Armed with his iPhone 6, Rich Bell has taken to narrating his Pokemon Go hunting practices on YouTube.

One of many devotees of the wildly popular augmented reality game, he gives weekly updates of the Pokemon he has caught, explaining where and how he captured the virtual creatures that appeared on the screen of his mobile device and led him on a foot chase around the Inner Harbor and other locations.

His updates also include information about an unexpected side effect of playing the game: the weight he's lost.

“I'm getting more active than ever before instead of sitting on my butt and playing Black Ops 3,” Bell said, referring to a military-themed video game. “I think it's made my overall mood a lot better, too. It's made me feel a lot more positive.”

For the record, Bell, 29, of Perry Hall, says he has lost 10 pounds since he started playing Pokemon Go last month.

Users of the location-based game that became a worldwide craze this summer say they've added dozens of miles of walking to their weekly routines. Some users have reported significant weight loss and a sunnier disposition as they get outside and socialize with other users.

Pokemon Go was released in the United States in early July by San Francisco-based Niantic Inc. The game requires users to walk around, using their smartphones or other mobile devices, and hunt for Pokemon, which are virtual pocket monsters. They visit PokeStops, landmarks where users can collect items they need in order to play. Because it uses GPS, the game knows when a player is close to a Pokemon, a Pokestop or a virtual Pokemon “gym.” It also works with a player's smartphone camera so that the virtual Pokemon appear to be standing on a street or in a park.

Players can walk to the virtual gyms and battle other Pokemon “trainers” or users. The game also requires players to walk to hatch virtual eggs, which can contain rare Pokemon that have different abilities and strengths.

Professors and researchers at the Johns Hopkins Bloomberg School of Public Health published an editorial in a campus publication this month speculating that Pokemon Go and other so-called augmented reality games could be “very useful” in encouraging young people to be more active.

“Maybe the secret sauce is not trying to be a healthy app, but instead focus on a game that gets people off the couch, into the real world, with inadvertent health effects,” the self-described Johns Hopkins Pokemon Preparedness Team wrote in Global Health Now, an online forum and newsletter. Their article is headlined “Pokémon GO! — Pandemic or Prescription? The Public Health Perspective.”

To be sure, the health benefits of Pokemon Go are so far largely anecdotal, but health care professionals are taking notice and are cautiously optimistic about what may still turn out to be a summer fad.

Yvette Rooks, an assistant professor of family and community medicine at the University of Maryland, Baltimore, said she's seen more than 30 young patients in recent weeks who have reported losing weight and playing Pokemon Go.

“We have become such a sedentary society,” she said. “We sit in front of computers — your whole world can be within inches of you. Now you have this new technology wave that gets people outside, in the sunlight, socializing, exercising. And they don't even know it.”

At a wedding she attended in California recently, Rooks said, the father of the groom was walking around and catching Pokemon during the reception. The elderly man told her he was finding it easier to climb stairs and that his belt was looser.

“I'm enthused about it,” Rooks said. “I may even do it. We'll see.”

Bell intends to keep playing and hopes to get into the 330-pound weight range soon. He also cut his daily soda habit. He said he walked about 40 miles in one week — much of it while playing Pokemon Go.

“I should have probably been exercising for a long time now,” Bell said in his first YouTube video. “I'm a big dude, I'm definitely overweight. Exercise should be a part of my life, I'm not gonna lie.”

Lacey Verger had fallen into a Netflix rut and was spending every evening on the couch watching films until Pokemon Go got her going. She lost 11 pounds in a few weeks by walking at least a mile and a half a day to play Pokemon with her fiance. She's excited about the prospect of losing weight before her wedding next year — and doing it while having fun.

“It's nice to be able to not just stare at a screen,” said Verger, 26, of Towson. “I feel more energized from moving around more and not just sitting and watching a show all the time. I have more energy to get up in the morning and go in early to work, and go for a walk before work.”

Though it's not clear how long Pokemon Go will be able to hold players' interest, Verger said she didn't anticipate stopping any time soon.

“I know that they're supposed to put out the second generation in December,” she said. “The game really can't end because they can add more to it.”

Bruce Y. Lee, director of the Global Obesity Prevention Center at the Bloomberg school and one of the authors of the Pokemon editorial, cautioned against seeing Pokemon Go as a primary means of weight management.

“It's absolutely not the solution to childhood obesity,” he said. “Physical activity is one part of the obesity epidemic, but it's one part.”

Often when a new exercise program comes out, people will lose weight — until they lose interest and regain the weight.

“Some new fad exercises or diets may seem to have an impact in the beginning, but then what happens is everyone adapts and you start creeping back to a new norm,” Lee said.

Yair Brito of Pikesville said he already works out but detests cardio activity. Once he got Pokemon Go, he started running miles for fun around Centennial Park near his job in Howard County so that he could hatch virtual eggs in the game. Some eggs require users to walk or run 10 kilometers, or about six miles, to hatch the egg.

Before the game, “I would say, ‘You're crazy, I'm not going to run six miles,'?” said Brito, 18. “It's like tricking people into working out.”

Aaron T. Barnes of Baltimore wears a fitness tracker and said he's gone from averaging 8,000 steps a day to averaging 14,000 since he started playing. It's more fun than going to the gym or trying to be more active for its own sake, he said.

Barnes, 31, a staff counselor at the counseling center at Loyola University Maryland, said he thinks the game-related exercise could help some students with mental health issues.

“We know that physical activity can reduce some of those symptoms of depression and anxiety,” he said. “For students who are more self-conscious about working out or going to the gym, being able to play a game is really accessible.”

Barnes said before he started playing, he had “these abstract goals of ‘I want to get fit or I want to walk more.'?” Those goals are “more concrete” now, he said.

“I want to catch a Growlithe,” a type of Pokemon, he said. “I want to catch Pikachu.”

cwells@baltsun.com