that dude might be fat but i'll gaurantee you his arms are bigger than 17 inches, i'd bet his forearms alone are close to 16.
another thing is : who cares.
maybe this guy plays football or is a powerlifter and could care less about how he looks.
the only person who cares is TA.
while he's wearing the tighest black shirt he can find (size medium) at the local bar, flexing his arms everytime he raises his drink, people will be laughing at him saying "can you belive that guy thinks he's big", while everyone stares and gets out of the way for the bigger guys like the guy from the above pic.