To further add to the thread, gaming has never strictly been for 'nerds'. Was always people who simply assumed that where a lot of people simply played games but didnt go around broadcasting themselves as gamers. So many terms came to light over the years in regards to peoples playing habits (hardcore gamers, casual gamers etc) so more people added themselves to groups.
Plus the fact that the industry makes so much money & appeals to such a large range of age groups these days that people had to stand up & take notice. Gaming has ended up going mainstream in the last 10 years & is more widely accepted as merely another hobby rather than being stereotyped as hobby for fat nerds as you so nicely put it. Playing games is simply becoming the same as watching a movie or liking a particular band these days.
Ive been gaming since I was about 5 but never been called a nerd (besides in jest) & I help run gaming sites & spend most of my time gaming or on gaming websites & I have done so from the age of 16 & im 26 now. Im not 300 pound, a nerd or a recluse, in fact I actually work for a Sports company & used to be a Boxer in my early teens & spent all my time outdoors or training. Not in a basement in the dark thats for sure, I spent more time outdoors than I did in the house. Yet ive always been a gamer since I can remember however & proud of it. I mean whos more shallow, the people who play games because they enjoy them or people who like things simply because they are popular or they think someone in it is hot?
I think most people have accepted that in this day & age gamers arent real life versions of the characters in The Big Bang Theory.