Rich Bell made headlines when he started playing Pokemon Go. In a single month, the 29-year-old lost more than 4kg chasing Zubats and Spearows.
In the weeks since, however, Bell has stopped playing - like many other early Pokemaniacs. He hasn't been walking as much; in fact, he thinks he may have gained some of his weight back.
Bell is not alone: A new report from researchers at Microsoft found that Pokemon Go initially contributed to a major uptick in physical activity among its players, with possibly staggering public health effects. After downloading the game, the average highly engaged player increased his daily walks by 1473 steps.
But one month after starting, the report found, those gains began to fade. Healthy or not, most players just get sick of the game.
"I went hard for a couple of months or so, but it got boring after a while," Bell said. "I've caught almost every Pokemon that I can, visited most nearby places that were good for playing - it just started getting repetitive."
To reach their conclusions, the researchers combed through owners of the Microsoft Band, Microsoft's wearable fitness tracker, looking for people who had opted into this sort of data collection and recently searched Bing for terms related to Pokemon Go. From there, the researchers were able to compare the physical activity of 1420 Microsoft Band users who played Pokemon with 50,000 who did not.
They observed a substantial increase in physical activity among players: on average, an extra 192 steps per day for each of the 30 days after they started playing. "Highly engaged" players, those who searched Bing for Pokemon Go terms repeatedly, increased their walks by even more steps: up to 1473 extra steps daily.
Those gains were particularly pronounced among young and sedentary people, or those who walk less than 5000 steps. After beginning the game, 32 per cent of frequent players met the recommended average activity guideline of 8000 daily steps - compared with 12.2 per cent before they started playing.
"Most surprising were the magnitude of the gains in physical activity and the significant benefits for low-activity populations," said Ryen White, chief technology officer for health intelligence at Microsoft and a co-author of the study. "Novel mobile games like Pokemon Go have important public health implications, especially as a complement to existing physical activity interventions."
Unfortunately, there's a caveat, White and his co-authors explain. Pokemon Go "would have the potential to measurably affect US life expectancy", they write - if high engagement could be sustained.
That could be changed, White argues: It's just a matter of design. New sorts of challenges, and new variants in the game, could keep people playing - and walking - for longer periods.
Bell says that could lure him back: He's looking forward to the release of Pokemon Go: Generation 2. "That'll probably get me back into it," he said. "At least for another month or two."