Both films expound on the benefits and virtues of a plant-based diet, using support from research papers and experts. Those documentaries, plus their own research, led the Johnsons to make the switch.

"We just kind of both did it at the same time," David said.

Plant-based diets have spread throughout the NFL. Former Cardinals defensive tackle David Carter adopted a plant-based diet in 2014. According to the animal rights group PETA, at least five players have credited their switch to a plant-based lifestyle to seeing "What the Health." Among the current NFL players known to have converted to either a completely or partially plant-based diet are Green Bay Packers quarterback Aaron Rodgers and New England Patriots quarterback Tom Brady, according to PETA.

Cardinals safety Tyrann Mathieu began eating a plant-based diet last season and lost 16 pounds, but the difficulty of sticking to the restrictions during road trips caused him to begin eating meat again. He felt better with a plant-based diet, he said, and he might try it again after the season.

Johnson curbed any concern about maintaining his caloric intake by shrinking the size of his meals and increasing their frequency. He now eats about six small meals a day instead of the three or four he had when he wasn't following a plant-based diet. Between meals he snacks on nuts, mainly cashews.

"That's another way to get my calories," he said. "Some of that stuff also has protein in it."

Johnson's venture into the plant-based world given him a new perspective on meat and its effect on people. "We've learned that meat is bad for you," he said. "But it's really where you get the meat from and how much you eat of that meat in each sitting, because most Americans eat lunch, dinner, supper and it's always meat and it's always a huge portion. We're just learning about that stuff."