It will definitely affect obesity rates because you gotta walk more and that too with this engaging game will surely help to burn calories. Apart from your usual gym exercises this will help to balance the diet and hungry. Because you may gotta hatch those eggs as the last egg that gave you a Bulbasaur 141 CP and Pokemon go will make you go out and hatch some more!
The yes, although not by a lot. For some, it will make a big difference, as motivation seems to be the largest factor in exercise. You may hate working out, and hate exercising. Jogging, going to a gym, as it’s all awful.
This app could be the same for a lot of people. If you are finding activities to keep in shape is getting tougher. Pokemon Go maybe one answer. When you start to play and spend an hour or two just hitting that loop, stopping to chat with others, battle gyms and catch pokemon. This will make a change
It’s a great reason to get out and move, so for some, it’ll be a great thing. As for decreasing it? Yes, but most likely only by a small amount. Unless Niantic can do something to keep the game fresh (and fix all the broken issues, like speed not being a factor, there only being like 8 pokemon worth using for battles, and the constant bugs) it’s going to die quickly.
On an another side,
Plenty of fat people already exercise. You can exercise regularly and NOT lose weight, or have the weight loss from it be temporary (this is common, in fact, and most people abandon exercise efforts after not losing the weight they expected to).